Shell script: list all hosts in a network

[Elif Gius]

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?

[Martin Brachtl · Accepted solution]

use ping with broadcast address.

[Kasper Hedensted]

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,

[Simon Hargrave]

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

[Elif Gius]

thanks all for the fast reply ...
Great!