Tuesday, 5 December 2017

[Linux] ss Command. Advanced command more than netstat

#> ss -atn


Manual of ss command

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 connection.

       -h, --help
              Show summary of options.

       -V, --version
              Output version information.

       -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.

       -e, --extended
              Show detailed socket information

       -m, --memory
              Show socket memory usage.

       -p, --processes
              Show process using socket.

       -i, --info
              Show internal TCP information.

       -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).

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

       -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.

       -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 (Debian package iproute-doc) 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, listen and closing.

              all - for all the states

              connected - all the states except for listen 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.

SEE ALSO
       ip(8), /usr/share/doc/iproute-doc/ss.html (package iproutedoc),
       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)

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