Documentation/sysctl/net.txt

   1 Documentation for /proc/sys/net/*       kernel version 2.4.0-test11-pre4
   2         (c) 1999                Terrehon Bowden <terrehon@pacbell.net>
   3                                 Bodo Bauer <bb@ricochet.net>
   4         (c) 2000                Jorge Nerin <comandante@zaralinux.com>
   5         (c) 2009                Shen Feng <shen@cn.fujitsu.com>
   6
   7 For general info and legal blurb, please look in README.
   8
   9 ==============================================================
  10
  11 This file contains the documentation for the sysctl files in
  12 /proc/sys/net and is valid for Linux kernel version 2.4.0-test11-pre4.
  13
  14 The interface  to  the  networking  parts  of  the  kernel  is  located  in
  15 /proc/sys/net. The following table shows all possible subdirectories.You may
  16 see only some of them, depending on your kernel's configuration.
  17
  18
  19 Table : Subdirectories in /proc/sys/net
  20 ..............................................................................
  21  Directory Content             Directory  Content
  22  core      General parameter   appletalk  Appletalk protocol
  23  unix      Unix domain sockets netrom     NET/ROM
  24  802       E802 protocol       ax25       AX25
  25  ethernet  Ethernet protocol   rose       X.25 PLP layer
  26  ipv4      IP version 4        x25        X.25 protocol
  27  ipx       IPX                 token-ring IBM token ring
  28  bridge    Bridging            decnet     DEC net
  29  ipv6      IP version 6
  30 ..............................................................................
  31
  32 1. /proc/sys/net/core - Network core options
  33 -------------------------------------------------------
  34
  35 rmem_default
  36 ------------
  37
  38 The default setting of the socket receive buffer in bytes.
  39
  40 rmem_max
  41 --------
  42
  43 The maximum receive socket buffer size in bytes.
  44
  45 wmem_default
  46 ------------
  47
  48 The default setting (in bytes) of the socket send buffer.
  49
  50 wmem_max
  51 --------
  52
  53 The maximum send socket buffer size in bytes.
  54
  55 message_burst and message_cost
  56 ------------------------------
  57
  58 These parameters  are used to limit the warning messages written to the kernel
  59 log from  the  networking  code.  They  enforce  a  rate  limit  to  make  a
  60 denial-of-service attack  impossible. A higher message_cost factor, results in
  61 fewer messages that will be written. Message_burst controls when messages will
  62 be dropped.  The  default  settings  limit  warning messages to one every five
  63 seconds.
  64
  65 warnings
  66 --------
  67
  68 This controls console messages from the networking stack that can occur because
  69 of problems on the network like duplicate address or bad checksums. Normally,
  70 this should be enabled, but if the problem persists the messages can be
  71 disabled.
  72
  73 netdev_budget
  74 -------------
  75
  76 Maximum number of packets taken from all interfaces in one polling cycle (NAPI
  77 poll). In one polling cycle interfaces which are registered to polling are
  78 probed in a round-robin manner. The limit of packets in one such probe can be
  79 set per-device via sysfs class/net/<device>/weight .
  80
  81 netdev_max_backlog
  82 ------------------
  83
  84 Maximum number  of  packets,  queued  on  the  INPUT  side, when the interface
  85 receives packets faster than kernel can process them.
  86
  87 netdev_tstamp_prequeue
  88 ----------------------
  89
  90 If set to 0, RX packet timestamps can be sampled after RPS processing, when
  91 the target CPU processes packets. It might give some delay on timestamps, but
  92 permit to distribute the load on several cpus.
  93
  94 If set to 1 (default), timestamps are sampled as soon as possible, before
  95 queueing.
  96
  97 optmem_max
  98 ----------
  99
 100 Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence
 101 of struct cmsghdr structures with appended data.
 102
 103 2. /proc/sys/net/unix - Parameters for Unix domain sockets
 104 -------------------------------------------------------
 105
 106 There is only one file in this directory.
 107 unix_dgram_qlen limits the max number of datagrams queued in Unix domain
 108 socket's buffer. It will not take effect unless PF_UNIX flag is specified.
 109
 110
 111 3. /proc/sys/net/ipv4 - IPV4 settings
 112 -------------------------------------------------------
 113 Please see: Documentation/networking/ip-sysctl.txt and ipvs-sysctl.txt for
 114 descriptions of these entries.
 115
 116
 117 4. Appletalk
 118 -------------------------------------------------------
 119
 120 The /proc/sys/net/appletalk  directory  holds the Appletalk configuration data
 121 when Appletalk is loaded. The configurable parameters are:
 122
 123 aarp-expiry-time
 124 ----------------
 125
 126 The amount  of  time  we keep an ARP entry before expiring it. Used to age out
 127 old hosts.
 128
 129 aarp-resolve-time
 130 -----------------
 131
 132 The amount of time we will spend trying to resolve an Appletalk address.
 133
 134 aarp-retransmit-limit
 135 ---------------------
 136
 137 The number of times we will retransmit a query before giving up.
 138
 139 aarp-tick-time
 140 --------------
 141
 142 Controls the rate at which expires are checked.
 143
 144 The directory  /proc/net/appletalk  holds the list of active Appletalk sockets
 145 on a machine.
 146
 147 The fields  indicate  the DDP type, the local address (in network:node format)
 148 the remote  address,  the  size of the transmit pending queue, the size of the
 149 received queue  (bytes waiting for applications to read) the state and the uid
 150 owning the socket.
 151
 152 /proc/net/atalk_iface lists  all  the  interfaces  configured for appletalk.It
 153 shows the  name  of the interface, its Appletalk address, the network range on
 154 that address  (or  network number for phase 1 networks), and the status of the
 155 interface.
 156
 157 /proc/net/atalk_route lists  each  known  network  route.  It lists the target
 158 (network) that the route leads to, the router (may be directly connected), the
 159 route flags, and the device the route is using.
 160
 161
 162 5. IPX
 163 -------------------------------------------------------
 164
 165 The IPX protocol has no tunable values in proc/sys/net.
 166
 167 The IPX  protocol  does,  however,  provide  proc/net/ipx. This lists each IPX
 168 socket giving  the  local  and  remote  addresses  in  Novell  format (that is
 169 network:node:port). In  accordance  with  the  strange  Novell  tradition,
 170 everything but the port is in hex. Not_Connected is displayed for sockets that
 171 are not  tied to a specific remote address. The Tx and Rx queue sizes indicate
 172 the number  of  bytes  pending  for  transmission  and  reception.  The  state
 173 indicates the  state  the  socket  is  in and the uid is the owning uid of the
 174 socket.
 175
 176 The /proc/net/ipx_interface  file lists all IPX interfaces. For each interface
 177 it gives  the network number, the node number, and indicates if the network is
 178 the primary  network.  It  also  indicates  which  device  it  is bound to (or
 179 Internal for  internal  networks)  and  the  Frame  Type if appropriate. Linux
 180 supports 802.3,  802.2,  802.2  SNAP  and DIX (Blue Book) ethernet framing for
 181 IPX.
 182
 183 The /proc/net/ipx_route  table  holds  a list of IPX routes. For each route it
 184 gives the  destination  network, the router node (or Directly) and the network
 185 address of the router (or Connected) for internal networks.