diff options
| author | Ralf Baechle <ralf@linux-mips.org> | 2000-01-21 22:34:01 +0000 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2000-01-21 22:34:01 +0000 |
| commit | 9e30c3705aed9fbec4c3304570e4d6e707856bcb (patch) | |
| tree | b19e6acb5a67af31a4e7742e05c2166dc3f1444c /Documentation/filesystems | |
| parent | 72919904796333a20c6a5d5c380091b42e407aa9 (diff) | |
Merge with Linux 2.3.22.
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/proc.txt | 2559 | ||||
| -rw-r--r-- | Documentation/filesystems/smbfs.txt | 46 |
2 files changed, 1450 insertions, 1155 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index d842f7ed6..a17c05b0f 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1,1379 +1,1714 @@ - ------------------------------------------------------------------------ - - T H E /proc F I L E S Y S T E M - ------------------------------------------------------------------------ -/proc/sys Terrehon Bowden <terrehon@wpi.com> January 27 1999 - Bodo Bauer <bb@ricochet.net> ------------------------------------------------------------------------ -Version 1.1 Kernel version 2.2 ------------------------------------------------------------------------ -Contents - -1 Introduction/Credits - -1.1 Legal Issues - -2 The /proc file system - -2.1 Process specific subdirectories -2.2 Kernel data -2.3 IDE devices in /proc/ide -2.4 Networking info in /proc/net -2.5 SCSI info -2.6 Parallel port info in /proc/parport -2.7 TTY info in /proc/tty - -3 Reading and modifying kernel parameters - -3.1 /proc/sys/debug and /proc/sys/proc -3.2 /proc/fs - File system data -3.3 /proc/fs/binfmt_misc - Miscellaneous binary formats -3.4 /proc/sys/kernel - General kernel parameters -3.5 /proc/sys/vm - The virtual memory subsystem -3.6 /proc/sys/dev - Device specific parameters -3.7 /proc/sys/sunrpc - Remote procedure calls -3.8 /proc/sys/net - Networking stuff -3.9 /proc/sys/net/ipv4 - IPV4 settings=20 -3.10 Appletalk -3.11 IPX - ------------------------------------------------------------------------ - -1 Introduction/Credits - -This documentation is part of a soon to be released book published by -IDG Books on the SuSE Linux distribution. As there is no complete -documentation for the /proc file system and we've used many freely -available sources to write this chapter, it seems only fair to give -the work back to the Linux community. This work is based on the -2.1.132 and 2.2.0-pre-kernel versions. I'm afraid it's still far from -complete, but we hope it will be useful. As far as we know, it is the -first 'all-in-one' document about the /proc file system. It is -focused on the Intel x86 hardware, so if you are looking for PPC, ARM, -SPARC, APX, etc., features, you probably won't find what you are -looking for. It also only covers IPv4 networking, not IPv6 nor other -protocols - sorry. - -We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov. We'd -also like to extend a special thank you to Andi Kleen for -documentation, which we relied on heavily to create this document, as -well as the additional information he provided. Thanks to everybody -else who contributed source or docs to the Linux kernel and helped -create a great piece of software... :) - -If you have any comments, corrections or additions, please don't -hesitate to contact Bodo Bauer at bb@ricochet.net. We'll be happy to -add them to this document. - -The latest version of this document is available online at -http://www.suse.com/~bb/Docs/proc.html in HTML, ASCII, and as -Postscript file. - -1.1 Legal Stuff - -We don't guarantee the correctness of this document, and if you come -to us complaining about how you screwed up your system because of -incorrect documentation, we won't feel responsible... - ------------------------------------------------------------------------ - -2 The /proc file system - -The proc file system acts as an interface to internal data structures -in the kernel. It can be used to obtain information about the system -and to change certain kernel parameters at runtime. It contains -(among other things) one subdirectory for each process running on the -system which is named after the process id (PID) of the process. The -link self points to the process reading the file system. - -2.1 Process specific subdirectories - -Each process subdirectory has the in table 1.1 listed entries. - - _________________________________________________ - cmdline Command line arguments - environ Values of environment variables - fd Directory, which contains all file descriptors - mem Memory held by this process - stat Process status - status Process status in human readable form - cwd Link to the current working directory - exe Link to the executable of this process - maps Memory maps - root Link to the root directory of this process - statm Process memory status information - _________________________________________________ - Table 1.1: Process specific entries in /proc - -For example, to get the status information of a process, all you have -to do is read the file /proc/PID/status: - -> cat /proc/self/status -Name: cat -State: R (running) -Pid: 5633 -PPid: 5609 -Uid: 501 501 501 501 -Gid: 100 100 100 100 -Groups: 100 16 -VmSize: 804 kB -VmLck: 0 kB -VmRSS: 344 kB -VmData: 68 kB -VmStk: 20 kB -VmExe: 12 kB -VmLib: 660 kB -SigPnd: 0000000000000000 -SigBlk: 0000000000000000 -SigIgn: 0000000000000000 -SigCgt: 0000000000000000 -CapInh: 00000000fffffeff -CapPrm: 0000000000000000 -CapEff: 0000000000000000 - -This shows you almost the same information as you would get if you -viewed it with the ps command. In fact, ps uses the proc file system -to obtain its information. - -The statm file contains more detailed information about the process -memory usage. It contains seven values with the following meanings: - -size total program size -resident size of in memory portions -shared number of the pages that are shared -trs number of pages that are 'code' -drs number of pages of data/stack -lrs number of pages of library -dt number of dirty pages - -The ratio text/data/library is approximate only by heuristics. - -2.2 Kernel data - -Similar to the process entries, these are files which give information -about the running kernel. The files used to obtain this information -are contained in /proc and are listed in table 1.2. Not all of these -will be present in your system. It depends on the kernel configuration -and the loaded modules, which files are there, and which are missing. - - ________________________________________________ - apm Advanced power management info - cmdline Kernel command line - cpuinfo Info about the CPU - devices Available devices (block and character) - dma Used DMS channels - filesystems Supported filesystems - interrupts Interrupt usage - ioports I/O port usage - kcore Kernel core image - kmsg Kernel messages - ksyms Kernel symbol table - loadavg Load average - locks Kernel locks - meminfo Memory info - misc Miscellaneous - modules List of loaded modules - mounts Mounted filesystems - partitions Table of partitions known to the system - rtc Real time clock - slabinfo Slab pool info - stat Overall statistics - swaps Swap space utilization - uptime System uptime - version Kernel version - ________________________________________________ - Table 1.2: Kernel info in /proc - -You can, for example, check which interrupts are currently in use and -what they are used for by looking in the file /proc/interrupts: - -> cat /proc/interrupts - CPU0 - 0: 8728810 XT-PIC timer - 1: 895 XT-PIC keyboard - 2: 0 XT-PIC cascade - 3: 531695 XT-PIC aha152x - 4: 2014133 XT-PIC serial - 5: 44401 XT-PIC pcnet_cs - 8: 2 XT-PIC rtc - 11: 8 XT-PIC i82365 - 12: 182918 XT-PIC PS/2 Mouse - 13: 1 XT-PIC fpu - 14: 1232265 XT-PIC ide0 - 15: 7 XT-PIC ide1 -NMI: 0 - -There three more important subdirectories in /proc: net, scsi and -sys. The general rule is that the contents, or even the existence of -these directories, depends on your kernel configuration. If SCSI is -not enabled, the directory scsi may not exist. The same is true with -the net, which is only there when networking support is present in the -running kernel. - -The slabinfo file gives information about memory usage on the slab -level. Linux uses slab pools for memory management above page level -in version 2.2. Commonly used objects have their own slab pool (like -network buffers, directory cache, etc.). - -2.3 IDE devices in /proc/ide - -This subdirectory contains information about all IDE devices that the -kernel is aware of. There is one subdirectory for each device -(i.e. hard disk) containing the following files: - - cache The cache - capacity Capacity of the medium - driver Driver and version - geometry Physical and logical geometry - identify Device identify block - media Media type - model Device identifier - settings Device setup - smart_thresholds IDE disk management thresholds - smart_values IDE disk management values - -2.4 Networking info in /proc/net - -This directory follows the usual pattern. Table 1.3 lists the files -and their meaning. - - ____________________________________________________ - arp Kernel ARP table - dev network devices with statistics - dev_mcast Lists the Layer2 multicast groups a - device is listening to (interface index, - label, number of references, number of - bound addresses). - dev_stat network device status - ip_fwchains Firewall chain linkage - ip_fwnames Firewall chains - ip_masq Directory containing the masquerading - tables. - ip_masquerade Major masquerading table - netstat Network statistics - raw Raw device statistics - route Kernel routing table - rpc Directory containing rpc info - rt_cache Routing cache - snmp SNMP data - sockstat Socket statistics - tcp TCP sockets - tr_rif Token ring RIF routing table - udp UDP sockets - unix UNIX domain sockets - wireless Wireless interface data (Wavelan etc) - igmp IP multicast addresses, which this host joined - psched Global packet scheduler parameters. - netlink List of PF_NETLINK sockets. - ip_mr_vifs List of multicast virtual interfaces. - ip_mr_cache List of multicast routing cache. - udp6 UDP sockets (IPv6) - tcp6 TCP sockets (IPv6) - raw6 Raw device statistics (IPv6) - igmp6 IP multicast addresses, which this host joineed (IPv6) - if_inet6 List of IPv6 interface addresses. - ipv6_route Kernel routing table for IPv6 - rt6_stats global IPv6 routing tables statistics. - sockstat6 Socket statistics (IPv6) - snmp6 Snmp data (IPv6) - ____________________________________________________ - Table 1.3: Network info in /proc/net - -You can use this information to see which network devices are -available in your system and how much traffic was routed over those -devices: - -> cat /proc/net/dev -Inter-|Receive |[... - face |bytes packets errs drop fifo frame compressed multicast|[... - lo: 908188 5596 0 0 0 0 0 0 [... - ppp0:15475140 20721 410 0 0 410 0 0 [... - eth0: 614530 7085 0 0 0 0 0 1 [... - -...] Transmit -...] bytes packets errs drop fifo colls carrier compressed -...] 908188 5596 0 0 0 0 0 0 -...] 1375103 17405 0 0 0 0 0 0 -...] 1703981 5535 0 0 0 3 0 0 - -2.5 SCSI info - -If you have a SCSI host adapter in your system, you'll find a -subdirectory named after the driver for this adapter in /proc/scsi. -You'll also see a list of all recognized SCSI devices in /proc/scsi: - ->cat /proc/scsi/scsi -Attached devices: -Host: scsi0 Channel: 00 Id: 00 Lun: 00 - Vendor: QUANTUM Model: XP34550W Rev: LXY4 - Type: Direct-Access ANSI SCSI revision: 02 -Host: scsi0 Channel: 00 Id: 01 Lun: 00 - Vendor: SEAGATE Model: ST34501W Rev: 0018 - Type: Direct-Access ANSI SCSI revision: 02 -Host: scsi0 Channel: 00 Id: 02 Lun: 00 - Vendor: SEAGATE Model: ST34501W Rev: 0017 - Type: Direct-Access ANSI SCSI revision: 02 -Host: scsi0 Channel: 00 Id: 04 Lun: 00 - Vendor: ARCHIVE Model: Python 04106-XXX Rev: 703b - Type: Sequential-Access ANSI SCSI revision: 02 - -The directory named after the driver has one file for each adapter -found in the system. These files contain information about -the controller, including the used IRQ and the IO address range: - ->cat /proc/scsi/ncr53c8xx/0 -General information: - Chip NCR53C875, device id 0xf, revision id 0x4 - IO port address 0xec00, IRQ number 11 - Synchronous period factor 12, max commands per lun 4 - -2.6 Parallel port info in /proc/parport - -The directory /proc/parport contains information about the parallel -ports of your system. It has one subdirectory for each port, named -after the port number (0,1,2,...). - -This directory contains four files: - - autoprobe Autoprobe results of this port - devices Connected device modules - hardware Hardware info (port type, io-port, DMA, IRQ, etc.) - irq Used interrupt, if any - -2.7 TTY info in /proc/tty - -Information about the available and the actually used tty's can be -found in /proc/tty. You'll find entries for drivers and line -disciplines in this directory, as shown in the table below: - - drivers List of drivers and their usage - ldiscs Registered line disciplines - driver/serial Usage statistic and status of single tty lines - -To see which tty's are currently in use, you can simply look into the -file /proc/tty/drivers: - ->cat /proc/tty/drivers -pty_slave /dev/pts 136 0-255 pty:slave -pty_master /dev/ptm 128 0-255 pty:master -pty_slave /dev/ttyp 3 0-255 pty:slave -pty_master /dev/pty 2 0-255 pty:master -serial /dev/cua 5 64-67 serial:callout -serial /dev/ttyS 4 64-67 serial -/dev/tty0 /dev/tty0 4 0 system:vtmaster -/dev/ptmx /dev/ptmx 5 2 system -/dev/console /dev/console 5 1 system:console -/dev/tty /dev/tty 5 0 system:/dev/tty -unknown /dev/tty 4 1-63 console - ------------------------------------------------------------------------ - -3 Reading and modifying kernel parameters - -A very interesting part of /proc is the directory /proc/sys. This not -only provides information, it also allows you to change parameters -within the kernel. Be very careful when trying this. You can optimize -your system, but you also can crash it. Never play around with kernel -parameters on a production system. Set up a development machine and -test to make sure that everything works the way you want it to. You -may have no alternative but to reboot the machine once an error has -been made. - -To change a value, simply echo the new value into the file. An example -is given below in the section on the file system data. You need to be -root to do this. You can create your own boot script to get this done -every time your system boots. - -The files in /proc/sys can be used to tune and monitor miscellaneous -and general things in the operation of the Linux kernel. Since some -of the files can inadvertently disrupt your system, it is advisable to -read both documentation and source before actually making -adjustments. In any case, be very careful when writing to any of these -files. The entries in /proc may change slightly between the 2.1.* and -the 2.2 kernel, so review the kernel documentation if there is any -doubt. You'll find the documentation in the directory -/usr/src/linux/Documentation/sys. This chapter is heavily based on the -documentation included in the pre 2.2 kernels. Thanks to Rick van Riel -for providing this information. - -3.1 /proc/sys/debug and /proc/sys/proc - -These two subdirectories are empty. - -3.2 /proc/fs - File system data - -This subdirectory contains specific file system, file handle, inode, -dentry and quota information. +------------------------------------------------------------------------------ + T H E /proc F I L E S Y S T E M +------------------------------------------------------------------------------ +/proc/sys Terrehon Bowden <terrehon@pacbell.net> October 7 1999 + Bodo Bauer <bb@ricochet.net> +------------------------------------------------------------------------------ +Version 1.2 Kernel version 2.2.12 +------------------------------------------------------------------------------ + +Table of Contents +----------------- + + 0 Preface + 0.1 Introduction/Credits + 0.2 Legal Stuff + + 1 Collecting System Information + 1.1 Process-Specific Subdirectories + 1.2 Kernel data + 1.3 IDE devices in /proc/ide + 1.4 Networking info in /proc/net + 1.5 SCSI info + 1.6 Parallel port info in /proc/parport + 1.7 TTY info in /proc/tty + + 2 Modifying System Parameters + 2.1 /proc/sys/fs - File system data + 2.2 /proc/sys/fs/binfmt_misc - Miscellaneous binary formats + 2.3 /proc/sys/kernel - general kernel parameters + 2.4 /proc/sys/vm - The virtual memory subsystem + 2.5 /proc/sys/dev - Device specific parameters + 2.6 /proc/sys/sunrpc - Remote procedure calls + 2.7 /proc/sys/net - Networking stuff + 2.8 /proc/sys/net/ipv4 - IPV4 settings + 2.9 Appletalk + 2.10 IPX + +------------------------------------------------------------------------------ +Preface +------------------------------------------------------------------------------ + +0.1 Introduction/Credits +------------------------ + +This documentation is part of a soon (or so we hope) to be released book on +the SuSE Linux distribution. As there is no complete documentation for the +/proc file system and we've used many freely available sources to write these +chapters, it seems only fair to give the work back to the Linux community. +This work is based on the 2.2.* kernel version. I'm afraid it's still far from +complete, but we hope it will be useful. As far as we know, it is the first +'all-in-one' document about the /proc file system. It is focused on the Intel +x86 hardware, so if you are looking for PPC, ARM, SPARC, APX, etc., features, +you probably won't find what you are looking for. It also only covers IPv4 +networking, not IPv6 nor other protocols - sorry. But additions and patches +are welcome and will be added to this document if you mail them to Bodo. + +We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of +other people for help compiling this documentation. We'd also like to extend a +special thank you to Andi Kleen for documentation, which we relied on heavily +to create this document, as well as the additional information he provided. +Thanks to everybody else who contributed source or docs to the Linux kernel +and helped create a great piece of software... :) + +If you have any comments, corrections or additions, please don't hesitate to +contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this +document. + +The latest version of this document is available online at +http://skaro.nightcrawler.com/~bb/Docs/Proc as HTML version. + +0.2 Legal Stuff +--------------- + +We don't guarantee the correctness of this document, and if you come to us +complaining about how you screwed up your system because of incorrect +documentation, we won't feel responsible... + +------------------------------------------------------------------------------ +CHAPTER 1: COLLECTING SYSTEM INFORMATION +------------------------------------------------------------------------------ + +------------------------------------------------------------------------------ +In This Chapter +------------------------------------------------------------------------------ +* Investigating the properties of the pseudo file system /proc and its + ability to provide information on the running Linux system +* Examining /proc's structure +* Uncovering various information about the kernel and the processes running + on the system +------------------------------------------------------------------------------ + + +The proc file system acts as an interface to internal data structures in the +kernel. It can be used to obtain information about the system and to change +certain kernel parameters at runtime. + +First, we'll take a look at the read-only parts of /proc. In Chapter 2, we +show you how you can use /proc/sys to change settings. + +1.1 Process-Specific Subdirectories +----------------------------------- + +The directory /proc contains (among other things) one subdirectory for each +process running on the system, which is named after the process ID (PID). + +The link self points to the process reading the file system. Each process +subdirectory has the entries listed in Table 1-1. + + +Table 1-1: Process specific entries in /proc +.............................................................................. + File Content + cmdline Command line arguments + environ Values of environment variables + fd Directory, which contains all file descriptors + mem Memory held by this process + stat Process status + status Process status in human readable form + cwd Link to the current working directory + exe Link to the executable of this process + maps Memory maps + root Link to the root directory of this process + statm Process memory status information +.............................................................................. + +For example, to get the status information of a process, all you have to do is +read the file /proc/PID/status: + + >cat /proc/self/status + Name: cat + State: R (running) + Pid: 5452 + PPid: 743 + Uid: 501 501 501 501 + Gid: 100 100 100 100 + Groups: 100 14 16 + VmSize: 1112 kB + VmLck: 0 kB + VmRSS: 348 kB + VmData: 24 kB + VmStk: 12 kB + VmExe: 8 kB + VmLib: 1044 kB + SigPnd: 0000000000000000 + SigBlk: 0000000000000000 + SigIgn: 0000000000000000 + SigCgt: 0000000000000000 + CapInh: 00000000fffffeff + CapPrm: 0000000000000000 + CapEff: 0000000000000000 + + +This shows you nearly the same information you would get if you viewed it with +the ps command. In fact, ps uses the proc file system to obtain its +information. The statm file contains more detailed information about the +process memory usage. Its seven fields are explained in Table 1-2. + + +Table 1-2: Contents of the statm files +.............................................................................. + File Content + size total program size + resident size of memory portions + shared number of pages that are shared + trs number of pages that are 'code' + drs number of pages of data/stack + lrs number of pages of library + dt number of dirty pages +.............................................................................. + +1.2 Kernel data +--------------- + +Similar to the process entries, the kernel data files give information about +the running kernel. The files used to obtain this information are contained in +/proc and are listed in Table 1-3. Not all of these will be present in your +system. It depends on the kernel configuration and the loaded modules, which +files are there, and which are missing. + +Table 1-3: Kernel info in /proc +.............................................................................. + File Content + apm Advanced power management info + bus Directory containing bus specific information + cmdline Kernel command line + cpuinfo Info about the CPU + devices Available devices (block and character) + dma Used DMS channels + filesystems Supported filesystems + ide Directory containing info about the IDE subsystem + interrupts Interrupt usage + ioports I/O port usage + kcore Kernel core image + kmsg Kernel messages + ksyms Kernel symbol table + loadavg Load average + locks Kernel locks + meminfo Memory info + misc Miscellaneous + modules List of loaded modules + mounts Mounted filesystems + net Networking info (see text) + partitions Table of partitions known to the system + rtc Real time clock + scsi SCSI info (see text) + slabinfo Slab pool info + stat Overall statistics + swaps Swap space utilization + sys See chapter 2 + uptime System uptime + version Kernel version +.............................................................................. + +You can, for example, check which interrupts are currently in use and what +they are used for by looking in the file /proc/interrupts: + + > cat /proc/interrupts + CPU0 + 0: 8728810 XT-PIC timer + 1: 895 XT-PIC keyboard + 2: 0 XT-PIC cascade + 3: 531695 XT-PIC aha152x + 4: 2014133 XT-PIC serial + 5: 44401 XT-PIC pcnet_cs + 8: 2 XT-PIC rtc + 11: 8 XT-PIC i82365 + 12: 182918 XT-PIC PS/2 Mouse + 13: 1 XT-PIC fpu + 14: 1232265 XT-PIC ide0 + 15: 7 XT-PIC ide1 + NMI: 0 + + +There are three more important subdirectories in /proc: net, scsi, and sys. +The general rule is that the contents, or even the existence of these +directories, depend on your kernel configuration. If SCSI is not enabled, the +directory scsi may not exist. The same is true with the net, which is there +only when networking support is present in the running kernel. + +The slabinfo file gives information about memory usage at the slab level. +Linux uses slab pools for memory management above page level in version 2.2. +Commonly used objects have their own slab pool (such as network buffers, +directory cache, and so on). + +1.3 IDE devices in /proc/ide +---------------------------- + +The subdirectory /proc/ide contains information about all IDE devices of which +the kernel is aware. There is one subdirectory for each IDE controller, the +file drivers and a link for each IDE device, pointing to the device directory +in the controller specific subtree. + +The file drivers contains general information about the drivers used for the +IDE devices: + + > cat /proc/ide/drivers + ide-cdrom version 4.53 + ide-disk version 1.08 + + +More detailed information can be found in the controller specific +subdirectories. These are named ide0, ide1 and so on. Each of these +directories contains the files shown in table 1-4. + + +Table 1-4: IDE controller info in /proc/ide/ide? +.............................................................................. + File Content + channel IDE channel (0 or 1) + config Configuration (only for PCI/IDE bridge) + mate Mate name + model Type/Chipset of IDE controller +.............................................................................. + +Each device connected to a controller has a separate subdirectory in the +controllers directory. The files listed in table 1-5 are contained in these +directories. + + +Table 1-5: IDE device information +.............................................................................. + File Content + cache The cache + capacity Capacity of the medium (in 512Byte blocks) + driver driver and version + geometry physical and logical geometry + identify device identify block + media media type + model device identifier + settings device setup + smart_thresholds IDE disk management thresholds + smart_values IDE disk management values +.............................................................................. + +The most interesting file is settings. This file contains a nice overview of +the drive parameters: + + # cat /proc/ide/ide0/hda/settings + name value min max mode + ---- ----- --- --- ---- + bios_cyl 526 0 65535 rw + bios_head 255 0 255 rw + bios_sect 63 0 63 rw + breada_readahead 4 0 127 rw + bswap 0 0 1 r + file_readahead 72 0 2097151 rw + io_32bit 0 0 3 rw + keepsettings 0 0 1 rw + max_kb_per_request 122 1 127 rw + multcount 0 0 8 rw + nice1 1 0 1 rw + nowerr 0 0 1 rw + pio_mode write-only 0 255 w + slow 0 0 1 rw + unmaskirq 0 0 1 rw + using_dma 0 0 1 rw + + +1.4 Networking info in /proc/net +-------------------------------- + +The subdirectory /proc/net follows the usual pattern. Table 1-6 shows the +additional values you get for IP version 6 if you configure the kernel to +support this. Table 1-7 lists the files and their meaning. + + +Table 1-6: IPv6 info in /proc/net +.............................................................................. + File Content + udp6 UDP sockets (IPv6) + tcp6 TCP sockets (IPv6) + raw6 Raw device statistics (IPv6) + igmp6 IP multicast addresses, which this host joined (IPv6) + if_inet6 List of IPv6 interface addresses + ipv6_route Kernel routing table for IPv6 + rt6_stats Global IPv6 routing tables statistics + sockstat6 Socket statistics (IPv6) + snmp6 Snmp data (IPv6) +.............................................................................. + + +Table 1-7: Network info in /proc/net +.............................................................................. + File Content + arp Kernel ARP table + dev network devices with statistics + dev_mcast the Layer2 multicast groups a device is listening too + (interface index, label, number of references, number of bound + addresses). + dev_stat network device status + ip_fwchains Firewall chain linkage + ip_fwnames Firewall chain names + ip_masq Directory containing the masquerading tables + ip_masquerade Major masquerading table + netstat Network statistics + raw raw device statistics + route Kernel routing table + rpc Directory containing rpc info + rt_cache Routing cache + snmp SNMP data + sockstat Socket statistics + tcp TCP sockets + tr_rif Token ring RIF routing table + udp UDP sockets + unix UNIX domain sockets + wireless Wireless interface data (Wavelan etc) + igmp IP multicast addresses, which this host joined + psched Global packet scheduler parameters. + netlink List of PF_NETLINK sockets + ip_mr_vifs List of multicast virtual interfaces + ip_mr_cache List of multicast routing cache +.............................................................................. + +You can use this information to see which network devices are available in +your system and how much traffic was routed over those devices: + + > cat /proc/net/dev + Inter-|Receive |[... + face |bytes packets errs drop fifo frame compressed multicast|[... + lo: 908188 5596 0 0 0 0 0 0 [... + ppp0:15475140 20721 410 0 0 410 0 0 [... + eth0: 614530 7085 0 0 0 0 0 1 [... + + ...] Transmit + ...] bytes packets errs drop fifo colls carrier compressed + ...] 908188 5596 0 0 0 0 0 0 + ...] 1375103 17405 0 0 0 0 0 0 + ...] 1703981 5535 0 0 0 3 0 0 + + +1.5 SCSI info +------------- + +If you have a SCSI host adapter in your system, you'll find a subdirectory +named after the driver for this adapter in /proc/scsi. You'll also see a list +of all recognized SCSI devices in /proc/scsi: + + >cat /proc/scsi/scsi + Attached devices: + Host: scsi0 Channel: 00 Id: 00 Lun: 00 + Vendor: IBM Model: DGHS09U Rev: 03E0 + Type: Direct-Access ANSI SCSI revision: 03 + Host: scsi0 Channel: 00 Id: 06 Lun: 00 + Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04 + Type: CD-ROM ANSI SCSI revision: 02 + + +The directory named after the driver has one file for each adapter found in +the system. These files contain information about the controller, including +the used IRQ and the IO address range. The amount of information shown is +dependent on the adapter you use. The example shows the output for an Adaptec +AHA-2940 SCSI adapter: + + > cat /proc/scsi/aic7xxx/0 + + Adaptec AIC7xxx driver version: 5.1.19/3.2.4 + Compile Options: + TCQ Enabled By Default : Disabled + AIC7XXX_PROC_STATS : Disabled + AIC7XXX_RESET_DELAY : 5 + Adapter Configuration: + SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter + Ultra Wide Controller + PCI MMAPed I/O Base: 0xeb001000 + Adapter SEEPROM Config: SEEPROM found and used. + Adaptec SCSI BIOS: Enabled + IRQ: 10 + SCBs: Active 0, Max Active 2, + Allocated 15, HW 16, Page 255 + Interrupts: 160328 + BIOS Control Word: 0x18b6 + Adapter Control Word: 0x005b + Extended Translation: Enabled + Disconnect Enable Flags: 0xffff + Ultra Enable Flags: 0x0001 + Tag Queue Enable Flags: 0x0000 + Ordered Queue Tag Flags: 0x0000 + Default Tag Queue Depth: 8 + Tagged Queue By Device array for aic7xxx host instance 0: + {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255} + Actual queue depth per device for aic7xxx host instance 0: + {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1} + Statistics: + (scsi0:0:0:0) + Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8 + Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0) + Total transfers 160151 (74577 reads and 85574 writes) + (scsi0:0:6:0) + Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15 + Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0) + Total transfers 0 (0 reads and 0 writes) + + +1.6 Parallel port info in /proc/parport +--------------------------------------- + +The directory /proc/parport contains information about the parallel ports of +your system. It has one subdirectory for each port, named after the port +number (0,1,2,...). + +These directories contain the four files shown in Table 1-8. + + +Table 1-8: Files in /proc/parport +.............................................................................. + File Content + autoprobe Any IEEE-1284 device ID information that has been acquired. + devices list of the device drivers using that port. A + will appear by the + name of the device currently using the port (it might not appear + against any). + hardware Parallel port's base address, IRQ line and DMA channel. + irq IRQ that parport is using for that port. This is in a separate + file to allow you to alter it by writing a new value in (IRQ + number or none). +.............................................................................. + +1.7 TTY info in /proc/tty +------------------------- + +Information about the available and actually used tty's can be found in the +directory /proc/tty.You'll find entries for drivers and line disciplines in +this directory, as shown in Table 1-9. + + +Table 1-9: Files in /proc/tty +.............................................................................. + File Content + drivers list of drivers and their usage + ldiscs registered line disciplines + driver/serial usage statistic and status of single tty lines +.............................................................................. + +To see which tty's are currently in use, you can simply look into the file +/proc/tty/drivers: + + > cat /proc/tty/drivers + pty_slave /dev/pts 136 0-255 pty:slave + pty_master /dev/ptm 128 0-255 pty:master + pty_slave /dev/ttyp 3 0-255 pty:slave + pty_master /dev/pty 2 0-255 pty:master + serial /dev/cua 5 64-67 serial:callout + serial /dev/ttyS 4 64-67 serial + /dev/tty0 /dev/tty0 4 0 system:vtmaster + /dev/ptmx /dev/ptmx 5 2 system + /dev/console /dev/console 5 1 system:console + /dev/tty /dev/tty 5 0 system:/dev/tty + unknown /dev/tty 4 1-63 console + + +------------------------------------------------------------------------------ +Summary +------------------------------------------------------------------------------ +The /proc file system serves information about the running system. It not only +allows access to process data but also allows you to request the kernel status +by reading files in the hierarchy. + +The directory structure of /proc reflects the types of information and makes +it easy, if not obvious, where to look for specific data. +------------------------------------------------------------------------------ + +------------------------------------------------------------------------------ +CHAPTER 2: MODIFYING SYSTEM PARAMETERS +------------------------------------------------------------------------------ + +------------------------------------------------------------------------------ +In This Chapter +------------------------------------------------------------------------------ +* Modifying kernel parameters by writing into files found in /proc/sys +* Exploring the files which modify certain parameters +* Review of the /proc/sys file tree +------------------------------------------------------------------------------ + + +A very interesting part of /proc is the directory /proc/sys. This is not only +a source of information, it also allows you to change parameters within the +kernel. Be very careful when attempting this. You can optimize your system, +but you can also cause it to crash. Never alter kernel parameters on a +production system. Set up a development machine and test to make sure that +everything works the way you want it to. You may have no alternative but to +reboot the machine once an error has been made. + +To change a value, simply echo the new value into the file. An example is +given below in the section on the file system data. You need to be root to do +this. You can create your own boot script to perform this every time your +system boots. + +The files in /proc/sys can be used to fine tune and monitor miscellaneous and +general things in the operation of the Linux kernel. Since some of the files +can inadvertently disrupt your system, it is advisable to read both +documentation and source before actually making adjustments. In any case, be +very careful when writing to any of these files. The entries in /proc may +change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt +review the kernel documentation in the directory /usr/src/linux/Documentation. +This chapter is heavily based on the documentation included in the pre 2.2 +kernels, and became part of it in version 2.2.1 of the Linux kernel. + +2.1 /proc/sys/fs - File system data +----------------------------------- + +This subdirectory contains specific file system, file handle, inode, dentry +and quota information. Currently, these files are in /proc/sys/fs: dentry-state - Status of the directory cache. Since directory entries are - dynamically allocated and deallocated, this file gives information - about the current status. It holds six values, in which the last - two are not used and are always zero. The other four mean: +------------ + +Status of the directory cache. Since directory entries are dynamically +allocated and deallocated, this file indicates the current status. It holds +six values, in which the last two are not used and are always zero. The others +are listed in table 2-1. + - nr_dentry Seems to be zero all the time - nr_unused Number of unused cache entries - age_limit Age in seconds after the entry may be - reclaimed, when memory is short - want_pages internal +Table 2-1: Status files of the directory cache +.............................................................................. + File Content + nr_dentry Almost always zero + nr_unused Number of unused cache entries + age_limit + in seconds after the entry may be reclaimed, when memory is short + want_pages internally +.............................................................................. dquot-nr and dquot-max - The file dquot-max shows the maximum number of cached disk quota - entries. +---------------------- - The file dquot-nr shows the number of allocated disk quota - entries and the number of free disk quota entries. +The file dquot-max shows the maximum number of cached disk quota entries. - If the number of free cached disk quotas is very low and you have - a large number of simultaneous system users, you might want - to raise the limit. +The file dquot-nr shows the number of allocated disk quota entries and the +number of free disk quota entries. + +If the number of available cached disk quotas is very low and you have a large +number of simultaneous system users, you might want to raise the limit. file-nr and file-max - The kernel allocates file handles dynamically, but as yet - doesn't free them again. - - The value in file-max denotes the maximum number of file handles - that the Linux kernel will allocate. When you get a lot of error - messages about running out of file handles, you might want to raise - this limit. The default value is 4096. To change it, just write the - new number into the file: - - # cat /proc/sys/fs/file-max - 4096 - # echo 8192 > /proc/sys/fs/file-max - # cat /proc/sys/fs/file-max - 8192 - - This method of revision is useful for all customizable parameters - of the kernel - simply echo the new value to the corresponding - file. - - The three values in file-nr denote the number of allocated file - handles, the number of used file handles, and the maximum number of - file handles. When the allocated file handles come close to the - maximum, but the number of actually used ones is far behind, you've - encountered a peak in your usage of file handles and you don't need - to increase the maximum. - - However, there is still a per process limit of open files, which - unfortunatly can't be changed that easily. It is set to 1024 by - default. To change this you have to edit the files limits.h and - fs.h in the directory /usr/src/linux/include/linux. Change the - definition of NR_OPEN and recompile the kernel. +-------------------- + +The kernel allocates file handles dynamically, but doesn't free them again at +this time. + +The value in file-max denotes the maximum number of file handles that the +Linux kernel will allocate. When you get a lot of error messages about running +out of file handles, you might want to raise this limit. The default value is +4096. To change it, just write the new number into the file: + + # cat /proc/sys/fs/file-max + 4096 + # echo 8192 > /proc/sys/fs/file-max + # cat /proc/sys/fs/file-max + 8192 + + +This method of revision is useful for all customizable parameters of the +kernel - simply echo the new value to the corresponding file. + +The three values in file-nr denote the number of allocated file handles, the +number of used file handles, and the maximum number of file handles. When the +allocated file handles come close to the maximum, but the number of actually +used ones is far behind, you've encountered a peak in your usage of file +handles and you don't need to increase the maximum. + +However, there is still a per process limit of open files, which unfortunately +can't be changed that easily. It is set to 1024 by default. To change this you +have to edit the files limits.h and fs.h in the kernel source tree. Finally, +change the definition of NR_OPEN and recompile the kernel. inode-state, inode-nr and inode-max - As with file handles, the kernel allocates the inode structures - dynamically, but can't free them yet. +----------------------------------- + +As with file handles, the kernel allocates the inode structures dynamically, +but can't free them yet. + +The value in inode-max denotes the maximum number of inode handlers. This +value should be 3 to 4 times larger than the value in file-max, since stdin, +stdout, and network sockets also need an inode struct to handle them. If you +regularly run out of inodes, you should increase this value. - The value in inode-max denotes the maximum number of inode - handlers. This value should be 3 to 4 times larger than the value - in file-max, since stdin, stdout, and network sockets also need an - inode struct to handle them. If you regularly run out of inodes, - you should increase this value. +The file inode-nr contains the first two items from inode-state, so we'll skip +to that file... - The file inode-nr contains the first two items from inode-state, so - we'll skip to that file... +inode-state contains three actual numbers and four dummy values. The numbers +are nr_inodes, nr_free_inodes, and preshrink (in order of appearance). - inode-state contains three actual numbers and four dummy values. The - actual numbers are (in order of appearance) nr_inodes, nr_free_inodes, - and preshrink. +nr_inodes +~~~~~~~~~ - nr_inodes - Denotes the number of inodes the system has allocated. This can - be slightly more than inode-max because Linux allocates them one - pageful at a time. +Denotes the number of inodes the system has allocated. This can be slightly +more than inode-max because Linux allocates them one pageful at a time. + +nr_free_inodes +-------------- + +Represents the number of free inodes and preshrink is nonzero when nr_inodes +is greater than inode-max and the system needs to prune the inode list instead +of allocating more. - nr_free_inodes - Represents the number of free inodes and pre shrink is nonzero - when the nr_inodes > inode-max and the system needs to prune the - inode list instead of allocating more. super-nr and super-max - Again, super block structures are allocated by the kernel, - but not freed. The file super-max contains the maximum number of - super block handlers, where super-nr shows the number of - currently allocated ones. +---------------------- - Every mounted file system needs a super block, so if you plan to - mount lots of file systems, you may want to increase these - numbers. +Again, super block structures are allocated by the kernel, but not freed. The +file super-max contains the maximum number of super block handlers, where +super-nr shows the number of currently allocated ones. -3.3 /proc/fs/binfmt_misc - Miscellaneous binary formats +Every mounted file system needs a super block, so if you plan to mount lots of +file systems, you may want to increase these numbers. -Besides these files, there is the subdirectory -/proc/sys/fs/binfmt_misc. This handles the kernel support for -miscellaneous binary formats. +2.2 /proc/sys/fs/binfmt_misc - Miscellaneous binary formats +----------------------------------------------------------- -Binfmt_misc provides the ability to register additional binary formats -to the Kernel without compiling an additional module/kernel. Therefore -binfmt_misc needs to know magic numbers at the beginning or the -filename extension of the binary. +Besides these files, there is the subdirectory /proc/sys/fs/binfmt_misc. This +handles the kernel support for miscellaneous binary formats. -It works by maintaining a linked list of structs, that contain a -description of a binary format, including a magic with size (or the -filename extension), offset and mask, and the interpreter name. On -request it invokes the given interpreter with the original program as -argument, as binfmt_java and binfmt_em86 and binfmt_mz do. -Since binfmt_misc does not define any default binary-formats, you have to -register an additional binary-format. +Binfmt_misc provides the ability to register additional binary formats to the +Kernel without compiling an additional module/kernel. Therefore, binfmt_misc +needs to know magic numbers at the beginning or the filename extension of the +binary. -There are two general files in binfmt_misc and one file per registered -format. The two general files are register and status. +It works by maintaining a linked list of structs that contain a description of +a binary format, including a magic with size (or the filename extension), +offset and mask, and the interpreter name. On request it invokes the given +interpreter with the original program as argument, as binfmt_java and +binfmt_em86 and binfmt_mz do. Since binfmt_misc does not define any default +binary-formats, you have to register an additional binary-format. + +There are two general files in binfmt_misc and one file per registered format. +The two general files are register and status. Registering a new binary format +------------------------------- + +To register a new binary format you have to issue the command -echo :name:type:offset:magic:mask:interpreter: > /proc/sys/fs/binfmt_misc/register + echo :name:type:offset:magic:mask:interpreter: > /proc/sys/fs/binfmt_misc/register -with appropriate name (the name for the /proc-dir entry), offset -(defaults to 0, if omitted), magic and mask (which can be omitted, -defaults to all 0xff) and last but not least, the interpreter that is -to be invoked (for example and testing '/bin/echo'). Type can be M for -usual magic matching or E for filename extension matching (give -extension in place of magic). -To check or reset the status of the binary format handler: -If you do a cat on the file /proc/sys/fs/binfmt_misc/status, you will -get the current status (enabled/disabled) of binfmt_misc. Change the -status by echoing 0 (disables) or 1 (enables) or -1 (caution: this -clears all previously registered binary formats) to status. For -example echo 0 > status to disable binfmt_misc (temporarily). +with appropriate name (the name for the /proc-dir entry), offset (defaults to +0, if omitted), magic, mask (which can be omitted, defaults to all 0xff) and +last but not least, the interpreter that is to be invoked (for example and +testing /bin/echo). Type can be M for usual magic matching or E for filename +extension matching (give extension in place of magic). + +Check or reset the status of the binary format handler +------------------------------------------------------ + +If you do a cat on the file /proc/sys/fs/binfmt_misc/status, you will get the +current status (enabled/disabled) of binfmt_misc. Change the status by echoing +0 (disables) or 1 (enables) or -1 (caution: this clears all previously +registered binary formats) to status. For example echo 0 > status to disable +binfmt_misc (temporarily). Status of a single handler +-------------------------- -Each registered handler has an entry in /proc/sys/fs/binfmt_misc. -These files perform the same function as status, but their scope is -limited to the actual binary format. By cating this file, you also -receive all related information about the interpreter/magic of the -binfmt. +Each registered handler has an entry in /proc/sys/fs/binfmt_misc. These files +perform the same function as status, but their scope is limited to the actual +binary format. By cating this file, you also receive all related information +about the interpreter/magic of the binfmt. Example usage of binfmt_misc (emulate binfmt_java) +-------------------------------------------------- -cd /proc/sys/fs/binfmt_misc -echo ':Java:M::\xca\xfe\xba\xbe::/usr/local/java/bin/javawrapper:' > register -echo ':HTML:E::html::/usr/local/java/bin/appletviewer:' > register -echo ':Applet:M::<!--applet::/usr/local/java/bin/appletviewer:' > register -echo ':DEXE:M::\x0eDEX::/usr/bin/dosexec:' > register + cd /proc/sys/fs/binfmt_misc + echo ':Java:M::\xca\xfe\xba\xbe::/usr/local/java/bin/javawrapper:' > register + echo ':HTML:E::html::/usr/local/java/bin/appletviewer:' > register + echo ':Applet:M::<!--applet::/usr/local/java/bin/appletviewer:' > register + echo ':DEXE:M::\x0eDEX::/usr/bin/dosexec:' > register -These three lines add support for Java executables and Java applets -(like binfmt_java, additionally recognizing the .html extension with -no need to put <!--applet> to every applet file). You have to install -the JDK and the shell-script /usr/local/java/bin/javawrapper too. It -works around the brokenness of the Java filename handling. To add a -Java binary, just create a link to the class-file somewhere in the -path. -3.4 /proc/sys/kernel - general kernel parameters +These four lines add support for Java executables and Java applets (like +binfmt_java, additionally recognizing the .html extension with no need to put +<!--applet> to every applet file). You have to install the JDK and the +shell-script /usr/local/java/bin/javawrapper too. It works around the +brokenness of the Java filename handling. To add a Java binary, just create a +link to the class-file somewhere in the path. -This directory reflects general kernel behaviors. As I've said before, -the contents are depend on your configuration. I'll list the most -important files, along with descriptions of what they mean and how to -use them. +2.3 /proc/sys/kernel - general kernel parameters +------------------------------------------------ + +This directory reflects general kernel behaviors. As I've said before, the +contents depend on your configuration. Here you'll find the most important +files, along with descriptions of what they mean and how to use them. acct - The file contains three values; highwater, lowwater, and - frequency. - - It exists only when BSD-style process accounting is enabled. These - values control its behavior. If the free space on the file system - where the log lives goes below lowwater%, accounting suspends. If - it goes above highwater%, accounting resumes. Frequency determines - how often you check the amount of free space (value is in - seconds). Default settings are: 4, 2, and 30. That is, suspend - accounting if there left <= 2% free; resume it if we have a value - >=3%; consider information about the amount of free space valid - for 30 seconds +---- + +The file contains three values; highwater, lowwater, and frequency. + +It exists only when BSD-style process accounting is enabled. These values +control its behavior. If the free space on the file system where the log lives +goes below lowwater percentage, accounting suspends. If it goes above +highwater percentage, accounting resumes. Frequency determines how often you +check the amount of free space (value is in seconds). Default settings are: 4, +2, and 30. That is, suspend accounting if there is less than 2 percent free; +resume it if we have a value of 3 or more percent; consider information about +the amount of free space valid for 30 seconds ctrl-alt-del - When the value in this file is 0, ctrl-alt-del is trapped and sent - to the init(1) program to handle a graceful restart. However, when - the value is > 0, Linux's reaction to this key combination will be - an immediate reboot, without syncing its dirty buffers. +------------ + +When the value in this file is 0, ctrl-alt-del is trapped and sent to the init +program to handle a graceful restart. However, when the value is greater that +zero, Linux's reaction to this key combination will be an immediate reboot, +without syncing its dirty buffers. - Note: when a program (like dosemu) has the keyboard in raw mode, - the ctrl-alt-del is intercepted by the program before it ever - reaches the kernel tty layer, and it is up to the program to decide - what to do with it. +[NOTE] + When a program (like dosemu) has the keyboard in raw mode, the + ctrl-alt-del is intercepted by the program before it ever reaches the + kernel tty layer, and it is up to the program to decide what to do with + it. domainname and hostname - These files can be controlled to set the NIS domainname and - hostname of your box. For the classic darkstar.frop.org a simple: +----------------------- + +These files can be controlled to set the NIS domainname and hostname of your +box. For the classic darkstar.frop.org a simple: + + # echo "darkstar" > /proc/sys/kernel/hostname + # echo "frop.org" > /proc/sys/kernel/domainname - # echo "darkstar" > /proc/sys/kernel/hostname - # echo "frop.org" > /proc/sys/kernel/domainname - would suffice to set your hostname and NIS domainname. +would suffice to set your hostname and NIS domainname. osrelease, ostype and version +----------------------------- - The names make it pretty obvious what these fields contain: - - >cat /proc/sys/kernel/osrelease - 2.1.131 - >cat /proc/sys/kernel/ostype - Linux - >cat /proc/sys/kernel/version - #8 Mon Jan 25 19:45:02 PST 1999 - - The files osrelease and ostype should be clear enough. Version - needs a little more clarification however. The #8 means that this - is the 8th kernel built from this source base and the date behind - it indicates the time the kernel was built. The only way to tune - these values is to rebuild the kernel. - -panic - The value in this file represents the number of seconds the kernel - waits before rebooting on a panic. When you use the software - watchdog, the recommended setting is 60. If set to 0, the auto - reboot after a kernel panic is disabled, this is the default - setting. +The names make it pretty obvious what these fields contain: + + > cat /proc/sys/kernel/osrelease + 2.2.12 + + > cat /proc/sys/kernel/ostype + Linux + + > cat /proc/sys/kernel/version + #4 Fri Oct 1 12:41:14 PDT 1999 + + +The files osrelease and ostype should be clear enough. Version needs a little +more clarification. The #4 means that this is the 4th kernel built from this +source base and the date after it indicates the time the kernel was built. The +only way to tune these values is to rebuild the kernel. + +panic +----- + +The value in this file represents the number of seconds the kernel waits +before rebooting on a panic. When you use the software watchdog, the +recommended setting is 60. If set to 0, the auto reboot after a kernel panic +is disabled, which is the default setting. printk - The four values in printk denote console_loglevel, - default_message_loglevel, minimum_console_level, and - default_console_loglevel respectively. +------ + +The four values in printk denote +* console_loglevel, +* default_message_loglevel, +* minimum_console_level and +* default_console_loglevel +respectively. + +These values influence printk() behavior when printing or logging error +messages, which come from inside the kernel. See syslog(2) for more +information on the different log levels. + +console_loglevel +---------------- - These values influence printk() behavior when printing or logging - error messages, which come from inside the kernel. See syslog(2) - for more information on the different log levels. +Messages with a higher priority than this will be printed to the console. - console_loglevel - Messages with a higher priority than this will be printed to - the console. +default_message_level +--------------------- - default_message_level - Messages without an explicit priority will be printed with - this priority. +Messages without an explicit priority will be printed with this priority. - minimum_console_loglevel - Minimum (highest) value to which the console_loglevel can be set. +minimum_console_loglevel +------------------------ - default_console_loglevel - Default value for console_loglevel. +Minimum (highest) value to which the console_loglevel can be set. + +default_console_loglevel +------------------------ + +Default value for console_loglevel. sg-big-buff - This file shows the size of the generic SCSI (sg) buffer. At this - point, you can't tune it yet, but you can change it at compile time - by editing include/scsi/sg.h and changing the value of - SG_BIG_BUFF. +----------- - If you use a scanner with SANE (Scanner Access now easy) you - might want to set this to a higher value. Look into the SANE - documentation on this issue. +This file shows the size of the generic SCSI (sg) buffer. At this point, you +can't tune it yet, but you can change it at compile time by editing +include/scsi/sg.h and changing the value of SG_BIG_BUFF. + +If you use a scanner with SANE (Scanner Access Now Easy) you might want to set +this to a higher value. Refer to the SANE documentation on this issue. modprobe - The location where the modprobe binary is located. The kernel - uses this program to load modules on demand. +-------- + +The location where the modprobe binary is located. The kernel uses this +program to load modules on demand. -3.5 /proc/sys/vm - The virtual memory subsystem +2.4 /proc/sys/vm - The virtual memory subsystem +----------------------------------------------- -The files in this directory can be used to tune the operation of the -virtual memory (VM) subsystem of the Linux kernel. In addition, one of -the files (bdflush) has a little influence on disk usage. +The files in this directory can be used to tune the operation of the virtual +memory (VM) subsystem of the Linux kernel. In addition, one of the files +(bdflush) has some influence on disk usage. bdflush - This file controls the operation of the bdflush kernel daemon. It - currently contains 9 integer values, 6 of which are actually used - by the kernel: - - nfract Percentage of buffer cache dirty to - activate bdflush - ndirty Maximum number of dirty blocks to - write out per-wake-cycle - nrefill Number of clean buffers to try to obtain - each time we call refill - nref_dirt Dirty buffer threshold for activating bdflush - when trying to refill buffers. - dummy unused - age_buffer Time for normal buffer to age before you flush it - age_super Time for superblock to age before you flush it - dummy unused - dummy unused - - nfract - This parameter governs the maximum number of dirty buffers - in the buffer cache. Dirty means that the contents of the - buffer still have to be written to disk (as opposed to a - clean buffer, which can just be forgotten about). Setting - this to a high value means that Linux can delay disk writes - for a long time, but it also means that it will have to do a - lot of I/O at once when memory becomes short. A low value - will spread out disk I/O more evenly. - - ndirty - Ndirty gives the maximum number of dirty buffers that - bdflush can write to the disk at one time. A high value will - mean delayed, bursty I/O, while a small value can lead to - memory shortage when bdflush isn't woken up often enough. - - nrefill - This the number of buffers that bdflush will add to the list - of free buffers when refill_freelist() is called. It is - necessary to allocate free buffers beforehand, since the - buffers are often different sizes than the memory pages - and some bookkeeping needs to be done beforehand. The - higher the number, the more memory will be wasted and the - less often refill_freelist() will need to run. - - nref_dirt - When refill_freelist() comes across more than nref_dirt - dirty buffers, it will wake up bdflush. - - age_buffer and age_super - Finally, the age_buffer and age_super parameters govern the - maximum time Linux waits before writing out a dirty buffer - to disk. The value is expressed in jiffies (clockticks), the - number of jiffies per second is 100. Age_buffer is the - maximum age for data blocks, while age_super is for - filesystems meta data. +------- + +This file controls the operation of the bdflush kernel daemon. It currently +contains nine integer values, six of which are actually used by the kernel. +They are listed in table 2-2. + + +Table 2-2: Parameters in /proc/sys/vm/bdflush +.............................................................................. + Value Meaning + nfract Percentage of buffer cache dirty to activate bdflush + ndirty Maximum number of dirty blocks to write out per wake-cycle + nrefill Number of clean buffers to try to obtain each time we call refill + nref_dirt buffer threshold for activating bdflush when trying to refill + buffers. + dummy Unused + age_buffer Time for normal buffer to age before we flush it + age_super Time for superblock to age before we flush it + dummy Unused + dummy Unused +.............................................................................. + +nfract +------ + +This parameter governs the maximum number of dirty buffers in the buffer +cache. Dirty means that the contents of the buffer still have to be written to +disk (as opposed to a clean buffer, which can just be forgotten about). +Setting this to a higher value means that Linux can delay disk writes for a +long time, but it also means that it will have to do a lot of I/O at once when +memory becomes short. A lower value will spread out disk I/O more evenly. + +ndirty +------ + +Ndirty gives the maximum number of dirty buffers that bdflush can write to the +disk at one time. A high value will mean delayed, bursty I/O, while a small +value can lead to memory shortage when bdflush isn't woken up often enough. + +nrefill +------- + +This is the number of buffers that bdflush will add to the list of free +buffers when refill_freelist() is called. It is necessary to allocate free +buffers beforehand, since the buffers are often different sizes than the +memory pages and some bookkeeping needs to be done beforehand. The higher the +number, the more memory will be wasted and the less often refill_freelist() +will need to run. + +nref_dirt +--------- + +When refill_freelist() comes across more than nref_dirt dirty buffers, it will +wake up bdflush. + +age_buffer and age_super +------------------------ + +Finally, the age_buffer and age_super parameters govern the maximum time Linux +waits before writing out a dirty buffer to disk. The value is expressed in +jiffies (clockticks), the number of jiffies per second is 100. Age_buffer is +the maximum age for data blocks, while age_super is for filesystems meta data. buffermem - The three values in this file control how much memory should be - used for buffer memory. The percentage is calculated as a - percentage of total system memory. +--------- + +The three values in this file control how much memory should be used for +buffer memory. The percentage is calculated as a percentage of total system +memory. + +The values are: + +min_percent +----------- + +This is the minimum percentage of memory that should be spent on buffer +memory. - The values are: +borrow_percent +-------------- - min_percent - This is the minimum percentage of memory that should be - spent on buffer memory. +When Linux is short on memory, and the buffer cache uses more than it has been +allotted, the memory management (MM) subsystem will prune the buffer cache +more heavily than other memory to compensate. - borrow_percent - When Linux is short on memory, and the buffer cache uses more - than it has been allotted, the memory mangement (MM) subsystem - will prune the buffer cache more heavily than other memory to - compensate. +max_percent +----------- - max_percent - This is the maximum amount of memory that can be used for - buffer memory. +This is the maximum amount of memory that can be used for buffer memory. freepages - This file contains three values: min, low and high: +--------- - min - When the number of free pages in the system reaches this number, - only the kernel can allocate more memory. +This file contains three values: min, low and high: - low - If the number of free pages gets below this point, the kernel - starts swapping aggressively. +min +--- +When the number of free pages in the system reaches this number, only the +kernel can allocate more memory. - high - The kernel tries to keep up to this amount of memory free; if - memory comes below this point, the kernel gently starts swapping - in the hopes that it never has to do really aggressive swapping. +low +--- +If the number of free pages falls below this point, the kernel starts swapping +aggressively. + +high +---- +The kernel tries to keep up to this amount of memory free; if memory falls +below this point, the kernel starts gently swapping in the hopes that it never +has to do really aggressive swapping. kswapd - Kswapd is the kernel swap out daemon. That is, kswapd is that piece - of the kernel that frees memory when it gets fragmented or - full. Since every system is different, you'll probably want some - control over this piece of the system. +------ + +Kswapd is the kernel swap out daemon. That is, kswapd is that piece of the +kernel that frees memory when it gets fragmented or full. Since every system +is different, you'll probably want some control over this piece of the system. + +The file contains three numbers: + +tries_base +---------- - The file contains three numbers: +The maximum number of pages kswapd tries to free in one round is calculated +from this number. Usually this number will be divided by 4 or 8 (see +mm/vmscan.c), so it isn't as big as it looks. - tries_base - The maximum number of pages kswapd tries to free in one round is - calculated from this number. Usually this number will be divided - by 4 or 8 (see mm/vmscan.c), so it isn't as big as it looks. +When you need to increase the bandwidth to/from swap, you'll want to increase +this number. - When you need to increase the bandwidth to/from swap, you'll want - to increase this number. +tries_min +--------- - tries_min - This is the minimum number of times kswapd tries to free a page - each time it is called. Basically it's just there to make sure - that kswapd frees some pages even when it's being called with - minimum priority. +This is the minimum number of times kswapd tries to free a page each time it +is called. Basically it's just there to make sure that kswapd frees some pages +even when it's being called with minimum priority. +swap_cluster +------------ - swap_cluster - This is probably the greatest influence on system - performance. swap_cluster is the number of pages kswapd writes in - one turn. You'll want this value to be large so that kswapd does - its I/O in large chunks and the disk doesn't have to seek as - often., but you don't want it to be too large since that would - flood the request queue. +This is probably the greatest influence on system performance. + +swap_cluster is the number of pages kswapd writes in one turn. You'll want +this value to be large so that kswapd does its I/O in large chunks and the +disk doesn't have to seek as often, but you don't want it to be too large +since that would flood the request queue. overcommit_memory - This file contains one value. The following algorithm is used to - decide if there's enough memory: if the value of overcommit_memory - is positive, then there's always enough memory. This is a useful - feature, since programs often malloc() huge amounts of memory 'just - in case', while they only use a small part of it. Leaving this - value at 0 will lead to the failure of such a huge malloc(), when - in fact the system has enough memory for the program to run. - - On the other hand, enabling this feature can cause you to run out - of memory and thrash the system to death, so large and/or important - servers will want to set this value to 0. +----------------- + +This file contains one value. The following algorithm is used to decide if +there's enough memory: if the value of overcommit_memory is positive, then +there's always enough memory. This is a useful feature, since programs often +malloc() huge amounts of memory 'just in case', while they only use a small +part of it. Leaving this value at 0 will lead to the failure of such a huge +malloc(), when in fact the system has enough memory for the program to run. + +On the other hand, enabling this feature can cause you to run out of memory +and thrash the system to death, so large and/or important servers will want to +set this value to 0. pagecache - This file does exactly the same as buffermem, only this file - controls the amount of memory allowed for memory mapping and - generic caching of files. +--------- + +This file does exactly the same job as buffermem, only this file controls the +amount of memory allowed for memory mapping and generic caching of files. - You don't want the minimum level to be too low, otherwise your - system might thrash when memory is tight or fragmentation is - high. +You don't want the minimum level to be too low, otherwise your system might +thrash when memory is tight or fragmentation is high. pagetable_cache - The kernel keeps a number of page tables in a per-processor cache - (this helps a lot on SMP systems). The cache size for each - processor will be between the low and the high value. +--------------- - On a low-memory, single CPU system, you can safely set these values - to 0 so you don't waste memory. It is used on SMP systems so that - the system can perform fast pagetable allocations without having to - aquire the kernel memory lock. +The kernel keeps a number of page tables in a per-processor cache (this helps +a lot on SMP systems). The cache size for each processor will be between the +low and the high value. - For large systems, the settings are probably fine. For normal - systems they won't hurt a bit. For small systems (<16MB ram) it - might be advantageous to set both values to 0. +On a low-memory, single CPU system, you can safely set these values to 0 so +you don't waste memory. It is used on SMP systems so that the system can +perform fast pagetable allocations without having to aquire the kernel memory +lock. + +For large systems, the settings are probably fine. For normal systems they +won't hurt a bit. For small systems ( less than 16MB ram) it might be +advantageous to set both values to 0. swapctl - This file contains no less than 8 variables. All of these values - are used by kswapd. - - The first four variables sc_max_page_age, sc_page_advance, - sc_page_decline and sc_page_initial_age are used to keep track of - Linux's page aging. Page aging is a bookkeeping method to track - which pages of memory are often used, and which pages can be - swapped out without consequences. - - When a page is swapped in, it starts at sc_page_initial_age - (default 3) and when the page is scanned by kswapd, its age is - adjusted according to the following scheme: - - o If the page was used since the last time we scanned, its age - is increased by sc_page_advance (default 3) up to a - maximum of sc_max_page_age (default 20). - - o Else (meaning it wasn't used) its age is decreased by - sc_page_decline (default 1). - - When a page reaches age 0, it's ready to be swapped out. - - The next four variables sc_age_cluster_fract, sc_age_cluster_min, - sc_pageout_weight and sc_bufferout_weight, can be used to control - kswapd's aggressiveness in swapping out pages. - - Sc_age_cluster_fract is used to calculate how many pages from a - process are to be scanned by kswapd. The formula used is - - sc_age_cluster_fract - -------------------- * resident set size - 1024 =20 - - So if you want kswapd to scan the whole process, - sc_age_cluster_fract needs to have a value of 1024. The minimum - number of pages kswapd will scan is represented by - sc_age_cluster_min, this is done so kswapd will also scan small - processes. - - The values of sc_pageout_weight and sc_bufferout_weight are used - to control how many tries kswapd will make in order to swap out - one page/buffer. These values can be used to fine-tune the ratio - between user pages and buffer/cache memory. When you find that - your Linux system is swapping out too many process pages in order - to satisfy buffer memory demands, you might want to either - increase sc_bufferout_weight, or decrease the value of - sc_pageout_weight. - -3.6 /proc/sys/dev - Device specific parameters - -Currently there is only support for CDROM drives, but other drivers may -wish to register themselves in here in the future. The cdrom/ directory -contains several files that either control or supply information about -the CDROM subsystem. - ->cat /proc/sys/dev/cdrom/info -CD-ROM information, Id: cdrom.c 3.04 1999/09/12 - -drive name: hdd hdc hdb hda -drive speed: 32 24 10 0 -drive # of slots: 1 1 1 1 -Can close tray: 1 1 1 1 -Can open tray: 1 1 1 1 -Can lock tray: 1 1 1 1 -Can change speed: 1 1 1 1 -Can select disk: 0 0 0 0 -Can read multisession: 1 1 1 1 -Can read MCN: 1 1 1 1 -Reports media changed: 1 1 1 1 -Can play audio: 1 1 1 1 -Can write CD-R: 0 1 0 0 -Can write CD-RW: 0 1 0 0 -Can read DVD: 0 0 0 1 -Can write DVD-R: 0 0 0 0 -Can write DVD-RAM: 0 0 0 0 - -You see four drives and their lists of features. These are all ATAPI -drives - SCSI drives will be numbered sr0, sr1, and so forth. - -The remaining files all set options in the driver. - -autoclose - Close the drive tray when the drive is accessed. - -autoeject - Eject the tray when the drive is umounted. - -check_media - Verify the media type when opening the device. This is generally - meant for audio CD's. - -debug - Print debugging messages. - -lock - Lock the tray when the drive is in use. - - -3.7 /proc/sys/sunrpc - Remote procedure calls - -This directory contains four files, which enable or disable debugging -for the RPC functions NFS, NFS-daemon, RPC and NLM. The default values -are 0. They can be set to one, to turn debugging on. (The default -value is 0 for each) - -3.8 /proc/sys/net - Networking stuff - -The interface to the networking parts of the kernel is located in -/proc/sys/net. The table below shows all possible subdirectories. You -may see only some of them, depending on the configuration of your -kernel: - -+-------------------------------------------------------------+ -| core General parameter |appletalk Appletalk protocol | -| unix Unix domain sockets |netrom NET/ROM | -| 802 E802 protocol |ax25 AX25 | -| ethernet Ethernet protocol |rose X.25 PLP layer | -| ipv4 IP version 4 |x25 X.25 protocol | -| ipx IPX |token-ring IBM token ring | -| bridge Bridging |decnet DEC net | -| ipv6 IP version 6 | | -+-------------------------------------------------------------+ - -We will concentrate on IP networking here. As AX15, X.25, and DEC Net -are only minor players in the Linux world, we'll skip them in this -chapter. You'll find some short info to Appletalk and IPX further down -in section 3.10 and 3.11. Please look in the online documentation and -the kernel source to get a detailed view of the parameters for those -protocols. In this section we'll discuss the subdirectories printed in -bold letters in the table above. As default values are suitable for -most needs, there is no need to change these values. +------- + +This file contains no less than 8 variables. All of these values are used by +kswapd. + +The first four variables +* sc_max_page_age, +* sc_page_advance, +* sc_page_decline and +* sc_page_initial_age +are used to keep track of Linux's page aging. Page aging is a bookkeeping +method to track which pages of memory are often used, and which pages can be +swapped out without consequences. + +When a page is swapped in, it starts at sc_page_initial_age (default 3) and +when the page is scanned by kswapd, its age is adjusted according to the +following scheme: + +* If the page was used since the last time we scanned, its age is increased + by sc_page_advance (default 3). Where the maximum value is given by + sc_max_page_age (default 20). +* Otherwise (meaning it wasn't used) its age is decreased by sc_page_decline + (default 1). + +When a page reaches age 0, it's ready to be swapped out. + +The variables sc_age_cluster_fract, sc_age_cluster_min, sc_pageout_weight and +sc_bufferout_weight, can be used to control kswapd's aggressiveness in +swapping out pages. + +Sc_age_cluster_fract is used to calculate how many pages from a process are to +be scanned by kswapd. The formula used is + +(sc_age_cluster_fract divided by 1024) times resident set size + +So if you want kswapd to scan the whole process, sc_age_cluster_fract needs to +have a value of 1024. The minimum number of pages kswapd will scan is +represented by sc_age_cluster_min, which is done so that kswapd will also scan +small processes. + +The values of sc_pageout_weight and sc_bufferout_weight are used to control +how many tries kswapd will make in order to swap out one page/buffer. These +values can be used to fine-tune the ratio between user pages and buffer/cache +memory. When you find that your Linux system is swapping out too many process +pages in order to satisfy buffer memory demands, you may want to either +increase sc_bufferout_weight, or decrease the value of sc_pageout_weight. + +2.5 /proc/sys/dev - Device specific parameters +---------------------------------------------- + +Currently there is only support for CDROM drives, and for those, there is only +one read-only file containing information about the CD-ROM drives attached to +the system: + + >cat /proc/sys/dev/cdrom/info + CD-ROM information, Id: cdrom.c 2.55 1999/04/25 + + drive name: sr0 hdb + drive speed: 32 40 + drive # of slots: 1 0 + Can close tray: 1 1 + Can open tray: 1 1 + Can lock tray: 1 1 + Can change speed: 1 1 + Can select disk: 0 1 + Can read multisession: 1 1 + Can read MCN: 1 1 + Reports media changed: 1 1 + Can play audio: 1 1 + + +You see two drives, sr0 and hdb, along with a list of their features. + +2.6 /proc/sys/sunrpc - Remote procedure calls +--------------------------------------------- + +This directory contains four files, which enable or disable debugging for the +RPC functions NFS, NFS-daemon, RPC and NLM. The default values are 0. They can +be set to one to turn debugging on. (The default value is 0 for each) + +2.7 /proc/sys/net - Networking stuff +------------------------------------ + +The interface to the networking parts of the kernel is located in +/proc/sys/net. Table 2-3 shows all possible subdirectories. You may see only +some of them, depending on your kernel's configuration. + + +Table 2-3: Subdirectories in /proc/sys/net +.............................................................................. + Directory Content Directory Content + core General parameter appletalk Appletalk protocol + unix Unix domain sockets netrom NET/ROM + 802 E802 protocol ax25 AX25 + ethernet Ethernet protocol rose X.25 PLP layer + ipv4 IP version 4 x25 X.25 protocol + ipx IPX token-ring IBM token ring + bridge Bridging decnet DEC net + ipv6 IP version 6 +.............................................................................. + +We will concentrate on IP networking here. Since AX15, X.25, and DEC Net are +only minor players in the Linux world, we'll skip them in this chapter. You'll +find some short info on Appletalk and IPX further on in this chapter. Review +the online documentation and the kernel source to get a detailed view of the +parameters for those protocols. In this section we'll discuss the +subdirectories printed in bold letters in the table above. As default values +are suitable for most needs, there is no need to change these values. /proc/sys/net/core - Network core options +----------------------------------------- rmem_default - The default setting of the socket receive buffer in bytes. +------------ + +The default setting of the socket receive buffer in bytes. rmem_max - The maximum receive socket buffer size in bytes. +-------- + +The maximum receive socket buffer size in bytes. wmem_default - The default setting (in bytes) of the socket send buffer. +------------ + +The default setting (in bytes) of the socket send buffer. wmem_max - The maximum send socket buffer size in bytes. +-------- + +The maximum send socket buffer size in bytes. message_burst and message_cost - These parameters are used to limit the warning messages written to - the kernel log from the networking code. They enforce a rate limit - to make a denial-of-service attack impossible. The higher the - message_cost factor is, the less messages will be - written. Message_burst controls when messages will be dropped. The - default settings limit warning messages to one every five seconds. +------------------------------ + +These parameters are used to limit the warning messages written to the kernel +log from the networking code. They enforce a rate limit to make a +denial-of-service attack impossible. A higher message_cost factor, results in +fewer messages that will be written. Message_burst controls when messages will +be dropped. The default settings limit warning messages to one every five +seconds. netdev_max_backlog - Maximal number of packets, queued on INPUT side, when the interface - receives packets faster than kernel can process them. +------------------ + +Maximum number of packets, queued on the INPUT side, when the interface +receives packets faster than kernel can process them. optmem_max - Maximum ancillary buffer size allowed per socket. Ancillary data is - a sequence of struct cmsghdr structures with appended data. +---------- + +Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence +of struct cmsghdr structures with appended data. -/proc/sys/net/unix - Parameters for UNIX domain sockets +/proc/sys/net/unix - Parameters for Unix domain sockets +------------------------------------------------------- -There are only two files in this subdirectory. They control the delays -for deleting and destroying socket descriptors. +There are only two files in this subdirectory. They control the delays for +deleting and destroying socket descriptors. -3.9 /proc/sys/net/ipv4 - IPV4 settings +2.8 /proc/sys/net/ipv4 - IPV4 settings +-------------------------------------- -IP version 4 is still the most used protocol in Unix networking. It -will be replaced by IP version 6 in the next couple of years, but for -the moment it's the de facto standard for the internet and is used in -most networking environments around the world. Because of the -importance of this protocol, we'll have a deeper look into the subtree -controlling the behavior of the IPv4 subsystem of the Linux kernel. +IP version 4 is still the most used protocol in Unix networking. It will be +replaced by IP version 6 in the next couple of years, but for the moment it's +the de facto standard for the internet and is used in most networking +environments around the world. Because of the importance of this protocol, +we'll have a deeper look into the subtree controlling the behavior of the IPv4 +subsystem of the Linux kernel. -Let's start with the entries in /proc/sys/net/ipv4 itself. +Let's start with the entries in /proc/sys/net/ipv4. ICMP settings +------------- icmp_echo_ignore_all and icmp_echo_ignore_broadcasts - Turn on (1) or off (0), if the kernel should ignore all ICMP ECHO - requests, or just those to broadcast and multicast addresses. +---------------------------------------------------- - Please note that if you accept ICMP echo requests with a - broadcast/multicast destination address your network may be used - as an exploder for denial of service packet flooding attacks to - other hosts. +Turn on (1) or off (0), if the kernel should ignore all ICMP ECHO requests, or +just those to broadcast and multicast addresses. -icmp_destunreach_rate, icmp_echoreply_rate, -icmp_paramprob_rate and icmp_timeexeed_rate - Sets limits for sending ICMP packets to specific targets. A value of - zero disables all limiting. Any positive value sets the maximum - package rate in hundredths of a second (on Intel systems). +Please note that if you accept ICMP echo requests with a broadcast/multi\-cast +destination address your network may be used as an exploder for denial of +service packet flooding attacks to other hosts. + +icmp_destunreach_rate, icmp_echoreply_rate, icmp_paramprob_rate and icmp_timeexeed_rate +--------------------------------------------------------------------------------------- + +Sets limits for sending ICMP packets to specific targets. A value of zero +disables all limiting. Any positive value sets the maximum package rate in +hundredth of a second (on Intel systems). IP settings +----------- ip_autoconfig - This file contains one, if the host got its IP configuration by - RARP, BOOTP, DHCP or a similar mechanism. Otherwise it is zero. +------------- + +This file contains the number one if the host received its IP configuration by +RARP, BOOTP, DHCP or a similar mechanism. Otherwise it is zero. ip_default_ttl - TTL (Time To Live) for IPv4 interfaces. This is simply the - maximum number of hops a packet may travel. +-------------- + +TTL (Time To Live) for IPv4 interfaces. This is simply the maximum number of +hops a packet may travel. ip_dynaddr - Enable dynamic socket address rewriting on interface address change. This - is useful for dialup interface with changing IP addresses. +---------- + +Enable dynamic socket address rewriting on interface address change. This is +useful for dialup interface with changing IP addresses. ip_forward - Enable or disable forwarding of IP packages between interfaces. A - change of this value resets all other parameters to their default - values. They differ if the kernel is configured as host or router. +---------- + +Enable or disable forwarding of IP packages between interfaces. Changing this +value resets all other parameters to their default values. They differ if the +kernel is configured as host or router. ip_local_port_range - Range of ports used by TCP and UDP to choose the local - port. Contains two numbers, the first number is the lowest port, - the second number the highest local port. Default is 1024-4999. - Should be changed to 32768-61000 for high-usage systems. +------------------- + +Range of ports used by TCP and UDP to choose the local port. Contains two +numbers, the first number is the lowest port, the second number the highest +local port. Default is 1024-4999. Should be changed to 32768-61000 for +high-usage systems. ip_no_pmtu_disc - Global switch to turn path MTU discovery off. It can also be set - on a per socket basis by the applications or on a per route - basis. +--------------- + +Global switch to turn path MTU discovery off. It can also be set on a per +socket basis by the applications or on a per route basis. ip_masq_debug - Enable/disable debugging of IP masquerading. +------------- +Enable/disable debugging of IP masquerading. IP fragmentation settings +------------------------- ipfrag_high_trash and ipfrag_low_trash - Maximum memory used to reassemble IP fragments. When - ipfrag_high_thresh bytes of memory is allocated for this purpose, - the fragment handler will toss packets until ipfrag_low_thresh is - reached. +-------------------------------------- +Maximum memory used to reassemble IP fragments. When ipfrag_high_thresh bytes +of memory is allocated for this purpose, the fragment handler will toss +packets until ipfrag_low_thresh is reached. ipfrag_time - Time in seconds to keep an IP fragment in memory. +----------- + +Time in seconds to keep an IP fragment in memory. TCP settings +------------ tcp_retrans_collapse - Bug-to-bug compatibility with some broken printers. On retransmit - try to send bigger packets to work around bugs in certain TCP - stacks. Can be turned off by setting it to zero. +-------------------- + +Bug-to-bug compatibility with some broken printers. On retransmit, try to send +larger packets to work around bugs in certain TCP stacks. Can be turned off by +setting it to zero. tcp_keepalive_probes - Number of keep alive probes TCP sends out, until it decides that the - connection is broken. +-------------------- + +Number of keep alive probes TCP sends out, until it decides that the +connection is broken. tcp_keepalive_time - How often TCP sends out keep alive messages, when keep alive is - enabled. The default is 2 hours. +------------------ + +How often TCP sends out keep alive messages, when keep alive is enabled. The +default is 2 hours. tcp_syn_retries - Number of times initial SYNs for a TCP connection attempt will be - retransmitted. Should not be higher than 255. This is only the - timeout for outgoing connections, for incoming connections the - number of retransmits is defined by tcp_retries1. +--------------- + +Number of times initial SYNs for a TCP connection attempt will be +retransmitted. Should not be higher than 255. This is only the timeout for +outgoing connections, for incoming connections the number of retransmits is +defined by tcp_retries1. tcp_sack - Enable select acknowledgments after RFC2018. +-------- + +Enable select acknowledgments after RFC2018. tcp_timestamps - Enable timestamps as defined in RFC1323. +-------------- + +Enable timestamps as defined in RFC1323. tcp_stdurg - Enable the strict RFC793 interpretation of the TCP urgent pointer - field. The default is to use the BSD compatible interpretation - of the urgent pointer pointing to the first byte after the urgent - data. The RFC793 interpretation is to have it point to the last - byte of urgent data. Enabling this option may lead to - interoperatibility problems. Disabled by default. +---------- + +Enable the strict RFC793 interpretation of the TCP urgent pointer field. The +default is to use the BSD compatible interpretation of the urgent pointer +pointing to the first byte after the urgent data. The RFC793 interpretation is +to have it point to the last byte of urgent data. Enabling this option may +lead to interoperatibility problems. Disabled by default. tcp_syncookies - Only valid when the kernel was compiled with - CONFIG_SYNCOOKIES. Send out syncookies when the syn backlog queue - of a socket overflows. This is to prevent against the common 'syn - flood attack'. Disabled by default. +-------------- + +Only valid when the kernel was compiled with CONFIG_SYNCOOKIES. Send out +syncookies when the syn backlog queue of a socket overflows. This is to ward +off the common 'syn flood attack'. Disabled by default. - Note that the concept of a socket backlog is abandoned, this - means the peer may not receive reliable error messages from an - over loaded server with syncookies enabled. +Note that the concept of a socket backlog is abandoned. This means the peer +may not receive reliable error messages from an over loaded server with +syncookies enabled. tcp_window_scaling - Enable window scaling as defined in RFC1323. +------------------ + +Enable window scaling as defined in RFC1323. tcp_fin_timeout - How many seconds to wait for a final FIN before the socket is - always closed. This is strictly a violation of the TCP - specification, but required to prevent denial-of-service attacks. +--------------- + +The length of time in seconds it takes to receive a final FIN before the +socket is always closed. This is strictly a violation of the TCP +specification, but required to prevent denial-of-service attacks. tcp_max_ka_probes - How many keepalive probes are sent per slow timer run. Shouldn't be - set too high to prevent bursts. +----------------- + +Indicates how many keep alive probes are sent per slow timer run. Should not +be set too high to prevent bursts. tcp_max_syn_backlog - Length of the per socket backlog queue. Since Linux 2.2 the backlog - specified in listen(2) only specifies the length of the backlog - queue of already established sockets. When more connection requests - arrive Linux starts to drop packets. When syncookies are enabled - the packets are still answered and the maximum queue is effectively - ignored. +------------------- + +Length of the per socket backlog queue. Since Linux 2.2 the backlog specified +in listen(2) only specifies the length of the backlog queue of already +established sockets. When more connection requests arrive Linux starts to drop +packets. When syncookies are enabled the packets are still answered and the +maximum queue is effectively ignored. tcp_retries1 - Defines how often an answer to a TCP connection request is - retransmitted before giving up. +------------ + +Defines how often an answer to a TCP connection request is retransmitted +before giving up. tcp_retries2 - Defines how often a TCP packet is retransmitted before giving up. +------------ -Interface specific settings +Defines how often a TCP packet is retransmitted before giving up. -In the directory /proc/sys/net/ipv4/conf you'll find one subdirectory -for each interface the system knows about and one directory calls -all. Changes in the all subdirectory affect all interfaces, where -changes in the other subdirectories affect only one interface. +Interface specific settings +--------------------------- -All directories have the same entries: +In the directory /proc/sys/net/ipv4/conf you'll find one subdirectory for each +interface the system knows about and one directory calls all. Changes in the +all subdirectory affect all interfaces, whereas changes in the other +subdirectories affect only one interface. All directories have the same +entries: accept_redirects - This switch decides if the kernel accepts ICMP redirect messages - or not. The default is 'yes', if the kernel is configured for a - regular host; and 'no' for a router configuration. +---------------- + +This switch decides if the kernel accepts ICMP redirect messages or not. The +default is 'yes' if the kernel is configured for a regular host and 'no' for a +router configuration. accept_source_route - Should source routed packages be accepted or declined. The - default is dependent on the kernel configuration. It's 'yes' for - routers and 'no' for hosts. +------------------- + +Should source routed packages be accepted or declined. The default is +dependent on the kernel configuration. It's 'yes' for routers and 'no' for +hosts. bootp_relay - Accept packets with source address 0.b.c.d destined not to this - host as local ones. It is supposed that BOOTP relay daemon will - catch and forward such packets. +~~~~~~~~~~~ + +Accept packets with source address 0.b.c.d with destinations not to this host +as local ones. It is supposed that a BOOTP relay daemon will catch and forward +such packets. - The default is 'no', as this feature is not implemented yet - (kernel version 2.2.0-pre?). +The default is 0, since this feature is not implemented yet (kernel version +2.2.12). forwarding - Enable or disable IP forwarding on this interface. +---------- + +Enable or disable IP forwarding on this interface. log_martians - Log packets with source addresses with no known route to kernel log. +------------ + +Log packets with source addresses with no known route to kernel log. mc_forwarding - Do multicast routing. The kernel needs to be compiled with - CONFIG_MROUTE and a multicast routing daemon is required. +------------- + +Do multicast routing. The kernel needs to be compiled with CONFIG_MROUTE and a +multicast routing daemon is required. proxy_arp - Do (1) or don't (0) do proxy ARP. +--------- + +Does (1) or does not (0) perform proxy ARP. rp_filter - Integer value deciding if source validation should be made. - 1 means yes, 0 means no. Disabled by default, but - local/broadcast address spoofing is always on. +--------- - If you set this to 1 on a router that is the only connection - for a network to the net , it evidently prevents spoofing attacks - against your internal networks (external addresses can still be - spoofed), without the need for additional firewall rules. +Integer value determines if a source validation should be made. 1 means yes, 0 +means no. Disabled by default, but local/broadcast address spoofing is always +on. + +If you set this to 1 on a router that is the only connection for a network to +the net, it will prevent spoofing attacks against your internal networks +(external addresses can still be spoofed), without the need for additional +firewall rules. secure_redirects - Accept ICMP redirect messages only for gateways, listed in - default gateway list. Enabled by default. +---------------- + +Accept ICMP redirect messages only for gateways, listed in default gateway +list. Enabled by default. shared_media - If it is not set the kernel does not assume that different subnets - on this device can communicate directly. Default setting is 'yes'. +------------ + +If it is not set the kernel does not assume that different subnets on this +device can communicate directly. Default setting is 'yes'. send_redirects - Determines if or if not to send ICMP redirects to other hosts. +-------------- +Determines whether to send ICMP redirects to other hosts. Routing settings +---------------- -The directory /proc/sys/net/ipv4/route contains several file to -control routing issues. +The directory /proc/sys/net/ipv4/route contains several file to control +routing issues. error_burst and error_cost - These parameters are used to limit the warning messages written to - the kernel log from the routing code. The higher the error_cost - factor is, the fewer messages will be written. Error_burst controls - when messages will be dropped. The default settings limit warning - messages to one every five seconds. +-------------------------- + +These parameters are used to limit the warning messages written to the kernel +log from the routing code. The higher the error_cost factor is, the fewer +messages will be written. Error_burst controls when messages will be dropped. +The default settings limit warning messages to one every five seconds. flush - Writing to this file results in a flush of the routing cache. +----- + +Writing to this file results in a flush of the routing cache. gc_elastic, gc_interval, gc_min_interval, gc_tresh, gc_timeout - Values to control the frequency and behavior of the garbage - collection algorithm for the routing cache. +-------------------------------------------------------------- + +Values to control the frequency and behavior of the garbage collection +algorithm for the routing cache. max_size - Maximum size of the routing cache. Old entries will be purged - once the cache has this size. +-------- + +Maximum size of the routing cache. Old entries will be purged once the cache +reached has this size. max_delay, min_delay - Delays for flushing the routing cache. +-------------------- + +Delays for flushing the routing cache. redirect_load, redirect_number - Factors which determine if more ICPM redirects should be sent to - a specific host. No redirects will be sent once the load limit or - the maximum number of redirects has been reached. +------------------------------ + +Factors which determine if more ICPM redirects should be sent to a specific +host. No redirects will be sent once the load limit or the maximum number of +redirects has been reached. redirect_silence +---------------- - Timeout for redirects. After this period redirects will be sent - again, even if this has been stopped, because the load or number - limit has been reached. +Timeout for redirects. After this period redirects will be sent again, even if +this has been stopped, because the load or number limit has been reached. Network Neighbor handling +------------------------- -Settings about how to handle connections with direct neighbors (nodes -attached to the same link) can be found in the directory -/proc/sys/net/ipv4/neigh. +Settings about how to handle connections with direct neighbors (nodes attached +to the same link) can be found in the directory /proc/sys/net/ipv4/neigh. -As we saw it in the conf directory, there is a default subdirectory -which holds the default values, and one directory for each -interface. The contents of the directories are identical, with the -single exception that the default settings contain additional options -to set garbage collection parameters. +As we saw it in the conf directory, there is a default subdirectory which +holds the default values, and one directory for each interface. The contents +of the directories are identical, with the single exception that the default +settings contain additional options to set garbage collection parameters. In the interface directories you'll find the following entries: base_reachable_time - A base value used for computing the random reachable time value - as specified in RFC2461. +------------------- + +A base value used for computing the random reachable time value as specified +in RFC2461. retrans_time - The time, expressed in jiffies (1/100 sec), between retransmitted - Neighbor Solicitation messages. Used for address resolution and to - determine if a neighbor is unreachable. +------------ + +The time, expressed in jiffies (1/100 sec), between retransmitted Neighbor +Solicitation messages. Used for address resolution and to determine if a +neighbor is unreachable. unres_qlen - Maximum queue length for a pending arp request - how many packets - are accepted from other layers while the arp address is still - resolved. +---------- + +Maximum queue length for a pending arp request - the number of packets which +are accepted from other layers while the ARP address is still resolved. anycast_delay - Maximum for random delay of answers to neighbor solicitation - messages in jiffies (1/100 sec). Not yet implemented (Linux does - not have anycast support yet). +------------- + +Maximum for random delay of answers to neighbor solicitation messages in +jiffies (1/100 sec). Not yet implemented (Linux does not have anycast support +yet). ucast_solicit - Maximum number of retries for unicast solicitation. +------------- + +Maximum number of retries for unicast solicitation. mcast_solicit - Maximum number of retries for multicast solicitation. +------------- + +Maximum number of retries for multicast solicitation. delay_first_probe_time - Delay for the first time probe if the neighbor is reachable. (see - gc_stale_time). +---------------------- + +Delay for the first time probe if the neighbor is reachable. (see +gc_stale_time) locktime - An ARP/neighbor entry is only replaced with a new one if the old - is at least locktime old. This prevents ARP cache thrashing. +-------- + +An ARP/neighbor entry is only replaced with a new one if the old is at least +locktime old. This prevents ARP cache thrashing. proxy_delay - Maximum time (real time is random [0..proxytime]) before - answering to an arp request for which we have an proxy arp entry. - In some cases, this is used to prevent network flooding. +----------- + +Maximum time (real time is random [0..proxytime]) before answering to an ARP +request for which we have an proxy ARP entry. In some cases, this is used to +prevent network flooding. proxy_qlen - Maximum queue length of the delayed proxy arp timer (see - proxy_delay). +---------- + +Maximum queue length of the delayed proxy arp timer. (see proxy_delay). app_solcit - Determines the number of requests to send to the user level arp - daemon. 0 to turn off. +---------- + +Determines the number of requests to send to the user level ARP daemon. Use 0 +to turn off. gc_stale_time - Determines how often to check for stale ARP entries. After an ARP - entry is stale it will be resolved again (useful when an IP address - migrates to another machine). When ucast_solicit is > 0 it first - tries to send an ARP packet directly to the known host, when that - fails and mcast_solicit is > 0, an ARP request is broadcasted. +------------- -3.10 Appletalk +Determines how often to check for stale ARP entries. After an ARP entry is +stale it will be resolved again (which is useful when an IP address migrates +to another machine). When ucast_solicit is greater than 0 it first tries to +send an ARP packet directly to the known host When that fails and +mcast_solicit is greater than 0, an ARP request is broadcasted. -The /proc/sys/net/appletalk directory holds the Appletalk -configuration data when Appletalk is loaded. The configurable -parameters are: +2.9 Appletalk +------------- + +The /proc/sys/net/appletalk directory holds the Appletalk configuration data +when Appletalk is loaded. The configurable parameters are: aarp-expiry-time - The amount of time we keep an AARP entry before expiring - it. Used to age out old hosts. +---------------- + +The amount of time we keep an ARP entry before expiring it. Used to age out +old hosts. aarp-resolve-time - The amount of time we will spend trying to resolve an Appletalk - address. +----------------- + +The amount of time we will spend trying to resolve an Appletalk address. aarp-retransmit-limit - The number of times we will retransmit a query before giving up. +--------------------- + +The number of times we will retransmit a query before giving up. aarp-tick-time - Controls the rate at which expiries are checked. - - -The directory /proc/net/appletalk holds the list of active appletalk -sockets on a machine. - -The fields indicate the DDP type, the local address (in network:node -format) the remote address, the size of the transmit pending queue, -the size of the received queue (bytes waiting for applications to -read) the state and the uid owning the socket. - -/proc/net/atalk_iface lists all the interfaces configured for -appletalk.It shows the name of the interface, its appletalk address, -the network range on that ad- dress (or network number for phase 1 -networks), and the status of the interface. - -/proc/net/atalk_route lists each known network route. It lists the -target (network) that the route leads to, the router (may be directly -connected), the route flags, and the device the route is via. - -3.11 IPX - -The IPX protocol has no tunable values in /proc/sys/net. - -The IPX protocol does, however, provide /proc/net/ipx. This lists each -IPX socket giving the local and remote addresses in Novell format -(that is network:node:port). In accordance with the strange Novell -tradition, everything but the port is in hex. Not_Connected is -displayed for sockets that are not tied to a specific remote -address. The Tx and Rx queue sizes indicate the number of bytes -pending for transmit and receive. The state indicates the state the -socket is in and the uid is the owning uid of the socket. - -The /proc/net/ipx_interface file lists all IPX interfaces. For each -interface it gives the network number, the node number, and indicates -if the network is the primary network. It also indicates which device it is bound to (or -Internal for internal networks) and the Frame Type if -appropriate. Linux supports 802.3, 802.2, 802.2 SNAP and DIX (Blue -Book) ethernet framing for IPX. - -The /proc/net/ipx_route table holds a list of IPX routes. For each -route it gives the destination network, the router node (or Directly) -and the network address of the router (or Connected) for internal -networks. +-------------- + +Controls the rate at which expires are checked. + +The directory /proc/net/appletalk holds the list of active Appletalk sockets +on a machine. + +The fields indicate the DDP type, the local address (in network:node format) +the remote address, the size of the transmit pending queue, the size of the +received queue (bytes waiting for applications to read) the state and the uid +owning the socket. + +/proc/net/atalk_iface lists all the interfaces configured for appletalk.It +shows the name of the interface, its Appletalk address, the network range on +that address (or network number for phase 1 networks), and the status of the +interface. + +/proc/net/atalk_route lists each known network route. It lists the target +(network) that the route leads to, the router (may be directly connected), the +route flags, and the device the route is using. + +2.10 IPX +-------- + +The IPX protocol has no tunable values in proc/sys/net. + +The IPX protocol does, however, provide proc/net/ipx. This lists each IPX +socket giving the local and remote addresses in Novell format (that is +network:node:port). In accordance with the strange Novell tradition, +everything but the port is in hex. Not_Connected is displayed for sockets that +are not tied to a specific remote address. The Tx and Rx queue sizes indicate +the number of bytes pending for transmission and reception. The state +indicates the state the socket is in and the uid is the owning uid of the +socket. + +The /proc/net/ipx_interface file lists all IPX interfaces. For each interface +it gives the network number, the node number, and indicates if the network is +the primary network. It also indicates which device it is bound to (or +Internal for internal networks) and the Frame Type if appropriate. Linux +supports 802.3, 802.2, 802.2 SNAP and DIX (Blue Book) ethernet framing for +IPX. + +The /proc/net/ipx_route table holds a list of IPX routes. For each route it +gives the destination network, the router node (or Directly) and the network +address of the router (or Connected) for internal networks. + +------------------------------------------------------------------------------ +Summary +------------------------------------------------------------------------------ +Certain aspects of kernel behavior can be modified at runtime, without the +need to recompile the kernel, or even to reboot the system. The files in the +/proc/sys tree can not only be read, but also modified. You can use the echo +command to write value into these files, thereby changing the default settings +of the kernel. +------------------------------------------------------------------------------ + + + + + + + diff --git a/Documentation/filesystems/smbfs.txt b/Documentation/filesystems/smbfs.txt index 3655240e0..f673ef0de 100644 --- a/Documentation/filesystems/smbfs.txt +++ b/Documentation/filesystems/smbfs.txt @@ -2,47 +2,7 @@ Smbfs is a filesystem that implements the SMB protocol, which is the protocol used by Windows for Workgroups, Windows 95 and Windows NT. Smbfs was inspired by Samba, the program written by Andrew Tridgell that turns any Unix host into a file server for DOS or Windows clients. -See ftp://nimbus.anu.edu.au/pub/tridge/samba/ for this interesting -program suite and much more information on SMB, NetBIOS over TCP/IP, -and explanations for concepts like netbios name or share. -To use smbfs, you must first install the Samba package (Samba-1.9.18p1 or -later). This package includes the special smbmount utility needed to mount -smbfs volumes. Refer to the smbmount(8) and smbmnt(8) manpages for the -details regarding smbfs mounts. - -The smbmount utility reads the Samba smb.conf config file for some of its -options, and at least one of these is important for smbfs operation. You -should enable the TCP_NODELAY socket option, or else directory listings -will be dramatically slower (under Win NT at least). - -Mount-Time Options -Windows 95 has several bugs that affect SMB operations, and smbfs includes -work-arounds for all of the bugs found (so far, at least.) These can be -enabled at compile-time with the CONFIG_SMB_WIN95 kernel option. - -Unfortunately, some of the Win 95 work-arounds interact with Win NT bugs, -so if you're using several different types of servers on your network you -probably want to enable the work-arounds at mount time. To do this, answer -`N' to the CONFIG_SMB_WIN95 option, and add the needed options listed below -to the file mode argument of the mount command for the Win 95 servers. - -Option Value Effect -Identify Win 95 Server 1 Enables bug fixes -Use Core Attributes 2 Speeds up directory scans, only mtime -Use Dir Attributes 4 Alternate way to get file attributes - -To apply the options, sum the values and prepend it to the file mode. For -example, to use options 1 and 2 with file mode 755, you would specify 3755: - - mount /mnt/tmp -f 3755 - -Smbfs will print a message at mount time confirming the selected options. -Note that _only_ Windows 95 servers require special treatment; using the -"core attributes" option with Win NT will give trash timestamp values. - -To summarize, if your network includes both Win 95 and NT servers: -(1) Do _not_ enable the CONFIG_SMB_WIN95 kernel option - -(2) Add the desired work-around options to the mount command for your - Win 95 server(s). +Smbfs is a SMB client, but uses parts of samba for it's operation. For +more info on samba, including documentation, please go to +http://www.samba.org/ and then on to your nearest mirror. |