SS(8)                                                 System Manager's Manual                                                 SS(8)

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  connec‐
       tion.

       -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 factor and receive scale factor

              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 use‐
              ful 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.

       --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 fol‐
       lowed 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)

Usage: ss [ OPTIONS ]
       ss [ OPTIONS ] [ FILTER ]
   -h, --help          this message
   -V, --version       output version information
   -n, --numeric       don't resolve service names
   -r, --resolve       resolve host names
   -a, --all           display all sockets
   -l, --listening     display listening sockets
   -o, --options       show timer information
   -e, --extended      show detailed socket information
   -m, --memory        show socket memory usage
   -p, --processes     show process using socket
   -i, --info          show internal TCP information
       --tipcinfo      show internal tipc socket information
   -s, --summary       show socket usage summary
   -b, --bpf           show bpf filter socket information
   -E, --events        continually display sockets as they are destroyed
   -Z, --context       display process SELinux security contexts
   -z, --contexts      display process and socket SELinux security contexts
   -N, --net           switch to the specified network namespace name

   -4, --ipv4          display only IP version 4 sockets
   -6, --ipv6          display only IP version 6 sockets
   -0, --packet        display PACKET sockets
   -t, --tcp           display only TCP sockets
   -S, --sctp          display only SCTP sockets
   -u, --udp           display only UDP sockets
   -d, --dccp          display only DCCP sockets
   -w, --raw           display only RAW sockets
   -x, --unix          display only Unix domain sockets
       --tipc          display only TIPC sockets
       --vsock         display only vsock sockets
   -f, --family=FAMILY display sockets of type FAMILY
       FAMILY := {inet|inet6|link|unix|netlink|vsock|tipc|help}

   -K, --kill          forcibly close sockets, display what was closed
   -H, --no-header     Suppress header line

   -A, --query=QUERY, --socket=QUERY
       QUERY := {all|inet|tcp|udp|raw|unix|unix_dgram|unix_stream|unix_seqpacket|packet|netlink|vsock_stream|vsock_dgram|tipc}[,QUERY]

   -D, --diag=FILE     Dump raw information about TCP sockets to FILE
   -F, --filter=FILE   read filter information from FILE
       FILTER := [ state STATE-FILTER ] [ EXPRESSION ]
       STATE-FILTER := {all|connected|synchronized|bucket|big|TCP-STATES}
         TCP-STATES := {established|syn-sent|syn-recv|fin-wait-{1,2}|time-wait|closed|close-wait|last-ack|listening|closing}
          connected := {established|syn-sent|syn-recv|fin-wait-{1,2}|time-wait|close-wait|last-ack|closing}
       synchronized := {established|syn-recv|fin-wait-{1,2}|time-wait|close-wait|last-ack|closing}
             bucket := {syn-recv|time-wait}
                big := {established|syn-sent|fin-wait-{1,2}|closed|close-wait|last-ack|listening|closing}