1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
|
Documentation for /proc/sys/net/*
(c) 1999 Terrehon Bowden <terrehon@pacbell.net>
Bodo Bauer <bb@ricochet.net>
(c) 2000 Jorge Nerin <comandante@zaralinux.com>
(c) 2009 Shen Feng <shen@cn.fujitsu.com>
For general info and legal blurb, please look in README.
==============================================================
This file contains the documentation for the sysctl files in
/proc/sys/net
The interface to the networking parts of the kernel is located in
/proc/sys/net. The following table shows all possible subdirectories. You may
see only some of them, depending on your kernel's configuration.
Table : 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 tipc TIPC
..............................................................................
1. /proc/sys/net/core - Network core options
-------------------------------------------------------
bpf_jit_enable
--------------
This enables Berkeley Packet Filter Just in Time compiler.
Currently supported on x86_64 architecture, bpf_jit provides a framework
to speed packet filtering, the one used by tcpdump/libpcap for example.
Values :
0 - disable the JIT (default value)
1 - enable the JIT
2 - enable the JIT and ask the compiler to emit traces on kernel log.
dev_weight
--------------
The maximum number of packets that kernel can handle on a NAPI interrupt,
it's a Per-CPU variable.
Default: 64
default_qdisc
--------------
The default queuing discipline to use for network devices. This allows
overriding the default queue discipline of pfifo_fast with an
alternative. Since the default queuing discipline is created with the
no additional parameters so is best suited to queuing disciplines that
work well without configuration like stochastic fair queue (sfq),
CoDel (codel) or fair queue CoDel (fq_codel). Don't use queuing disciplines
like Hierarchical Token Bucket or Deficit Round Robin which require setting
up classes and bandwidths.
Default: pfifo_fast
busy_read
----------------
Low latency busy poll timeout for socket reads. (needs CONFIG_NET_RX_BUSY_POLL)
Approximate time in us to busy loop waiting for packets on the device queue.
This sets the default value of the SO_BUSY_POLL socket option.
Can be set or overridden per socket by setting socket option SO_BUSY_POLL,
which is the preferred method of enabling. If you need to enable the feature
globally via sysctl, a value of 50 is recommended.
Will increase power usage.
Default: 0 (off)
busy_poll
----------------
Low latency busy poll timeout for poll and select. (needs CONFIG_NET_RX_BUSY_POLL)
Approximate time in us to busy loop waiting for events.
Recommended value depends on the number of sockets you poll on.
For several sockets 50, for several hundreds 100.
For more than that you probably want to use epoll.
Note that only sockets with SO_BUSY_POLL set will be busy polled,
so you want to either selectively set SO_BUSY_POLL on those sockets or set
sysctl.net.busy_read globally.
Will increase power usage.
Default: 0 (off)
rmem_default
------------
The default setting of the socket receive buffer in bytes.
rmem_max
--------
The maximum receive socket buffer size in bytes.
wmem_default
------------
The default setting (in bytes) of the socket send buffer.
wmem_max
--------
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. 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.
warnings
--------
This controls console messages from the networking stack that can occur because
of problems on the network like duplicate address or bad checksums. Normally,
this should be enabled, but if the problem persists the messages can be
disabled.
netdev_budget
-------------
Maximum number of packets taken from all interfaces in one polling cycle (NAPI
poll). In one polling cycle interfaces which are registered to polling are
probed in a round-robin manner.
netdev_max_backlog
------------------
Maximum number of packets, queued on the INPUT side, when the interface
receives packets faster than kernel can process them.
netdev_tstamp_prequeue
----------------------
If set to 0, RX packet timestamps can be sampled after RPS processing, when
the target CPU processes packets. It might give some delay on timestamps, but
permit to distribute the load on several cpus.
If set to 1 (default), timestamps are sampled as soon as possible, before
queueing.
optmem_max
----------
Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence
of struct cmsghdr structures with appended data.
2. /proc/sys/net/unix - Parameters for Unix domain sockets
-------------------------------------------------------
There is only one file in this directory.
unix_dgram_qlen limits the max number of datagrams queued in Unix domain
socket's buffer. It will not take effect unless PF_UNIX flag is specified.
3. /proc/sys/net/ipv4 - IPV4 settings
-------------------------------------------------------
Please see: Documentation/networking/ip-sysctl.txt and ipvs-sysctl.txt for
descriptions of these entries.
4. 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 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.
aarp-retransmit-limit
---------------------
The number of times we will retransmit a query before giving up.
aarp-tick-time
--------------
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.
5. 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.
6. TIPC
-------------------------------------------------------
The TIPC protocol now has a tunable for the receive memory, similar to the
tcp_rmem - i.e. a vector of 3 INTEGERs: (min, default, max)
# cat /proc/sys/net/tipc/tipc_rmem
4252725 34021800 68043600
#
The max value is set to CONN_OVERLOAD_LIMIT, and the default and min values
are scaled (shifted) versions of that same value. Note that the min value
is not at this point in time used in any meaningful way, but the triplet is
preserved in order to be consistent with things like tcp_rmem.
|
