Root/Documentation/sysctl/net.txt

1Documentation 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
7For general info and legal blurb, please look in README.
8
9==============================================================
10
11This 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
14The interface to the networking parts of the kernel is located in
15/proc/sys/net. The following table shows all possible subdirectories.You may
16see only some of them, depending on your kernel's configuration.
17
18
19Table : 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
321. /proc/sys/net/core - Network core options
33-------------------------------------------------------
34
35rmem_default
36------------
37
38The default setting of the socket receive buffer in bytes.
39
40rmem_max
41--------
42
43The maximum receive socket buffer size in bytes.
44
45wmem_default
46------------
47
48The default setting (in bytes) of the socket send buffer.
49
50wmem_max
51--------
52
53The maximum send socket buffer size in bytes.
54
55message_burst and message_cost
56------------------------------
57
58These parameters are used to limit the warning messages written to the kernel
59log from the networking code. They enforce a rate limit to make a
60denial-of-service attack impossible. A higher message_cost factor, results in
61fewer messages that will be written. Message_burst controls when messages will
62be dropped. The default settings limit warning messages to one every five
63seconds.
64
65warnings
66--------
67
68This controls console messages from the networking stack that can occur because
69of problems on the network like duplicate address or bad checksums. Normally,
70this should be enabled, but if the problem persists the messages can be
71disabled.
72
73netdev_budget
74-------------
75
76Maximum number of packets taken from all interfaces in one polling cycle (NAPI
77poll). In one polling cycle interfaces which are registered to polling are
78probed in a round-robin manner. The limit of packets in one such probe can be
79set per-device via sysfs class/net/<device>/weight .
80
81netdev_max_backlog
82------------------
83
84Maximum number of packets, queued on the INPUT side, when the interface
85receives packets faster than kernel can process them.
86
87optmem_max
88----------
89
90Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence
91of struct cmsghdr structures with appended data.
92
932. /proc/sys/net/unix - Parameters for Unix domain sockets
94-------------------------------------------------------
95
96There is only one file in this directory.
97unix_dgram_qlen limits the max number of datagrams queued in Unix domain
98socket's buffer. It will not take effect unless PF_UNIX flag is specified.
99
100
1013. /proc/sys/net/ipv4 - IPV4 settings
102-------------------------------------------------------
103Please see: Documentation/networking/ip-sysctl.txt and ipvs-sysctl.txt for
104descriptions of these entries.
105
106
1074. Appletalk
108-------------------------------------------------------
109
110The /proc/sys/net/appletalk directory holds the Appletalk configuration data
111when Appletalk is loaded. The configurable parameters are:
112
113aarp-expiry-time
114----------------
115
116The amount of time we keep an ARP entry before expiring it. Used to age out
117old hosts.
118
119aarp-resolve-time
120-----------------
121
122The amount of time we will spend trying to resolve an Appletalk address.
123
124aarp-retransmit-limit
125---------------------
126
127The number of times we will retransmit a query before giving up.
128
129aarp-tick-time
130--------------
131
132Controls the rate at which expires are checked.
133
134The directory /proc/net/appletalk holds the list of active Appletalk sockets
135on a machine.
136
137The fields indicate the DDP type, the local address (in network:node format)
138the remote address, the size of the transmit pending queue, the size of the
139received queue (bytes waiting for applications to read) the state and the uid
140owning the socket.
141
142/proc/net/atalk_iface lists all the interfaces configured for appletalk.It
143shows the name of the interface, its Appletalk address, the network range on
144that address (or network number for phase 1 networks), and the status of the
145interface.
146
147/proc/net/atalk_route lists each known network route. It lists the target
148(network) that the route leads to, the router (may be directly connected), the
149route flags, and the device the route is using.
150
151
1525. IPX
153-------------------------------------------------------
154
155The IPX protocol has no tunable values in proc/sys/net.
156
157The IPX protocol does, however, provide proc/net/ipx. This lists each IPX
158socket giving the local and remote addresses in Novell format (that is
159network:node:port). In accordance with the strange Novell tradition,
160everything but the port is in hex. Not_Connected is displayed for sockets that
161are not tied to a specific remote address. The Tx and Rx queue sizes indicate
162the number of bytes pending for transmission and reception. The state
163indicates the state the socket is in and the uid is the owning uid of the
164socket.
165
166The /proc/net/ipx_interface file lists all IPX interfaces. For each interface
167it gives the network number, the node number, and indicates if the network is
168the primary network. It also indicates which device it is bound to (or
169Internal for internal networks) and the Frame Type if appropriate. Linux
170supports 802.3, 802.2, 802.2 SNAP and DIX (Blue Book) ethernet framing for
171IPX.
172
173The /proc/net/ipx_route table holds a list of IPX routes. For each route it
174gives the destination network, the router node (or Directly) and the network
175address of the router (or Connected) for internal networks.
176

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