Networking Linux box (knoppix 3.4) with Windows XP PC

[Harry Kuhman]

The modem is a SpeedStream 5100 and I believe it does not have a built-in router. ...

It may well not have a router or do NAT, but seeing the two different 102.168.xxx.xxx subnets is pretty strange. It's also strange that the router even passed a 192.168.xxx.xxx address out the upstream port to get to the modem, as this should not be considered a routable address.

Still, it would be wise to double check and be sure that the modem is not also acting like a NAT router. Thinking about it, there is an easy way to do this. You router will have some sort of status page that shows if you are connected or not and, when connected, will show your assigned IP address. This is the IP address that the router uses to talk to the Internet, not it's local 192.168.1.1 address. Look at that address. If (in your case) it begins with 68, 69, or 166, then the router is getting a real Internet address and all is right. However, if your router reports that the IP address it is seeing for the Internet is 192.168.0.xxx, then the modem does indeed do NAT and one level of NAT should be disabled.

I booted both systems from Knoppix 3.4 CD and was able to succcessfully ping each PC from the other...... I was able to ping all addresses from each PC booted from Knoppix 3.4.

Good. Sounds like your original problem has been resolved, pinging between all system now works. I'm not going to be any help with Linux networking, but I've seen lots of people discusssing it in this forum. I expect if you scan the old posts you'll find more than enough information.

I also found out that Service Pack 2 was installed on my Windows PC so I uninstalled that because it has caused nothing but problems so far, and also because I have other means of protecting that PC.

Yea, I thought that might be a factor. I would still strongly suggest using a software firewall (in addition to the router firewall), but I would never trust the Microsoft firewalls (reasons too many to list). There are other firewalls out there that will work with XP.

There is a self test option at the modem address (192.168.0.1) that allows you to ping addresses to test connectivity. When I tried to ping my systems while at 192.168.0.1, it timed out. But then when I pinged from the console it worked fine.

I'm not really following this, not sure what "at 192.168.0.1" means or "from the console" means. I thought that you had told me that you could ping the 192.168.0.1 address from bothe of the computers (192.168.1.100 and 192.168.1.101). What "being at 192.168.0.1" meane eludes me.

The modem is a SpeedStream 5100 and I believe it does not have a built-in router. There is a self test option at the modem address (192.168.0.1) that allows you to ping addresses to test connectivity. When I tried to ping my systems while at 192.168.0.1, it timed out. But then when I pinged from the console it worked fine.

When I visit 192.168.0.1 I get all my internet service info. I can reset modem, changed modem codes, get loggs and statitics reports, check and change IP address assignment lease time, see MAC address, PPP location, PPPoE...

I guess I could spend some time tracking down this device and see what it has. But the idea that it deals with IP address lease time and the rest of the things you mentioned above really makes me think again that this device is doing NAT (you had me thinking it was not up to this point). So I really think you should look at the external router and see what IP address it thinks it's geting from the Internet, If it is a 192.168.0.xxx address, then you really really want to disable one level of NAT. With two NAT levels going on you'll slow your connection needlessly. More importantly, you'll never be able to use port forwarding, the DMZ feature, or some other features of your router.

So I think you are right when you said it's a Windows problem. But then when I re-booted Windows without SP2 installed and making sure the system was not blocking pinging, it still didn't work. I even changed a setting at 192.168.1.1 where I can block WAN requests (pings) to allow for access to my system... I am not sure what is going on.

Well, we know the local network is fine and you can ping one computer from another. I don't know how you removed SP2 or how sucessful that is. I do know that even before SP2, Xp had a firewall (not a very good one, might even be a joke to call it a firewall, but it might be blocking things like a ping). It just was not enabled. Maybe now that you've "rolled back" prior to SP2 the firewall is still enabled?

Anyway, seems like you can now focus on the networking question. Good luck going through the past posts, but there is plenty of information posted on that.