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SS

Section: Maintenance Commands (8)
Index Return to Main Contents

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.

-e, --extended

Show detailed socket information

-m, --memory

Show socket memory usage.

-p, --processes

Show process using socket.

-i, --info

Show internal TCP information.

-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.

-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, dccp, sctp.

-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, 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.