Linux Command - netstat

netstat – Network Statistics

This command is used to display all the network connections, routing tables and number of network interface.

Example:  The below command list all the java instance running on the system

# netstat --all --programs --numeric | grep java
# netstat –apn | grep java

How to check whether the specific port is listening on the system?
# netstat --listening  --numeric –programs | grep port_number

Example: To check whether 8080 port is listening

# netstat --listening --numeric –programs | grep 8080
# nestat –lnp | grep 8080

Some important options in netstat command

# netstat --all                  
# netstat --route          
# netstat --interfaces