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New Member

Log output from an ACL

When you implement an ACL (standard/extended etc), you can choose the option of "log-input" to output any packets that are allowed/disallowed as per your ACL. Is there a document that help you interpret this log output? For a specific example,:

Apr 16 08:59:55.620 PDT: 133 permitted icmp -> (8/0), 1 packet

Now I figured the router allowed an ICMP packet pass from host to host However, I am unsure what "(8/0)" means. What would be really good is a reasonably comprehensive document that explains how to intepret the log output in general . I've searched the Cisco website, but am struggling to find the relevant document.

Any help appreciated.



Cisco Employee

Re: Log output from an ACL

Not sure if there's any documentation on this specifically.

For an ICMP ACL, the 8/0 refers to the ICMP type and code (type/code). These can be found in a multitude of places on the Internet, here's one ( For 8/0, this is an ICMP Echo packet (a ping).

For TCP/UDP ACL's, this value will just be one value (no / in there), and this will indicate the TCP/UDP port number. If I remember correctly, this number will show up on both the source and the destination IP addresses, indicating the source and destination port number in the packet.