To reboot the PIX or not reboot - that is the question

Mar 14, 2006 1 Replies

All,



I have a head scratcher, brief details and topology:


DMZ - 172.18.1.0 / PIX 515 6.3(4) --outside X.X.X.X / inside



192.168.X.X + other networks

On the inside of the PIX I have various route statements to several networks. One of these is 172.31.0.0/16.



I use my DMZ router 172.18.1.X to connect to a number of other routers (via the outside interface of the PIX). These routers sit behind a Concentrator and use Loopback addresses in range 172.31.233.0/24.



The traffic off the DMZ in no-nated.



My problem, I am simply getting no hits on either my no-nat list or accompanying access-list on the PIX.



e.g.



access-list nonat permit ip 172.18.1.0 255.255.255.0 172.31.233.0



255.255.255.0

access-list blah permit ip 172.18.1.0 255.255.255.0 172.31.233.0



255.255.255.0

There is a default route on the PIX pointing to the outside router. Talking to my colleague he seems to think the PIX will be forwarding my



172.31.233.0 traffic towards the 172.31.0.0/16 entry on the inside. I am sure that the PIX wouldn't, either way, I cannot understand why I have not hits in my no-nat etc.

The above access-list & nonat entries are just 'tagged on additions' to the bottom of pre-configured working lists.



Anyone have any suggestions ?



Regards



Darren



------


He is correct.

Traffic from the inside to 172.31.233/24 is going to hit the inside interface; the PIX would see that the route is through the inside interface, and would promptly drop the packet -before- looking at any access lists.

You can create a route for 172.31.233/24 specifically, while still keeping your 172.31/16 route. The PIX uses "best match" routing, so traffic to 172.31.233/24 would match the specific route and traffic to any other 172.31/16 would use the 172.31/16 route (or get dropped, if the route would have it go back out the same interface it came in.)

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