Provided by: iproute2_4.18.0-1ubuntu2_amd64 bug

NAME

       ss - another utility to investigate sockets

SYNOPSIS

       ss [options] [ FILTER ]

DESCRIPTION

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

OPTIONS

       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.

       -n, --numeric
              Do not try to resolve service names.

       -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:

              timer:(<timer_name>,<expire_time>,<retrans>)

              <timer_name>
                     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

              <expire_time>
                     how long time the timer will expire

              <retrans>
                     how many times the retran occurs

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

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

              <uid_number>
                     the user id the socket belongs to

              <inode_number>
                     the socket's inode number in VFS

              <cookie>
                     an uuid of the socket

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

              skmem:(r<rmem_alloc>,rb<rcv_buf>,t<wmem_alloc>,tb<snd_buf>,f<fwd_alloc>,w<wmem_queued>,o<opt_mem>,bl<back_log>)

              <rmem_alloc>
                     the memory allocated for receiving packet

              <rcv_buf>
                     the total memory can be allocated for receiving packet

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

              <snd_buf>
                     the total memory can be allocated for sending packet

              <fwd_alloc>
                     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.

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

              <opt_mem>
                     The memory used for storing  socket  option,  e.g.,  the  key  for  TCP  MD5
                     signature

              <back_log>
                     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

       -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

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

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

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

              wscale:<snd_wscale>:<rcv_wscale>
                     if  window scale option is used, this field shows the send scale factory and
                     receive scale factory

              rto:<icsk_rto>
                     tcp re-transmission timeout value, the unit is millisecond

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

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

              ato:<ato>
                     ack timeout, unit is millisecond, used for delay ack mode

              mss:<mss>
                     max segment size

              cwnd:<cwnd>
                     congestion window size

              pmtu:<pmtu>
                     path MTU value

              ssthresh:<ssthresh>
                     tcp congestion window slow start threshold

              bytes_acked:<bytes_acked>
                     bytes acked

              bytes_received:<bytes_received>
                     bytes received

              segs_out:<segs_out>
                     segments sent out

              segs_in:<segs_in>
                     segments received

              send <send_bps>bps
                     egress bps

              lastsnd:<lastsnd>
                     how long time since the last packet sent, the unit is millisecond

              lastrcv:<lastrcv>
                     how long time since the last packet received, the unit is millisecond

              lastack:<lastack>
                     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

              rcv_space:<rcv_space>
                     a helper variable for TCP internal auto tuning socket receive buffer

       -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.

       -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.

       --vsock
              Display vsock sockets (alias for -f vsock).

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

       -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. 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

       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

USAGE EXAMPLES

       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.

SEE ALSO

       ip(8),
       RFC 793 - https://tools.ietf.org/rfc/rfc793.txt (TCP states)

AUTHOR

       ss was written by Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>.

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

                                                                                            SS(8)