Ubuntu Manpages

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 informations 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.

Show summary of options.
Output version information.
Do not try to resolve service names.
Try to resolve numeric address/ports.
Display both listening and non-listening (for TCP this means established connections) sockets.
Display only listening sockets (these are omitted by default).
Show timer information.
Show detailed socket information
Show socket memory usage.
Show process using socket.
Show internal TCP information.
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.
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.
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.
Switch to the specified network namespace name.
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).
Display TCP sockets.
Display UDP sockets.
Display DCCP sockets.
Display RAW sockets.
Display Unix domain sockets (alias for -f unix).
Display sockets of type FAMILY. Currently the following families are supported: unix, inet, inet6, link, netlink.
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.
Do not display anything, just dump raw information about TCP sockets to FILE after applying filters. If FILE is - stdout is used.
Read filter information from FILE. Each line of FILE is interpreted like single command line option. If FILE is - stdin is used.
Please take a look at the official documentation (Debian package iproute-doc) 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.

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

Display all TCP sockets.
Display all TCP sockets with process SELinux security contexts.
Display all UDP sockets.
Display all established ssh connections.
Find all local processes connected to X server.
List all the tcp sockets in state FIN-WAIT-1 for our apache to network 193.233.7/24 and look at their timers.

ip(8), /usr/share/doc/iproute-doc/ss.html (package iproute­doc),
RFC 793 - https://tools.ietf.org/rfc/rfc793.txt (TCP states)

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).