topic Inside Outside IP the same? in Network Security

Inside Outside IP the same?

geelsu — Tue, 12 Mar 2019 01:04:08 GMT

I have inherited a PIX 525 environment and I need to document a lot of stuff to catch-up on what is going on. I was gathering IP address information and ran "show interface outside" and "show interface inside" and noticed the same IP assigned to both. I checked the MAC address and they are different. This IP is also listed as the Management IP. So I am sort of confused. What condition would warrant both the inside interface and outside interface along with the Management IP having the same IP?

The PIX and the hosts it comms it monitors do live in a VLAN controlled by a Brocade switch which also is our gateway out.

Can someone help me understand this IP address senario?

Thanks to all

PIX Version 7.1(1)

ASDM Version 5.1(1)

Inside Outside IP the same?

Jouni Forss — Fri, 22 Feb 2013 13:35:10 GMT

Hi,

Can you share some configurations from the PIX firewall?

- Jouni

Inside Outside IP the same?

geelsu — Fri, 22 Feb 2013 13:37:51 GMT

Sure. I will have to hand-type it since it is on a secure network not attached and not attached to the Internet. Let me know what you would like.

Inside Outside IP the same?

Jouni Forss — Fri, 22 Feb 2013 13:40:39 GMT

Hi,

I'm mostly wondering about the whole thing about same IP address being on 2 different interfaces. I think it should not even be possible to configure a Cisco firewall in that way.

- Jouni

Inside Outside IP the same?

James Leinweber — Fri, 22 Feb 2013 15:21:20 GMT

Is the firewall running in transparent mode or routed mode? In transparent mode the difference between inside and outside the the switch vlans, not the traffic addresses. What does show firewall say?

-- Jim Leinweber, WI State Lab of Hygiene

Inside Outside IP the same?

geelsu — Mon, 25 Mar 2013 18:04:03 GMT

Hey James, and all,

Sorry for the major delay to your question. I checked and it is indeed running in transparent mode. I am not sure what that means, but will do some research on it.

George