Finding out DHCP Servers

warned · 04-15-2004, 01:15 AM

Hi all there.

Does anybody know how can I obtain which servers are working as DHCP servers?? Do exist any command or application that I can use to do this??

I have a number of PCs that are connecting with DHCP but are obtaining IPs that my DHCP server did not provided to them, and I'd like to know if there is another server acting as DHCP server.

Thanks guys...

ugge · 04-15-2004, 01:24 AM

When you ask for an IP you broadcast a DCH request to all connected to the same broadcast domain (same cable, same hub/swithch).
All DHCP servers send a response provided that your client is good for an IP, which normally is every DHCP answering.

Your computer will normally take the IP of the first incoming answers.
You can have a look in the log /var/log/messages or run the dhcp client in debug mode as a foreground process to see what addresses you get offered and from where.

warned · 04-15-2004, 02:44 AM

Yes, ok, this solve this case, but I really need to locate every DHCP Server in the network "by hand". I used nmap this way:

# nmap -sU -P0 -p 67 <network>/<mask>

that works fine, but I'd like to know if perhaps exists an utility to do this.