Open Ports List
To see what ports are open, run command

netstat -nal

and check on TCP and UDP ports in the listing. To see what processes are bound to what ports, run as root

netstat -nalp


root@engdebian:~# netstat -nalp | more
 
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name   
tcp        0      0 0.0.0.0:515             0.0.0.0:*               LISTEN       1742/lpd Waiting    
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN       1726/exim4          
tcp        0      0 192.168.1.101:1040      128.6.238.10:22         ESTABLISHED  2229/ssh            
tcp        0      0 192.168.1.101:1024      128.6.238.12:993        ESTABLISHED  2195/pine           
tcp6       0      0 :::22                   :::*                    LISTEN       1813/sshd           
udp        0      0 0.0.0.0:68              0.0.0.0:*                            2085/dhclient

Similarly,

netstat -n --inet --listening --programs

Also, the processes responsible for the open ports can be identified with

lsof -i

See example.
Syntax of lsof:

lsof -i [TCP|UDP][@host][:port]

To list all open files for specific processes:

lsof -p PID 
lsof -c COMMAND
lsof -u username

To list all open files

lsof

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