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 bpf_jit_enable
  36 --------------
  37
  38 This enables Berkeley Packet Filter Just in Time compiler.
  39 Currently supported on x86_64 architecture, bpf_jit provides a framework
  40 to speed packet filtering, the one used by tcpdump/libpcap for example.
  41 Values :
  42         0 - disable the JIT (default value)
  43         1 - enable the JIT
  44         2 - enable the JIT and ask the compiler to emit traces on kernel log.
  45
  46 dev_weight
  47 --------------
  48
  49 The maximum number of packets that kernel can handle on a NAPI interrupt,
  50 it's a Per-CPU variable.
  51 Default: 64
  52
  53 rmem_default
  54 ------------
  55
  56 The default setting of the socket receive buffer in bytes.
  57
  58 rmem_max
  59 --------
  60
  61 The maximum receive socket buffer size in bytes.
  62
  63 wmem_default
  64 ------------
  65
  66 The default setting (in bytes) of the socket send buffer.
  67
  68 wmem_max
  69 --------
  70
  71 The maximum send socket buffer size in bytes.
  72
  73 message_burst and message_cost
  74 ------------------------------
  75
  76 These parameters  are used to limit the warning messages written to the kernel
  77 log from  the  networking  code.  They  enforce  a  rate  limit  to  make  a
  78 denial-of-service attack  impossible. A higher message_cost factor, results in
  79 fewer messages that will be written. Message_burst controls when messages will
  80 be dropped.  The  default  settings  limit  warning messages to one every five
  81 seconds.
  82
  83 warnings
  84 --------
  85
  86 This controls console messages from the networking stack that can occur because
  87 of problems on the network like duplicate address or bad checksums. Normally,
  88 this should be enabled, but if the problem persists the messages can be
  89 disabled.
  90
  91 netdev_budget
  92 -------------
  93
  94 Maximum number of packets taken from all interfaces in one polling cycle (NAPI
  95 poll). In one polling cycle interfaces which are registered to polling are
  96 probed in a round-robin manner. The limit of packets in one such probe can be
  97 set per-device via sysfs class/net/<device>/weight .
  98
  99 netdev_max_backlog
 100 ------------------
 101
 102 Maximum number  of  packets,  queued  on  the  INPUT  side, when the interface
 103 receives packets faster than kernel can process them.
 104
 105 netdev_tstamp_prequeue
 106 ----------------------
 107
 108 If set to 0, RX packet timestamps can be sampled after RPS processing, when
 109 the target CPU processes packets. It might give some delay on timestamps, but
 110 permit to distribute the load on several cpus.
 111
 112 If set to 1 (default), timestamps are sampled as soon as possible, before
 113 queueing.
 114
 115 optmem_max
 116 ----------
 117
 118 Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence
 119 of struct cmsghdr structures with appended data.
 120
 121 2. /proc/sys/net/unix - Parameters for Unix domain sockets
 122 -------------------------------------------------------
 123
 124 There is only one file in this directory.
 125 unix_dgram_qlen limits the max number of datagrams queued in Unix domain
 126 socket's buffer. It will not take effect unless PF_UNIX flag is specified.
 127
 128
 129 3. /proc/sys/net/ipv4 - IPV4 settings
 130 -------------------------------------------------------
 131 Please see: Documentation/networking/ip-sysctl.txt and ipvs-sysctl.txt for
 132 descriptions of these entries.
 133
 134
 135 4. Appletalk
 136 -------------------------------------------------------
 137
 138 The /proc/sys/net/appletalk  directory  holds the Appletalk configuration data
 139 when Appletalk is loaded. The configurable parameters are:
 140
 141 aarp-expiry-time
 142 ----------------
 143
 144 The amount  of  time  we keep an ARP entry before expiring it. Used to age out
 145 old hosts.
 146
 147 aarp-resolve-time
 148 -----------------
 149
 150 The amount of time we will spend trying to resolve an Appletalk address.
 151
 152 aarp-retransmit-limit
 153 ---------------------
 154
 155 The number of times we will retransmit a query before giving up.
 156
 157 aarp-tick-time
 158 --------------
 159
 160 Controls the rate at which expires are checked.
 161
 162 The directory  /proc/net/appletalk  holds the list of active Appletalk sockets
 163 on a machine.
 164
 165 The fields  indicate  the DDP type, the local address (in network:node format)
 166 the remote  address,  the  size of the transmit pending queue, the size of the
 167 received queue  (bytes waiting for applications to read) the state and the uid
 168 owning the socket.
 169
 170 /proc/net/atalk_iface lists  all  the  interfaces  configured for appletalk.It
 171 shows the  name  of the interface, its Appletalk address, the network range on
 172 that address  (or  network number for phase 1 networks), and the status of the
 173 interface.
 174
 175 /proc/net/atalk_route lists  each  known  network  route.  It lists the target
 176 (network) that the route leads to, the router (may be directly connected), the
 177 route flags, and the device the route is using.
 178
 179
 180 5. IPX
 181 -------------------------------------------------------
 182
 183 The IPX protocol has no tunable values in proc/sys/net.
 184
 185 The IPX  protocol  does,  however,  provide  proc/net/ipx. This lists each IPX
 186 socket giving  the  local  and  remote  addresses  in  Novell  format (that is
 187 network:node:port). In  accordance  with  the  strange  Novell  tradition,
 188 everything but the port is in hex. Not_Connected is displayed for sockets that
 189 are not  tied to a specific remote address. The Tx and Rx queue sizes indicate
 190 the number  of  bytes  pending  for  transmission  and  reception.  The  state
 191 indicates the  state  the  socket  is  in and the uid is the owning uid of the
 192 socket.
 193
 194 The /proc/net/ipx_interface  file lists all IPX interfaces. For each interface
 195 it gives  the network number, the node number, and indicates if the network is
 196 the primary  network.  It  also  indicates  which  device  it  is bound to (or
 197 Internal for  internal  networks)  and  the  Frame  Type if appropriate. Linux
 198 supports 802.3,  802.2,  802.2  SNAP  and DIX (Blue Book) ethernet framing for
 199 IPX.
 200
 201 The /proc/net/ipx_route  table  holds  a list of IPX routes. For each route it
 202 gives the  destination  network, the router node (or Directly) and the network
 203 address of the router (or Connected) for internal networks.