homecomputerlab

I feel a little guilty for not posting anything for a while so today’s hot tip is how to ping an entire subnet. Comes in handy when documentation isn’t properly up to date; looking for a certain server/service on a network or when you are working on an unfamiliar network and want to get a quick idea of what is running where. Of course nmap is a lot more powerful than this, but that is a topic for a later, much longer post.

For a quick summary of whats on a subnet:
nmap -sP 192.168.0.0/24

Starting Nmap 5.00 ( http://nmap.org ) at 2011-04-19 23:33 BST
Host AP7920 (192.168.0.95) is up (0.0091s latency).
Host fitpc (192.168.0.100) is up (0.0018s latency).
Host 192.168.0.244 is up (0.018s latency).
Host netbotz200 (192.168.0.251) is up (0.0094s latency).
Host 3com2924 (192.168.0.252) is up (0.0063s latency).
Host cisco887w (192.168.0.254) is up (0.0053s latency).
Nmap done: 256 IP addresses (6 hosts up) scanned in 7.71 seconds

For more detailed info of whats on a subnet:
nmap 192.168.0.0/24

Interesting ports on AP7920 (192.168.0.95):
Not shown: 998 closed ports
PORT   STATE SERVICE
22/tcp open  ssh
80/tcp open  http

Interesting ports on fitpc (192.168.0.100):
Not shown: 996 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
139/tcp  open  netbios-ssn
445/tcp  open  microsoft-ds

Interesting ports on 192.168.0.244:
Not shown: 998 closed ports
PORT   STATE SERVICE
22/tcp   open  ssh
80/tcp open  http

Interesting ports on netbotz200 (192.168.0.251):
Not shown: 998 closed ports
PORT   STATE SERVICE
22/tcp   open  ssh
80/tcp open  http

Interesting ports on 3com2924 (192.168.0.252):
Not shown: 997 closed ports
PORT    STATE SERVICE
7/tcp   open  echo
80/tcp  open  http
443/tcp open  https

Interesting ports on cisco887w (192.168.0.254):
Not shown: 999 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh

Nmap done: 257 IP addresses (6 hosts up) scanned in 76.71 seconds