About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / sysctl / net.txt




Custom Search

Based on kernel version 3.16. Page generated on 2014-08-06 21:41 EST.

1	Documentation for /proc/sys/net/*
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
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        tipc       TIPC
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	default_qdisc
54	--------------
55	
56	The default queuing discipline to use for network devices. This allows
57	overriding the default queue discipline of pfifo_fast with an
58	alternative. Since the default queuing discipline is created with the
59	no additional parameters so is best suited to queuing disciplines that
60	work well without configuration like stochastic fair queue (sfq),
61	CoDel (codel) or fair queue CoDel (fq_codel). Don't use queuing disciplines
62	like Hierarchical Token Bucket or Deficit Round Robin which require setting
63	up classes and bandwidths.
64	Default: pfifo_fast
65	
66	busy_read
67	----------------
68	Low latency busy poll timeout for socket reads. (needs CONFIG_NET_RX_BUSY_POLL)
69	Approximate time in us to busy loop waiting for packets on the device queue.
70	This sets the default value of the SO_BUSY_POLL socket option.
71	Can be set or overridden per socket by setting socket option SO_BUSY_POLL,
72	which is the preferred method of enabling. If you need to enable the feature
73	globally via sysctl, a value of 50 is recommended.
74	Will increase power usage.
75	Default: 0 (off)
76	
77	busy_poll
78	----------------
79	Low latency busy poll timeout for poll and select. (needs CONFIG_NET_RX_BUSY_POLL)
80	Approximate time in us to busy loop waiting for events.
81	Recommended value depends on the number of sockets you poll on.
82	For several sockets 50, for several hundreds 100.
83	For more than that you probably want to use epoll.
84	Note that only sockets with SO_BUSY_POLL set will be busy polled,
85	so you want to either selectively set SO_BUSY_POLL on those sockets or set
86	sysctl.net.busy_read globally.
87	Will increase power usage.
88	Default: 0 (off)
89	
90	rmem_default
91	------------
92	
93	The default setting of the socket receive buffer in bytes.
94	
95	rmem_max
96	--------
97	
98	The maximum receive socket buffer size in bytes.
99	
100	wmem_default
101	------------
102	
103	The default setting (in bytes) of the socket send buffer.
104	
105	wmem_max
106	--------
107	
108	The maximum send socket buffer size in bytes.
109	
110	message_burst and message_cost
111	------------------------------
112	
113	These parameters  are used to limit the warning messages written to the kernel
114	log from  the  networking  code.  They  enforce  a  rate  limit  to  make  a
115	denial-of-service attack  impossible. A higher message_cost factor, results in
116	fewer messages that will be written. Message_burst controls when messages will
117	be dropped.  The  default  settings  limit  warning messages to one every five
118	seconds.
119	
120	warnings
121	--------
122	
123	This controls console messages from the networking stack that can occur because
124	of problems on the network like duplicate address or bad checksums. Normally,
125	this should be enabled, but if the problem persists the messages can be
126	disabled.
127	
128	netdev_budget
129	-------------
130	
131	Maximum number of packets taken from all interfaces in one polling cycle (NAPI
132	poll). In one polling cycle interfaces which are registered to polling are
133	probed in a round-robin manner.
134	
135	netdev_max_backlog
136	------------------
137	
138	Maximum number  of  packets,  queued  on  the  INPUT  side, when the interface
139	receives packets faster than kernel can process them.
140	
141	netdev_tstamp_prequeue
142	----------------------
143	
144	If set to 0, RX packet timestamps can be sampled after RPS processing, when
145	the target CPU processes packets. It might give some delay on timestamps, but
146	permit to distribute the load on several cpus.
147	
148	If set to 1 (default), timestamps are sampled as soon as possible, before
149	queueing.
150	
151	optmem_max
152	----------
153	
154	Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence
155	of struct cmsghdr structures with appended data.
156	
157	2. /proc/sys/net/unix - Parameters for Unix domain sockets
158	-------------------------------------------------------
159	
160	There is only one file in this directory.
161	unix_dgram_qlen limits the max number of datagrams queued in Unix domain
162	socket's buffer. It will not take effect unless PF_UNIX flag is specified.
163	
164	
165	3. /proc/sys/net/ipv4 - IPV4 settings
166	-------------------------------------------------------
167	Please see: Documentation/networking/ip-sysctl.txt and ipvs-sysctl.txt for
168	descriptions of these entries.
169	
170	
171	4. Appletalk
172	-------------------------------------------------------
173	
174	The /proc/sys/net/appletalk  directory  holds the Appletalk configuration data
175	when Appletalk is loaded. The configurable parameters are:
176	
177	aarp-expiry-time
178	----------------
179	
180	The amount  of  time  we keep an ARP entry before expiring it. Used to age out
181	old hosts.
182	
183	aarp-resolve-time
184	-----------------
185	
186	The amount of time we will spend trying to resolve an Appletalk address.
187	
188	aarp-retransmit-limit
189	---------------------
190	
191	The number of times we will retransmit a query before giving up.
192	
193	aarp-tick-time
194	--------------
195	
196	Controls the rate at which expires are checked.
197	
198	The directory  /proc/net/appletalk  holds the list of active Appletalk sockets
199	on a machine.
200	
201	The fields  indicate  the DDP type, the local address (in network:node format)
202	the remote  address,  the  size of the transmit pending queue, the size of the
203	received queue  (bytes waiting for applications to read) the state and the uid
204	owning the socket.
205	
206	/proc/net/atalk_iface lists  all  the  interfaces  configured for appletalk.It
207	shows the  name  of the interface, its Appletalk address, the network range on
208	that address  (or  network number for phase 1 networks), and the status of the
209	interface.
210	
211	/proc/net/atalk_route lists  each  known  network  route.  It lists the target
212	(network) that the route leads to, the router (may be directly connected), the
213	route flags, and the device the route is using.
214	
215	
216	5. IPX
217	-------------------------------------------------------
218	
219	The IPX protocol has no tunable values in proc/sys/net.
220	
221	The IPX  protocol  does,  however,  provide  proc/net/ipx. This lists each IPX
222	socket giving  the  local  and  remote  addresses  in  Novell  format (that is
223	network:node:port). In  accordance  with  the  strange  Novell  tradition,
224	everything but the port is in hex. Not_Connected is displayed for sockets that
225	are not  tied to a specific remote address. The Tx and Rx queue sizes indicate
226	the number  of  bytes  pending  for  transmission  and  reception.  The  state
227	indicates the  state  the  socket  is  in and the uid is the owning uid of the
228	socket.
229	
230	The /proc/net/ipx_interface  file lists all IPX interfaces. For each interface
231	it gives  the network number, the node number, and indicates if the network is
232	the primary  network.  It  also  indicates  which  device  it  is bound to (or
233	Internal for  internal  networks)  and  the  Frame  Type if appropriate. Linux
234	supports 802.3,  802.2,  802.2  SNAP  and DIX (Blue Book) ethernet framing for
235	IPX.
236	
237	The /proc/net/ipx_route  table  holds  a list of IPX routes. For each route it
238	gives the  destination  network, the router node (or Directly) and the network
239	address of the router (or Connected) for internal networks.
240	
241	6. TIPC
242	-------------------------------------------------------
243	
244	The TIPC protocol now has a tunable for the receive memory, similar to the
245	tcp_rmem - i.e. a vector of 3 INTEGERs: (min, default, max)
246	
247	    # cat /proc/sys/net/tipc/tipc_rmem
248	    4252725 34021800        68043600
249	    #
250	
251	The max value is set to CONN_OVERLOAD_LIMIT, and the default and min values
252	are scaled (shifted) versions of that same value.  Note that the min value
253	is not at this point in time used in any meaningful way, but the triplet is
254	preserved in order to be consistent with things like tcp_rmem.
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.