How to configure a firewall to communicate with an upstream router

How to configure a firewall to communicate with an upstream router

My client is using the same vendor for his routers and switches, but is now trying to incorporate a new firewall product from a different vendor. We are having configuration problems, and the firewall is not communicating with the upstream router. When this occurs, what are the most common causes?

    Requires Free Membership to View

    SearchSecurity.com members gain immediate and unlimited access to breaking industry news, virus alerts, new hacker threats, highly focused security newsletters, and more -- all at no cost. Join me on SearchSecurity.com today!

    Michael S. Mimoso, Editorial Director

    By submitting your registration information to SearchSecurity.com you agree to receive email communications from TechTarget and TechTarget partners. We encourage you to read our Privacy Policy which contains important disclosures about how we collect and use your registration and other information. If you reside outside of the United States, by submitting this registration information you consent to having your personal data transferred to and processed in the United States. Your use of SearchSecurity.com is governed by our Terms of Use. You may contact us at webmaster@TechTarget.com.

There's no reason that you should have to purchase your firewalls and other networking equipment from the same vendor. In fact, I've never done this in any of the enterprises where I've worked or consulted in the past. Your firewall should be able to interoperate with any network infrastructure that you put in place. That's the whole point behind using standards such as TCP/IP for network communications.

I suspect that you're experiencing one of many simple networking problems. It could be that the switch/router port that your firewall is connected to is incorrectly configured. Perhaps the network interface in the firewall is defective. Are you certain that you've applied an appropriate IP address to the firewall's interface?

My recommendation is to approach this problem in the same manner as you'd handle any device that you're not able to connect to your network. Check the simple things first (link lights, IP configuration, etc.) and then expand outward to more advanced techniques, such as sniffing the network segment using a tool like Wireshark.

More information:

  • A SearchSecurity.com reader asks Mike Chapple, "Will there be DMZ routing issues if several firewalls serve as the default gateway?"
  • Get the latest news and expert advice on network firewalls.
  • This was first published in January 2009