topic Re: ACL's blocking DHCP in Network Security

ACL's blocking DHCP

Areyouserious — Fri, 21 Feb 2020 16:24:56 GMT

Hi all.

I have a cisco 2811 behind a bridged broadband modem. The link is configured on one of the router ports is DHCP.

I have an ACL on this port that denies all traffic coming inbound, as well as CBAC enabled to inspect traffic going outbound.

Problem is DHCP traffic between the router and the modem is being blocked. Hence a link can't be established.

I've had a look at some exqmples of enabling dhcp ports on this link but not too sure how to configure dhcp safely.

just wondering if anyone could help me.

Thanks

balaji.bandi — Tue, 30 Oct 2018 20:35:48 GMT

it would nice if you an post the running configuration, so we can suggest to working possibilities.

basic access-list for DHCP

access-list 10 permit udp any eq bootpc any eq bootps

Areyouserious — Mon, 05 Nov 2018 08:52:53 GMT

10 permit udp any any eq bootpc Works perfectly!

Thankyou