ACL question

SteveFer

In Todds CCNA book, near the end of the EIGRP chapter, he talks about checking ACLs on a router for troubleshooting EIGRP, he says "For CCNA objectives, always check for an ACL on the actual interface, not just in the routing table " I'm a bit confused by the routing table part, how would an ACL be applied in a routing table, or would I check for an ACL in a routing table? I would always apply an ACL to an interface. Does he mean make sure to use commands that show which interfaces have ACLS, as opposed to ACLS that are on the router?

networker050184

No way to check for an ACL directly in the routing table, but maybe he meant to just verify what routes should be there are?

xnx

I think it means you have to check if an access list has been applied to an interface itself using 'ip access-group' in subinterface mode and also defining a direction in whcih to check a flow.

Specifically an ACL may be blocking the EIGRP transport protocol since it doesn't use TCP / UDP..

E.g:
R1(Config): int fa0/0
R1(Config-if): ip access-group 10 in

That will check ACL number 10 for all inbound flows towards the interface.

Extra point:
You can check your access lists with the show 'ip access-list' command, if you want to see a specific ACL rule then put the number or name after.