Could anyone help me with a simple explanation for the below ACL and what does have to do with DHCP server and IP address requests coming from hosts...

access-list 112 permit udp any eq bootpc any eq bootps

Thanks, Ethem

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access-list 112 permit udp any eq bootpc any eq bootps

Whatever interface this is attached to is permitting any upd bootp client requests destined for any bootp server.

So if a client on that interface sends a bootp request it will be forwarded to a bootp server.

  • It is there to allow client DHCP requests across the interface. While they do different things, BOOTP and DHCP both use udp ports 67 and 68. – TAndrews Jan 17 '17 at 17:21

The ACL is going to catch layer 3 stuff. DHCP happens largely at Layer 2 (link layer). You will often see ip helper-address <DHCP SRVR ADD> on the LAN/subnet interface directing DHCP request on to a remote server.

That ACL line is in there probably becuase there is an overall ACL on that interface and they had to add that line to allow the DHCP request to reach the remote server (to bypass the explicit deny at the end of the ACL).

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