Solved

Internet access through T1 line down after replacing hardware firewall

Posted on 2007-03-28
4
218 Views
Last Modified: 2010-03-17
I need help with this potential employment question.  This is NOT an exam question, but part of a long list for me to research and get back within the next week:

"Your company has an internet connection supplied to the LAN from a hardware firewall connected to a T1 router.  During normal business hours the Internet goes down.  After checking the T1 router and the corporate firewall you find that the firewall has suffered a hardware failure.  You replace the hardware firewall with a spare firewall.  The spare firewall is the exact same model and runs the same firmware.  You use the configuration file that was in production on the failed firewall.  The configuration file is sound.  You shutdown the old firewall and remove it from the network and you install the new firewall with the same configuration file already in place.  You cable the firewall properly and it starts normally.  None of the systems on your network can get out to the Internet.  What is the highest probable cause for this issue and what do you do first to resolve the issue.  Also list other probable causes for the Internet connectivity issue."

My initial thinking is that the new hardware firewall, although identical in model, firmware, and configuration file, has a different MAC address, and there may be an issue with the T1 provider's router and this new address.  Secondly, could installing the firewall with the configuration file already in place be an issue, as opposed to running the configuration file after physically installing the hardware firewall?

Thanks in advance for any leads on this.
0
Comment
Question by:ScottAllen1980
4 Comments
 
LVL 8

Accepted Solution

by:
charan_jeetsingh earned 63 total points
ID: 18813338
MAC address is one probable issue as most of the times for security reasons this is done to avoid evesdropping. at the local end also you can try clearing the ARP table for proxy and the connecting switches.
0
 
LVL 4

Expert Comment

by:chatxfalcon
ID: 18814323
Firewalls is working on Layer 3 and above. MAC Address is on Layer 2

I believe the problem is not on the MAC. The most probable cause is the physical setup.

Please do the following:

1) Check your cables and make sure its on the right port.
2) Check the port if working (try ping the firewall's port)
3) From your workstation try ping the gateway of your firewall.(the next hop)


I hope this helps.. :)


 
0
 
LVL 3

Assisted Solution

by:nalanbar
nalanbar earned 62 total points
ID: 18816621
MAC address, more than likely. The thing to do is to traceroute, and see where the packets stop. If you hit the firewall, and then no further, then the most likely answer is that the router doesn't recognize the MAC of the firewall, and so is dropping the traffic inbound from it. The fix is to either spoof the old MAC (should be printed on the bottom of the old firewall :D), or to adjust the router, which is a better answer. The real question after the traceroute is wether you or the ISP owns the router. If it is you, then you fix it yourself, ISP, you call them.
0

Featured Post

How your wiki can always stay up-to-date

Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
- Increase transparency
- Onboard new hires faster
- Access from mobile/offline

Join & Write a Comment

We sought a budget ($5,000) firewall solution that would provide all the performance we needed with no single point of failure.  Hosting a SAAS web application in our datacenter, it was critical that we find a way to keep connectivity up and inbound…
Hi All,  Recently I have installed and configured a Sonicwall NS220 in the network as a firewall and Internet access gateway. All was working fine until users started reporting that they cannot use the Cisco VPN client to connect to the customer'…
In this tutorial you'll learn about bandwidth monitoring with flows and packet sniffing with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're interested in additional methods for monitoring bandwidt…
When you create an app prototype with Adobe XD, you can insert system screens -- sharing or Control Center, for example -- with just a few clicks. This video shows you how. You can take the full course on Experts Exchange at http://bit.ly/XDcourse.

758 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

Need Help in Real-Time?

Connect with top rated Experts

23 Experts available now in Live!

Get 1:1 Help Now