DHCP protocol and rules

dracunciliasis · Aug 28, 2006, 3:54 PM

Hello

I want to block all traffic in one interface except the DHCP traffic and http traffic. The http I think I know how to allow it, but the DHCP I don’t have a clue of which protocol should I allow: TCP, UDP ICMP and in which port.

Does anybody have it done?
Thankyou
dracunciliasis

Gertjan · Aug 28, 2006, 8:38 PM

@dracunciliasis:

Does anybody have it done?

'DHCP' might just be one of the best documented protocols on the Internet (and still, in 2006 things aren't always clear).
So, yes - we all have the answer (as we have Google :)).
A first link gave me http://www.dhcp-handbook.com/dhcp_faq.html "for starters…" (look at question/answer A.7).

Short answer : it uses UDP on port 67 & 68.