Linux ss Command
In this tutorial, we will be discussing on how to use the ss command and we will be covering some of the topics on how to check network connections and socket statistics. ss command is a new IP tool command which provides higher information than netstat command. The ss command fetches data from many /proc files in order to provide the information to the user. In case the system has more connections to display then it might take some more time to show the information. Although the options of the netstat command and the ss command are similar it won’t cause any difficulty in using it.
Filter out tcp, udp or Unix connections
Options t, u or x provide the details of tcp or udp or Unix connections.
$ ss -t
State Recv-Q Send-Q Local Address:Port Peer Address:Port
ESTAB 0 128 66.45.225.231:ssh 202.83.46.160:26376
ESTAB 0 848 66.45.225.231:ssh 221.229.172.66:13489
To list only the udp connections, then use the option -ua
$ ss -ua
State Recv-Q Send-Q Local Address:Port Peer Address:Port
UNCONN 0 0 *:34624 *:*
UNCONN 0 0 *:bootpc *:*
UNCONN 0 0 *:49312 *:*
UNCONN 0 0 *:mdns *:*
UNCONN 0 0 :::32083 :::*
Output without resolving
Option n will help not to resolve the IP address to hostnames, this will provide better speed in getting outputs.
$ ss -nt
State Recv-Q Send-Q Local Address:Port Peer Address:Port
ESTAB 0 64 66.45.225.231:22 202.83.46.160:26376
LAST-ACK 0 1641 66.45.225.231:22 221.229.172.66:46379
3) Display listening sockets
The following command will list out all the listening sockets in the systems. The option t indicates all the tcp connections in the system
$ ss -ltn
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:22 *:*
LISTEN 0 100 127.0.0.1:25 *:*
LISTEN 0 128 :::80 :::*
To display the udp connections use the option u instead of t.
$ ss -lun
State Recv-Q Send-Q Local Address:Port Peer Address:Port
UNCONN 0 0 *:34624 *:*
UNCONN 0 0 *:68 *:*
UNCONN 0 0 *:49312 *:*
UNCONN 0 0 *:5353 *:*
UNCONN 0 0 :::32083 :::*
Display summary statistics
Statistics can be printed with the option s
$ ss -s
Total: 187 (kernel 240)
TCP: 7 (estab 1, closed 1, orphaned 0, synrecv 0, timewait 0/0), ports 0
Transport Total IP IPv6
* 240 – –
RAW 1 0 1
UDP 5 4 1
TCP 12 7 5
FRAG 0 0 0
Timer information
The information regarding the time of each connection can be obtained using the option –o. The duration of the connections also can be displayed.
$ ss -tn –o
Local Recv-Q Send-Q Address:Port Peer Address:Port
ESTAB 0 64 66.45.225.231:22 202.83.46.160:26376 timer:(on,521ms,0)
IPv4 and IPv6 socket connections
Options –f inet or -4 options help to view the IPv4 socket options.
$ ss -tl -f inet
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:ssh *:*
LISTEN 0 100 127.0.0.1:smtp *:*
Options -f inet6′ or -6 options help to view the IPv6 socket options.
$ ss -tl6
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 :::http :::*
LISTEN 0 128 :::ssh :::*
LISTEN 0 100 ::1:smtp :::*
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