Provided by: iproute2_5.5.0-1ubuntu1_amd64 bug


       ss - another utility to investigate sockets


       ss [options] [ FILTER ]


       ss  is  used  to dump socket statistics. It allows showing information similar to netstat.
       It can display more TCP and state information than other tools.


       When  no  option  is  used  ss  displays  a  list  of  open  non-listening  sockets  (e.g.
       TCP/UNIX/UDP) that have established connection.

       -h, --help
              Show summary of options.

       -V, --version
              Output version information.

       -H, --no-header
              Suppress header line.

       -O, --oneline
              Print each socket's data on a single line.

       -n, --numeric
              Do not try to resolve service names. Show exact bandwidth values, instead of human-

       -r, --resolve
              Try to resolve numeric address/ports.

       -a, --all
              Display  both  listening  and  non-listening  (for  TCP  this   means   established
              connections) sockets.

       -l, --listening
              Display only listening sockets (these are omitted by default).

       -o, --options
              Show timer information. For TCP protocol, the output format is:


                     the name of the timer, there are five kind of timer names:

                     on  :  means one of these timers: TCP retrans timer, TCP early retrans timer
                     and tail loss probe timer

                     keepalive: tcp keep alive timer

                     timewait: timewait stage timer

                     persist: zero window probe timer

                     unknown: none of the above timers

                     how long time the timer will expire

                     how many times the retransmission occured

       -e, --extended
              Show detailed socket information. The output format is:

              uid:<uid_number> ino:<inode_number> sk:<cookie>

                     the user id the socket belongs to

                     the socket's inode number in VFS

                     an uuid of the socket

       -m, --memory
              Show socket memory usage. The output format is:


                     the memory allocated for receiving packet

                     the total memory can be allocated for receiving packet

                     the memory used for sending packet (which has been sent to layer 3)

                     the total memory can be allocated for sending packet

                     the  memory  allocated  by  the  socket  as  cache,   but   not   used   for
                     receiving/sending  packet  yet.  If  need memory to send/receive packet, the
                     memory in this cache will be used before allocate additional memory.

                     The memory allocated for sending packet (which has not been sent to layer 3)

                     The memory used for storing  socket  option,  e.g.,  the  key  for  TCP  MD5

                     The  memory  used  for  the  sk  backlog queue. On a process context, if the
                     process is receiving packet, and a new packet is received, it  will  be  put
                     into the sk backlog queue, so it can be received by the process immediately

                     the number of packets dropped before they are de-multiplexed into the socket

       -p, --processes
              Show process using socket.

       -i, --info
              Show internal TCP information. Below fields may appear:

              ts     show string "ts" if the timestamp option is set

              sack   show string "sack" if the sack option is set

              ecn    show string "ecn" if the explicit congestion notification option is set

                     show string "ecnseen" if the saw ecn flag is found in received packets

                     show string "fastopen" if the fastopen option is set

                     the congestion algorithm name, the default congestion algorithm is "cubic"

                     if  window  scale option is used, this field shows the send scale factor and
                     receive scale factor

                     tcp re-transmission timeout value, the unit is millisecond

                     used for exponential backoff  re-transmission,  the  actual  re-transmission
                     timeout value is icsk_rto << icsk_backoff

                     rtt  is  the  average  round trip time, rttvar is the mean deviation of rtt,
                     their units are millisecond

                     ack timeout, unit is millisecond, used for delay ack mode

                     max segment size

                     congestion window size

                     path MTU value

                     tcp congestion window slow start threshold

                     bytes acked

                     bytes received

                     segments sent out

                     segments received

              send <send_bps>bps
                     egress bps

                     how long time since the last packet sent, the unit is millisecond

                     how long time since the last packet received, the unit is millisecond

                     how long time since the last ack received, the unit is millisecond

              pacing_rate <pacing_rate>bps/<max_pacing_rate>bps
                     the pacing rate and max pacing rate

                     a helper variable for TCP internal auto tuning socket receive buffer

       --tos  Show ToS and priority information. Below fields may appear:

              tos    IPv4 Type-of-Service byte

              tclass IPv6 Traffic Class byte

                     Class id set by net_cls cgroup. If class is zero this shows priority set  by

       -K, --kill
              Attempts  to  forcibly  close  sockets.  This  option  displays  sockets  that  are
              successfully closed and silently skips sockets that the  kernel  does  not  support
              closing. It supports IPv4 and IPv6 sockets only.

       -s, --summary
              Print summary statistics. This option does not parse socket lists obtaining summary
              from various sources. It is useful when amount of sockets is so huge  that  parsing
              /proc/net/tcp is painful.

       -E, --events
              Continually display sockets as they are destroyed

       -Z, --context
              As the -p option but also shows process security context.

              For netlink(7) sockets the initiating process context is displayed as follows:

                     1.  If valid pid show the process context.

                     2.  If destination is kernel (pid = 0) show kernel initial context.

                     3.  If a unique identifier has been allocated by the kernel or netlink user,
                         show context as "unavailable".  This  will  generally  indicate  that  a
                         process has more than one netlink socket active.

       -z, --contexts
              As  the  -Z  option  but also shows the socket context. The socket context is taken
              from the associated inode and is not the actual socket context held by the  kernel.
              Sockets are typically labeled with the context of the creating process, however the
              context shown will reflect any policy role,  type  and/or  range  transition  rules
              applied, and is therefore a useful reference.

       -N NSNAME, --net=NSNAME
              Switch to the specified network namespace name.

       -b, --bpf
              Show socket BPF filters (only administrators are allowed to get these information).

       -4, --ipv4
              Display only IP version 4 sockets (alias for -f inet).

       -6, --ipv6
              Display only IP version 6 sockets (alias for -f inet6).

       -0, --packet
              Display PACKET sockets (alias for -f link).

       -t, --tcp
              Display TCP sockets.

       -u, --udp
              Display UDP sockets.

       -d, --dccp
              Display DCCP sockets.

       -w, --raw
              Display RAW sockets.

       -x, --unix
              Display Unix domain sockets (alias for -f unix).

       -S, --sctp
              Display SCTP sockets.

              Display vsock sockets (alias for -f vsock).

       --xdp  Display XDP sockets (alias for -f xdp).

       -f FAMILY, --family=FAMILY
              Display  sockets  of  type FAMILY.  Currently the following families are supported:
              unix, inet, inet6, link, netlink, vsock, xdp.

       -A QUERY, --query=QUERY, --socket=QUERY
              List of socket tables to dump, separated by commas. The following  identifiers  are
              understood:   all,   inet,  tcp,  udp,  raw,  unix,  packet,  netlink,  unix_dgram,
              unix_stream, unix_seqpacket, packet_raw, packet_dgram,  dccp,  sctp,  vsock_stream,
              vsock_dgram,  xdp Any item in the list may optionally be prefixed by an exclamation
              mark (!)  to exclude that socket table from being dumped.

       -D FILE, --diag=FILE
              Do not display anything, just dump raw information about TCP sockets to FILE  after
              applying filters. If FILE is - stdout is used.

       -F FILE, --filter=FILE
              Read  filter  information  from FILE.  Each line of FILE is interpreted like single
              command line option. If FILE is - stdin is used.

       FILTER := [ state STATE-FILTER ] [ EXPRESSION ]
              Please take a look at the official documentation for details regarding filters.


       STATE-FILTER allows to construct arbitrary set of states to match. Its syntax is  sequence
       of keywords state and exclude followed by identifier of state.

       Available identifiers are:

              All  standard  TCP states: established, syn-sent, syn-recv, fin-wait-1, fin-wait-2,
              time-wait, closed, close-wait, last-ack, listening and closing.

              all - for all the states

              connected - all the states except for listening and closed

              synchronized - all the connected states except for syn-sent

              bucket - states, which are maintained as minisockets, i.e.  time-wait and syn-recv

              big - opposite to bucket


       ss -t -a
              Display all TCP sockets.

       ss -t -a -Z
              Display all TCP sockets with process SELinux security contexts.

       ss -u -a
              Display all UDP sockets.

       ss -o state established '( dport = :ssh or sport = :ssh )'
              Display all established ssh connections.

       ss -x src /tmp/.X11-unix/*
              Find all local processes connected to X server.

       ss -o state fin-wait-1 '( sport = :http or sport = :https )' dst 193.233.7/24
              List all the tcp sockets in state FIN-WAIT-1 for our apache to network 193.233.7/24
              and look at their timers.

       ss -a -A 'all,!tcp'
              List sockets in all states from all socket tables but TCP.


       RFC 793 - (TCP states)


       ss was written by Alexey Kuznetsov, <>.

       This manual page was written by Michael Prokop <> for the Debian project (but
       may be used by others).