netstat command one liners

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Command netstat displays various network related information such as network connections, routing tables, interface statistics, masquerade connections, multicast memberships etc.

1.       List All Ports (both listening and non-listening ports)

# netstat -a

2.       Active UNIX domain sockets (servers and established)

List all tcp ports using netstat -at

# netstat –at

List all udp ports using netstat -au

# netstat -au

3.       List Sockets which are in Listening State

List only listening ports using netstat -l

# netstat -l

List only listening TCP Ports using netstat -lt

# netstat -lt

List only listening UDP Ports using netstat -lu

# netstat -lu

List only the listening UNIX Ports using netstat -lx

# netstat -lx

4.       Show the statistics for each protocol

Show statistics for all ports using netstat -s

# netstat -s

Show statistics for TCP (or) UDP ports using netstat -st (or) -su

# netstat -st

# netstat -su

5.       Display PID and program names in netstat output using netstat -p

This will add the “PID/Program Name” to the netstat output. This is very useful while debugging to identify which program is running on a particular port.

# netstat -pt

6.       Don’t resolve host, port and user name in netstat output

When you don’t want the name of the host, port or user to be displayed, use netstat -n option. This will display in numbers, instead of resolving the host name, port name, user name.

This also speeds up the output, as netstat is not performing any look-up.

# netstat -an

If you don’t want only any one of those three items ( ports, or hosts, or users ) to be resolved, use following commands.

# netsat -a --numeric-ports

# netsat -a --numeric-hosts

# netsat -a --numeric-users

7.       Print netstat information continuously

netstat will print information continuously every few seconds.

# netstat -c

8.       Find the non-supportive Address families in your system

netstat --verbose

At the end, you will have something like this.

 netstat: no support for `AF IPX' on this system.

 netstat: no support for `AF AX25' on this system.

 netstat: no support for `AF X25' on this system.

 netstat: no support for `AF NETROM' on this system.

9.       Display the kernel routing information using netstat -r

# netstat -r

Note: Use netstat -rn to display routes in numeric format without resolving for host-names.

10.   Find out on which port a program is running

# netstat -ap | grep ssh

11.   Find out which process is using a particular port:

# netstat -an | grep ':80'

12.   Show the list of network interfaces

# netstat -i

Display extended information on the interfaces (similar to ifconfig) using netstat -ie:

# netstat -ie

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