3 ss \- another utility to investigate sockets
6 .RI [ options ] " [ FILTER ]"
9 is used to dump socket statistics. It allows showing information similar
12 It can display more TCP and state information than other tools.
15 When no option is used ss displays a list of open non-listening
16 sockets (e.g. TCP/UNIX/UDP) that have established connection.
19 Show summary of options.
22 Output version information.
28 Print each socket's data on a single line.
31 Do not try to resolve service names.
34 Try to resolve numeric address/ports.
37 Display both listening and non-listening (for TCP this means
38 established connections) sockets.
41 Display only listening sockets (these are omitted by default).
44 Show timer information. For TCP protocol, the output format is:
47 timer:(<timer_name>,<expire_time>,<retrans>)
51 the name of the timer, there are five kind of timer names:
55 : means one of these timers: TCP retrans timer, TCP early retrans
56 timer and tail loss probe timer
58 .BR keepalive ": tcp keep alive timer"
60 .BR timewait ": timewait stage timer"
62 .BR persist ": zero window probe timer"
64 .BR unknown ": none of the above timers"
68 how long time the timer will expire
72 how many times the retransmission occured
76 Show detailed socket information. The output format is:
79 uid:<uid_number> ino:<inode_number> sk:<cookie>
83 the user id the socket belongs to
87 the socket's inode number in VFS
95 Show socket memory usage. The output format is:
98 skmem:(r<rmem_alloc>,rb<rcv_buf>,t<wmem_alloc>,tb<snd_buf>,
102 f<fwd_alloc>,w<wmem_queued>,
108 o<opt_mem>,bl<back_log>)
114 the memory allocated for receiving packet
118 the total memory can be allocated for receiving packet
122 the memory used for sending packet (which has been sent to layer 3)
126 the total memory can be allocated for sending packet
130 the memory allocated by the socket as cache, but not used for
131 receiving/sending packet yet. If need memory to send/receive packet,
132 the memory in this cache will be used before allocate additional
137 The memory allocated for sending packet (which has not been sent to layer 3)
141 The memory used for storing socket option, e.g., the key for TCP MD5 signature
145 The memory used for the sk backlog queue. On a process context, if the
146 process is receiving packet, and a new packet is received, it will be
147 put into the sk backlog queue, so it can be received by the process
151 .B \-p, \-\-processes
152 Show process using socket.
155 Show internal TCP information. Below fields may appear:
160 show string "ts" if the timestamp option is set
164 show string "sack" if the sack option is set
168 show string "ecn" if the explicit congestion notification option is set
172 show string "ecnseen" if the saw ecn flag is found in received packets
176 show string "fastopen" if the fastopen option is set
180 the congestion algorithm name, the default congestion algorithm is "cubic"
183 .B wscale:<snd_wscale>:<rcv_wscale>
184 if window scale option is used, this field shows the send scale factor
185 and receive scale factor
189 tcp re-transmission timeout value, the unit is millisecond
192 .B backoff:<icsk_backoff>
193 used for exponential backoff re-transmission, the actual
194 re-transmission timeout value is icsk_rto << icsk_backoff
197 .B rtt:<rtt>/<rttvar>
198 rtt is the average round trip time, rttvar is the mean deviation of
199 rtt, their units are millisecond
203 ack timeout, unit is millisecond, used for delay ack mode
211 congestion window size
218 .B ssthresh:<ssthresh>
219 tcp congestion window slow start threshold
222 .B bytes_acked:<bytes_acked>
226 .B bytes_received:<bytes_received>
230 .B segs_out:<segs_out>
238 .B send <send_bps>bps
243 how long time since the last packet sent, the unit is millisecond
247 how long time since the last packet received, the unit is millisecond
251 how long time since the last ack received, the unit is millisecond
254 .B pacing_rate <pacing_rate>bps/<max_pacing_rate>bps
255 the pacing rate and max pacing rate
258 .B rcv_space:<rcv_space>
259 a helper variable for TCP internal auto tuning socket receive buffer
263 Show ToS and priority information. Below fields may appear:
268 IPv4 Type-of-Service byte
272 IPv6 Traffic Class byte
276 Class id set by net_cls cgroup. If class is zero this shows priority
281 Attempts to forcibly close sockets. This option displays sockets that are
282 successfully closed and silently skips sockets that the kernel does not support
283 closing. It supports IPv4 and IPv6 sockets only.
286 Print summary statistics. This option does not parse socket lists obtaining
287 summary from various sources. It is useful when amount of sockets is so huge
288 that parsing /proc/net/tcp is painful.
291 Continually display sockets as they are destroyed
296 option but also shows process security context.
300 sockets the initiating process context is displayed as follows:
304 If valid pid show the process context.
306 If destination is kernel (pid = 0) show kernel initial context.
308 If a unique identifier has been allocated by the kernel or netlink user,
309 show context as "unavailable". This will generally indicate that a
310 process has more than one netlink socket active.
317 option but also shows the socket context. The socket context is
318 taken from the associated inode and is not the actual socket
319 context held by the kernel. Sockets are typically labeled with the
320 context of the creating process, however the context shown will reflect
321 any policy role, type and/or range transition rules applied,
322 and is therefore a useful reference.
324 .B \-N NSNAME, \-\-net=NSNAME
325 Switch to the specified network namespace name.
328 Show socket BPF filters (only administrators are allowed to get these
332 Display only IP version 4 sockets (alias for -f inet).
335 Display only IP version 6 sockets (alias for -f inet6).
338 Display PACKET sockets (alias for -f link).
347 Display DCCP sockets.
353 Display Unix domain sockets (alias for -f unix).
356 Display SCTP sockets.
359 Display vsock sockets (alias for -f vsock).
362 Display XDP sockets (alias for -f xdp).
364 .B \-f FAMILY, \-\-family=FAMILY
365 Display sockets of type FAMILY. Currently the following families are
366 supported: unix, inet, inet6, link, netlink, vsock, xdp.
368 .B \-A QUERY, \-\-query=QUERY, \-\-socket=QUERY
369 List of socket tables to dump, separated by commas. The following identifiers
370 are understood: all, inet, tcp, udp, raw, unix, packet, netlink, unix_dgram,
371 unix_stream, unix_seqpacket, packet_raw, packet_dgram, dccp, sctp,
372 vsock_stream, vsock_dgram, xdp Any item in the list may optionally be
373 prefixed by an exclamation mark
375 to exclude that socket table from being dumped.
377 .B \-D FILE, \-\-diag=FILE
378 Do not display anything, just dump raw information about TCP sockets
379 to FILE after applying filters. If FILE is - stdout is used.
381 .B \-F FILE, \-\-filter=FILE
382 Read filter information from FILE. Each line of FILE is interpreted
383 like single command line option. If FILE is - stdin is used.
385 .B FILTER := [ state STATE-FILTER ] [ EXPRESSION ]
386 Please take a look at the official documentation for details regarding filters.
391 allows to construct arbitrary set of states to match. Its syntax is
392 sequence of keywords state and exclude followed by identifier of
395 Available identifiers are:
397 All standard TCP states:
398 .BR established ", " syn-sent ", " syn-recv ", " fin-wait-1 ", " fin-wait-2 ", " time-wait ", " closed ", " close-wait ", " last-ack ", "
399 .BR listening " and " closing.
405 - all the states except for
406 .BR listening " and " closed
415 - states, which are maintained as minisockets, i.e.
416 .BR time-wait " and " syn-recv
425 Display all TCP sockets.
428 Display all TCP sockets with process SELinux security contexts.
431 Display all UDP sockets.
433 .B ss -o state established '( dport = :ssh or sport = :ssh )'
434 Display all established ssh connections.
436 .B ss -x src /tmp/.X11-unix/*
437 Find all local processes connected to X server.
439 .B ss -o state fin-wait-1 '( sport = :http or sport = :https )' dst 193.233.7/24
440 List all the tcp sockets in state FIN-WAIT-1 for our apache to network
441 193.233.7/24 and look at their timers.
443 .B ss -a -A 'all,!tcp'
444 List sockets in all states from all socket tables but TCP.
449 - https://tools.ietf.org/rfc/rfc793.txt (TCP states)
453 was written by Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>.
455 This manual page was written by Michael Prokop <mika@grml.org>
456 for the Debian project (but may be used by others).