How to allow the DHCP traffic

Unanswered Question
Dec 9th, 2008
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Hi ,


I have configured the internet link in cisco 1841 router. In that I have blocked the in bound traffic using access-list and blocked outbound traffic using IOS filter.

I have allowed outbound for ftp.http,https etc. inbound I have allowed icmp , esp, gre and isakmp only. I have enabled the DHCP client in router WAN interface so how to allow the DHCP traffic to inbound.





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royalblues Tue, 12/09/2008 - 08:27
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You will have to allow udp 67 and 68 for DHCP to work


You router will send a DHCP request which will have source as 0.0.0.0 and destination as a broadcast 255.255.255.255. The response would also be to the broadcast address 255.255.255.255.


You can try allowing UDP 67/68 from any address and then fine tune later


Narayan

jpoplawski Tue, 12/09/2008 - 08:30
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In your ACL that's on the outside interface add the following line

"permit udp any any eq bootps"

Test it and see if it works appropriately.


Hope this helps, rate if it does.

JB

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