Add a firewall and it won't connect

[MountainNetworks]

Hi:

Just wondering if anyone else has run into this before.

The client has a network of 5 PCs all connected via DSL with a Cayman Series Netopia box. The Cayman box has 4 ports and the client has static IPs or DHCP. We added a Linksys BEFSR41 for network firewall protection and NAT. It works great...no problems whatsoever.

The client wanted to add a public PC that is not connected to their network. So we rebuilt an old workstation with Windows XP Professional, fully updated with all servicepacks and hotfixes.

We run a cat5 cable from port 2 of the cayman netopia series dsl modem directly into the PC and it works just fine. We get an IP address and internet connectivity. But if we add a firewall device of any make or model, the network light on the network card of the public PC doesn't even light up. So there's no connection at all.

Let me try and summarize this network for you in ascii pictures

Internet----DSL (Cayman Series Netopia)
|
X--X--X--X
1--2--3--4
| |----------------------------------|
| |
WAN--X--X--X--X (Linksys BEFSR41) |
| | | | |
---PC1-PC2-PC3-PC4 |
|
|
Public PC-----------------------------|

This configuration works fine. But if I add a firewall device of any type, the public PC's network card doesn't recognize any connection. So the configuration below WON'T work:

Internet----DSL (Cayman Series Netopia)
|
X--X--X--X
1--2--3--4
| |----------------------------------|--2nd Linksys (or ?)
| |
WAN--X--X--X--X (Linksys BEFSR41) WAN--X--X--X--X
| | | | |
---PC1-PC2-PC3-PC4 |
|
|
Public PC-------------------------------------|


I hope that helps and doesn't confuse the issue further. Any ideas?

 

[bcastner]

Disable DHCP on the BEFSR41.

 

[bcastner]

I'm sorry, I misread the diagram.
My guess is that one of the cables is either faulty, or the wrong type. My guess would be you need a cross-over cable between the modem and the Linksys WAN port.

 

[MountainNetworks]

My diagram didn't post the same way I wrote it. Anyway...

Cables...I thought about that. But then why does the other one work? I've also tried cables that I know work on other PCs. What perplexes me is that the PC's network card doesn't give me a network connected green light when I plug it into the firewall device.

The working network goes from the Cayman device, to the Linksys Device, and all the PCs are plugged into the Linksys device ports. They all use static IP and DHCP is turned off. Everything is cat5 cable...no crossover and everything works...go figure...

But when I run another cat5 cable from the cayman device, to another Linksys Device, the public PC won't even register a live network (network connection is disabled) when I plug the PC into an available port in the second linksys device. However, if I take the second Linksys device away and plug it directly into the internet, it'll connect just fine.

 

[netmanrick]

On the public pc,when it's connected to the Linksys.
Do a ipconfig command.What does it indicate;ipstack,DNS,gateway,ipaddress,netmask?????

Rick Harris
SC Dept of Motor Vehicles
Network Operations

 

[MountainNetworks]

Rick:

On the public PC, I can't do an ipconfig because when it's connected to the Linksys, the link light on the NIC in the PC itself won't turn on. "Network is unplugged" ...

The BIOS reflects some ACPI errors. I've purchased the latest BIOS upgrade from Award. After I upgrade the BIOS, I'll update the posting and advise how it went.

 

[dearingkr]

Sounds like the Netopia box is only allowing 1 device attached at a time. Check its DHCP. You may have some MAC filtering going on there too.

What happens when you put static IP's on the WAN's of both Linksys boxes?