Check what ports are open - Printable Version

Check what ports are open - Printable Version

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Check what ports are open - xDamox - 2005-01-16

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:

Code:
nmap -sS -O 127.0.0.1

once the scan has finished you will get the following ouput:

Code:
Starting nmap 3.70 ( http://www.insecure.org/nmap/ ) at 2005-01-16 05:48 GMT

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:

Code:
netstat -nap

This will show you the output of something similar to:

Code:
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

Check what ports are open - P38 - 2005-01-17

When you are looking for open ports on your machine, scanning 127.0.0.1 will not necessarily show you anything that is exposed. Most firewall configurations allow full access from the local machine to 127.0.0.1. If you are interested in determining what ports others might be able to see and potentially exploit, you should scan your machine from another machine to your IP address that is exposed to the external world.

Check what ports are open - znx - 2005-03-21

Adding to what P38 said.. scanning within a LAN will not show everything that is exposed either. Again the external IP is the way around this...

Check what ports are open - grep420 - 2005-03-24

I like to use netstat -ntulp that will show everything that is listening tcp and udp and the ip that it is listening on.

Check what ports are open - dspln - 2005-12-05

before I learned of netstat, I started using

lsof -i -n -P

seems to give a bit more info

(or just lsof to get a dump of all open files - long list :))