There are two good methods to see what ports are open in Linux you can use
nmap which is a port scanner and you can use netstat.
nmap can be used to scan your machine to see whats ports are open issue the
following command to scan your computers machine:
once the scan has finished you will get the following ouput:
Interesting ports on localhost.localdomain (127.0.0.1):
(The 1656 ports scanned but not shown below are in state: closed)
PORT STATE SERVICE
22/tcp open ssh
80/tcp open http
443/tcp open https
1241/tcp open nessus
Device type: general purpose
Running: Linux 2.4.X|2.5.X|2.6.X
OS details: Linux 2.5.25 – 2.6.3 or Gentoo 1.2 Linux 2.4.19 rc1-rc7)
Uptime 1.985 days (since Fri Jan 14 06:10:41 2005)
Nmap run completed — 1 IP address (1 host up) scanned in 2.341 seconds
The second method was netstat. netstat can show hidden ports and what programs using
them issue the following command as root:
This will show you the output of something similar to:
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 127.0.0.1:61931 0.0.0.0:* LISTEN 5277/wish
tcp 0 0 127.0.0.1:5335 0.0.0.0:* LISTEN 3920/mDNSResponder
tcp 0 0 0.0.0.0:1241 0.0.0.0:* LISTEN 31438/nessusd: wait
tcp 0 0 10.0.0.14:32776 194.109.129.220:6667 ESTABLISHED 5062/xchat
tcp 0 0 10.0.0.14:45731 207.46.107.146:1863 ESTABLISHED 5277/wish
tcp 0 0 10.0.0.14:33009 82.96.64.2:6667 ESTABLISHED 5062/xchat
tcp 0 0 :::80 :::* LISTEN 4355/httpd
tcp 0 0 :::22 :::* LISTEN 32372/sshd
tcp 0 0 :::443 :::* LISTEN 4355/httpd
udp 0 0 0.0.0.0:68 0.0.0.0:* 3614/dhclient
udp 0 0 0.0.0.0:5353 0.0.0.0:* 3920/mDNSResponder