topic Re: Shell script: list all hosts in a network in Operating System - Linux

Shell script: list all hosts in a network

Elif Gius — Thu, 28 Jul 2005 04:06:22 GMT

Hi
i want to discover which IPs are in used in a network.

I want to do something like:

nslookup 146.16.14.[1-254]

Any ideas?

Re: Shell script: list all hosts in a network

Martin Brachtl — Thu, 28 Jul 2005 04:11:44 GMT

use ping with broadcast address.

Re: Shell script: list all hosts in a network

Kasper Hedensted — Thu, 28 Jul 2005 04:16:27 GMT

Hi,

You could do this in a script:
i=0;while [ $i -le 254 ]; do nslookup 146.16.14.$i ; i=$((i+1));done
but it assumes that reverse lookup has been set for each IP-address on the DNS server.

Perhaps instead of nslookup, you could get a list from the DNS server ?

You could also tried and ping every ip-address in that segment, and see which ip-addresses that doesn't respond. But this assumes that the hosts are up and allowing icmp.

Cheers,

Re: Shell script: list all hosts in a network

Simon Hargrave — Thu, 28 Jul 2005 04:17:32 GMT

Your question confuses slightly.

If you want to find all IP addresses currently active on your subnet then do as martin says:

# ping 146.16.14.255

then every alive machine will respond.

However your question also mentions nslookup, so perhaps you want to query your DNS for all IP addresses that have names? If so then

i=1
while [ i -lt 255 ]; do
nslookup 146.16.14.$i | grep -i name
(( i = i + 1 ))
done

Re: Shell script: list all hosts in a network

Elif Gius — Thu, 28 Jul 2005 04:41:21 GMT

thanks all for the fast reply ...
Great!