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troubleshooting Question

Cisco 857W block outgoing smtp from all but mail server

Avatar of gamutgroup
gamutgroupFlag for Australia asked on
RoutersSoftware Firewalls
14 Comments1 Solution1293 ViewsLast Modified:
I've had a look at the solution described in https://www.experts-exchange.com/Security/Software_Firewalls/Q_22083224.html, and it's *almost* working but not quite. We have a similar situation in that some user has managed to infect at least one PC with a spambot. Worst of all, it doesn't appear to have been found yet, so it's still spamming away. We want to both block current attempts, and provide a framework to stop it happening in future.

I've implemented the following access list, but it's currently blocking all outgoing SMTP, regardless of the source.  The lines I'm putting in are as follows:

access-list 100 permit tcp any eq smtp
access-list 100 deny tcp any any eq smtp
access-list 100 permit ip any any
int dialer 0
ip access-group 100 out

However, after implementing this, looking at the show access-list shows all outgoing is blocked, and attempts to use SMTP out are blocked. I am a Cisco novice (the router was put in place by a 3rd party tech who has said he doesn't know how to do this) Can anyone help me with what I am missing?

The result from a show access-list is as follows:
Extended IP access list 100
    10 permit tcp host any eq smtp
    20 deny tcp any any eq smtp (21 matches)
    30 permit ip any any (69 matches)
Avatar of memo_tnt
memo_tntFlag of Palestine, State of image

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