PIX configuration: enable ICMP type 3 code 4 from outside

Posted on 2005-04-06
Medium Priority
Last Modified: 2013-11-29
I'm a newbie to CISCO PIX firewalls. My problems is to allow ICMP packages of type 3 code 4 (defragmentation needed) from a specific DSL router to the internal network interface. The following line should allow ICMP type 3 packages - does this allow all subtypes or maybe  just code 0 or 1?

PIX1#icmp permit host unreachable outside

How can I specify the type a little bit more specific? Thanks for any help.

Kind regards,
Question by:mw-solutions
1 Comment
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Accepted Solution

gpriceee earned 150 total points
ID: 13716238
"to allow ICMP packages of type 3 code 4 (defragmentation needed)"
icmp permit xxxxxxxxxxx unreachable is type 3 and all subtypes

"from a specific DSL router to the internal network interface"
icmp permit xxxxxxxxxxxxxxxxxxxx outside does NOT permit the packets to the inside interface

"How can I specify the type a little bit more specific"
You have specified the type; there is no command for the sub-type.

icmp permit host unreachable inside

The issue I see with this--unless you're using this to maintain a vpn--is that hopefully you've simply replaces the ip address of the DSL router with the non-routable  If not, you need to replace the with the public address of the DSL router: the external interface address.

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