Windows network troubleshooting

I have a user who's writing a network server program, but his computer isn't accepting incoming connections. The program (as well as other network services, like a VNC server) works fine when initiating the connection from localhost, but not from any other computer on the network, including pings. Outgoing network connections work fine, including, to be pedantic, the replies, so it is accepting incoming data, just not unsolicited incoming data. I've turned off both the Windows firewall and the Symantec firewall that was installed on the computer with no change in symptoms (well, except that the Symantec firewall also prevents connections from localhost).

I've upgraded the drivers for the network cards. I've tested it with both the wired ethernet interface and the wireless interface with the same results. I've installed Wireshark (formerly Ethereal) and it doesn't even see the incoming packets, but it does see other packets, so Wireshark is working properly. When initiating a connection from a remote computer, the remote computer does get an arp reply, although I haven't made sure that it's receiving it from the computer in question directly.

The computer is connected to the same switch as all of the other computers that are working properly. I have tried it in different ports on that switch with no change in symptoms.

Does anyone have any idea what might be going on?

Yeah, you've done all the troubleshooting steps I would have done. That's a real stumper.

It sounds like something very firewall-like is configured on that computer, but you've done everything to make sure that's not the case. Including switching the ports on the router (because sometimes routers have per-port features that can do this kind of thing).

The only thing I can think of, and I'm sure this isn't the case because I know you're thorough, is that perhaps the Symantec firewall isn't as uninstalled as you think it is.

Wow, real stumper.

Since this is my bread and butter, I'm anxious to know the result and will watch this thread carefully.

What network card is it? If it is the onboard nvidia, check the firewall on that too.

Gah. There are network cards with built in hardware firewalls?

What's this world coming to?

Although, if you look at his description, he says he gets the same result with a wireless connection. So it's unlikely to be a hardware firewall built into a specific card.

Still sounds like something on the client side, some kind of software configuration or hidden software firewall.

Have you tried:

netsh int ip reset resetlog.txt

It's a common troubleshooting step that never works for me, but there's a first time for everything.

You're looking at the right network card, not the wireless card's IP? I'd put it on a disconnected hub and set manual IPs to just be sure you're controlling all the variables.

Matthew

I didn't uninstall Symantec Client Firewall before, just disabled it. I went to uninstall it now and the uninstaller encountered a fatal error. I rebooted and the firewall was all screwed up. I was then able to uninstall it. It still doesn't work, but the fact that the Symantec PoS software was so screwed up that it couldn't uninstall properly kind of points a finger at it. Tomorrow I'm going to try to reinstall it in the hopes that it will write over whatever is halfway installed now.

Also, not nVidia, Broadcom. And I tried the netsh thing to no avail, although it did claim to change some registry values.

I've seen odd and otherwise inexplicable XP networking problems recently and the cause was a bad MS patch (KB916089). I've also seen it reduce fast PCs to a crawl along with svchost crashes and 'soft lockups' where it hasn't actually locked up, you just need to be very patient.
Try running this fix - if it isn't needed it will tell you during the install procedure.

Quote:
I didn't uninstall Symantec Client Firewall before, just disabled it. I went to uninstall it now and the uninstaller encountered a fatal error. I rebooted and the firewall was all screwed up. I was then able to uninstall it. It still doesn't work, but the fact that the Symantec PoS software was so screwed up that it couldn't uninstall properly kind of points a finger at it. Tomorrow I'm going to try to reinstall it in the hopes that it will write over whatever is halfway installed now.

Ah, I've had that happen before, just disabling the Symantec firewall doesn't always work, and I have had those uninstall issues, but re-installing it normally fixes it up enough to uninstall it properly.

I hate symantec firewall, it is one of the biggest POS I've seen in a long time.