ss: Display Linux TCP / UDP Network and Socket Information
by Vivek Gite on June 2, 2009 · 9 comments
The ss command is used to show socket statistics. It can display stats for PACKET sockets, TCP sockets, UDP sockets, DCCP sockets, RAW sockets, Unix domain sockets, and much more. It allows showing information similar to netstat command. It can display more TCP and state information than other tools. It is a new, incredibly useful and faster (as compare to netstat) tool for tracking TCP connections and sockets. SS can provide information about:
All TCP sockets.
All UDP sockets.
All established ssh / ftp / http / https connections.
All local processes connected to X server.
Filtering by state (such as connected, synchronized, SYN-RECV, SYN-SENT,TIME-WAIT), addresses and ports.
All the tcp sockets in state FIN-WAIT-1 and much more.
Most Linux distributions are shipped with ss and many monitoring tools. Being familiar with this tool helps enhance your understand of what's going on in the system sockets and helps you find the possible causes of a performance problem.
Task: Display Sockets Summary
List currently established, closed, orphaned and waiting TCP sockets, enter:
# ss -s
Sample Output:
Total: 734 (kernel 904)
TCP: 1415 (estab 112, closed 1259, orphaned 11, synrecv 0, timewait 1258/0), ports 566
Transport Total IP IPv6
* 904 - -
RAW 0 0 0
UDP 15 12 3
TCP 156 134 22
INET 171 146 25
FRAG 0 0 0
Task: Display All Open Network Ports
# ss -l
Sample Output:
ss -l
Recv-Q Send-Q Local Address:Port Peer Address:Port
0 0 127.0.0.1:smux *:*
0 0 127.0.0.1:10024 *:*
0 0 127.0.0.1:10025 *:*
0 0 *:3306 *:*
0 0 *:http *:*
0 0 *:4949 *:*
0 0 *:domain *:*
0 0 *:ssh *:*
0 0 *:smtp *:*
0 0 127.0.0.1:rndc *:*
0 0 127.0.0.1:6010 *:*
0 0 *:https *:*
0 0 :::34571 :::*
0 0 :::34572 :::*
0 0 :::34573 :::*
0 0 ::1:rndc :::*
Type the following to see process named using open socket:
# ss -pl
Find out who is responsible for opening socket / port # 4949:
# ss -lp | grep 4949
Sample output:
0 0 *:4949 *:* users:(("munin-node",3772,5))
munin-node (PID # 3772) is responsible for opening port # 4949. You can get more information about this process (like memory used, users, current working directory and so on) visiting /proc/3772 directory:
# cd /proc/3772
# ls -l
Task: Display All TCP Sockets
# ss -t -a
Task: Display All UDP Sockets
# ss -u -a
Task: Display All Established SMTP Connections
# ss -o state established '( dport = :smtp or sport = :smtp )'
Task: Display All Established HTTP Connections
# ss -o state established '( dport = :http or sport = :http )'
Task: Find All Local Processes Connected To X Server
# ss -x src /tmp/.X11-unix/*
Task: List All The Tcp Sockets in State FIN-WAIT-1
List all the TCP sockets in state -FIN-WAIT-1 for our httpd to network 202.54.1/24 and look at their timers:
# ss -o state fin-wait-1 '( sport = :http or sport = :https )' dst 202.54.1/24
How Do I Filter Sockets Using TCP States?
The syntax is as follows:
## tcp ipv4 ##
ss -4 state FILTER-NAME-HERE
## tcp ipv6 ##
ss -6 state FILTER-NAME-HERE
Where FILTER-NAME-HERE can be any one of the following,
established
syn-sent
syn-recv
fin-wait-1
fin-wait-2
time-wait
closed
close-wait
last-ack
listen
closing
all : All of the above states
connected : All the states except for listen and closed
synchronized : All the connected states except for syn-sent
bucket : Show states, which are maintained as minisockets, i.e. time-wait and syn-recv.
big : Opposite to bucket state.
Examples
Type the following command to see closing sockets:
ss -4 state closing
Recv-Q Send-Q Local Address:Port Peer Address:Port
1 11094 75.126.153.214:http 175.44.24.85:4669
How Do I Matches Remote Address And Port Numbers?
Use the following syntax:
ss dst ADDRESS_PATTERN
## Show all ports connected from remote 192.168.1.5##
ss dst 192.168.1.5
## show all ports connected from remote 192.168.1.5:http port##
ss dst 192.168.1.5:http
ss dst 192.168.1.5:smtp
ss dst 192.168.1.5:443
Find out connection made by remote 123.1.2.100:http to our local virtual servers:
# ss dst 123.1.2.100:http
Sample outputs:
State Recv-Q Send-Q Local Address:Port Peer Address:Port
ESTAB 0 0 75.126.153.206:http 123.1.2.100:35710
ESTAB 0 0 75.126.153.206:http 123.1.2.100:35758
How Do I Matches Local Address And Port Numbers?
ss src ADDRESS_PATTERN
### find out all ips connected to nixcraft.com ip address 75.126.153.214 ###
## Show all ports connected to local 75.126.153.214##
ss src 75.126.153.214
## http (80) port only ##
ss src 75.126.153.214:http
ss src 75.126.153.214:80
## smtp (25) port only ##
ss src 75.126.153.214:smtp
ss src 75.126.153.214:25
How Do I Compare Local and/or Remote Port To A Number?
Use the following syntax:
## Compares remote port to a number ##
ss dport OP PORT
## Compares local port to a number ##
sport OP PORT
Where OP can be one of the following:
<= or le : Less than or equal to port
>= or ge : Greater than or equal to port
== or eq : Equal to port
!= or ne : Not equal to port
< or gt : Less than to port
> or lt : Greater than to port
Note: le, gt, eq, ne etc. are use in unix shell and are accepted as well.
Examples
###################################################################################
### Do not forget to escape special characters when typing them in command line ###
###################################################################################
ss sport = :http
ss dport = :http
ss dport \> :1024
ss sport \> :1024
ss sport \< :32000
ss sport eq :22
ss dport != :22
ss state connected sport = :http
ss \( sport = :http or sport = :https \)
ss -o state fin-wait-1 \( sport = :http or sport = :https \) dst 192.168.1/24
ss vs netstat Speed
Use the time command to run both programs and summarize system resource usage. Type the netstat command as follows:
# time netstat -at
Sample outputs:
real 2m52.254s
user 0m0.178s
sys 0m0.170s
Now, try the ss command:
# time
Sample outputs:
real 2m11.102s
user 0m0.124s
sys 0m0.068s
Note: Both outputs are taken from reverse proxy acceleration server running on RHEL 6.x amd64.
