Using Netstat 

Netstat comes with all Linux distros, is used for all sort of network-configuration queries.

# netstat -natp | grep LISTEN | sort
Active Internet connect ions (servers and established)
Proto Local Address     Remote    State   PID/Program name   
tcp   0.0.0.0:21        0.0.0.0:* LISTEN  797/tcpserver       
tcp   0.0.0.0:22        0.0.0.0:* LISTEN  718/sshd            
tcp   0.0.0.0:25        0.0.0.0:* LISTEN  17592/master        
tcp   0.0.0.0:465       0.0.0.0:* LISTEN  17592/master        
tcp   0.0.0.0:995       0.0.0.0:* LISTEN  1636/stunnel        
tcp   0.0.0.0:7777      0.0.0.0:* LISTEN  23476/sshd          
tcp   0.0.0.0:10091     0.0.0.0:* LISTEN  1774/stunnel        
tcp   0.0.0.0:10092     0.0.0.0:* LISTEN  1776/stunnel        
tcp   0.0.0.0:10093     0.0.0.0:* LISTEN  1778/stunnel        
tcp   0.0.0.0:10094     0.0.0.0:* LISTEN  1780/stunnel        
tcp   127.0.0.1:53      0.0.0.0:* LISTEN  29019/dnscache