Solved

Cisco PIX - all interfaces on same subnet - possible?

Posted on 2002-06-11
5
350 Views
Last Modified: 2013-11-16
hi guys,

Would like to ask you if Cisco PIX can do a "drop-in configuration mode" i.e. allows you to drop a firewall(Physically between the Internet router and the internal LAN) into an existing network without subnetting or changing the subnet of the LAN hosts.

Basically which means the network interfaces are all from the same IP / network segment.

Also, would also like to confirm the routing given that the above is possible:
(1) Outgoing: the default gw for the PIX going to be the router?
(2) Outgoing: the hosts default gw going to be the inside interface of the PIX?
(3) Incoming: how does it work from the router point-of-view? Any routing required here?

Pls advice..! Thxs








0
Comment
Question by:Haho
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
5 Comments
 
LVL 79

Accepted Solution

by:
lrmoore earned 100 total points
ID: 7070015
No can do with PIX. Each interface must be a different subnet.
0
 
LVL 1

Expert Comment

by:Chriskohn
ID: 7071572
Hello Haho:
 Agree with Irmoore that you would need at least two subnet in order to define one security level being different than another.
 In answer to your other three questions:
1)Yes. You are correct in your thinking here.
2)Yes again you are correct.
3)Your router needs a default route to the Internet if that is way your going from here, or if still in an Intranet your routing may be static or dynamic depending on what you are trying to accomplish.
 Just as a suggestion to get around your dilemma of not having a second subnet, Perhaps you could try to use VLSM (variable length subnet masking) if your routing protocol supports it and if you aren't already. Depending on your IP addressing scheme at this time perhaps you could possibly provide a 2 IP address subnet just for your outside PIX interface and your router's Ethernet connected to it. Good luck, hope this helps Chriskohn
0
 
LVL 1

Author Comment

by:Haho
ID: 7071668
I found a posting that says that it can be on the same subnet.

Pls refer to:
http://www.geocrawler.com/archives/3/90/1997/5/0/373659/

> >We were informed that Cisco PIX 4.0 can perform the following :
> >1) PIX is transparent, the 2 network interfaces on PIX can be configured
> >   using IP addresses from the same network segment.
0
 
LVL 79

Expert Comment

by:lrmoore
ID: 7071779
The date of that posting was over 5 years ago and also states:
> This really would not make sense...  if the internal and external
> networks are on the same segment, then there`s no point in having
> the firewall.

It still doesn't make sense.

PIX 4.0 has come a long way, baby. The whole concept of the PIX is that you have one network at one security level and other networks at either higher or lower security levels. You cannot have two interfaces at two different security levels on the same subnet.

My opionion has not changed. No can do. Sorry if you don't like it.
0
 
LVL 1

Author Comment

by:Haho
ID: 7072384
ok, thanks!
0

Featured Post

Free learning courses: Active Directory Deep Dive

Get a firm grasp on your IT environment when you learn Active Directory best practices with Veeam! Watch all, or choose any amount, of this three-part webinar series to improve your skills. From the basics to virtualization and backup, we got you covered.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

No single Antivirus application (despite claims by manufacturers) will catch or protect you from all Virus / Malware or Spyware threats. That doesn't stop you from further protecting yourself however - and this article is to show you how.
Recently, Microsoft released a best-practice guide for securing Active Directory. It's a whopping 300+ pages long. Those of us tasked with securing our company’s databases and systems would, ideally, have time to devote to learning the ins and outs…
Nobody understands Phishing better than an anti-spam company. That’s why we are providing Phishing Awareness Training to our customers. According to a report by Verizon, only 3% of targeted users report malicious emails to management. With compan…
The Email Laundry PDF encryption service allows companies to send confidential encrypted  emails to anybody. The PDF document can also contain attachments that are embedded in the encrypted PDF. The password is randomly generated by The Email Laundr…

738 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question