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.

Installed that fix; no joy.

In regards to Symantec: I tried to uninstall, failed. Uninstalled successfully after a reboot, reinstalled, then tried to uninstall again and failed.

I'm really pretty sure at this point that the Symantec firewall installation got badly hosed. Unless someone can suggest something else, I'm probably going to have to reinstall. That three laptop Windows reinstallations in a week.

Whee. :/

Check this page out: http://basconotw.mvps.org/SymRem.htm

Don't know if it will help, but it couldn't make things worse

I tried using the official Symantec remover app, which completed without error, but did not solve the problem. Maybe I'll look through those remaining instructions.

Stuipd question, his system isn't set up with any of the following things, is he?

- A proxy server

- A proxy client software package

- A replacement TCP/IP stack (as AOL was once well known for doing)

?

There does not appear to be anything along those lines installed on the computer.

Hm. Real stumper.

Wonder if you can deinstall TCP/IP altogether and reinstall it, and if that'd even do any good.

Of course, at this point, I would have already dusted off and nuked the site from orbit. But there's a certain amount of academic curiosity here, and I'm sure that's the same reason you haven't done the same already.

If in doubt, reinstall is the final and universal Windows troubleshooting step...

Well, the problem is that the computer functions 100% fine except for this one thing, and I already have a number of laptops to reinstall, which all coincidentally died this week, all with different problems. I don't really want to get a third person to transfer all his data over to a new computer.

I know it's pretty far fetched, but at this point it sounds like all the common issues have been checked. Have you checked the mac and ip addresses on the network for a duplicate?

When you look at "ipconfig /all" what is the node type? I've had a similiar problem where I had to remove a key from the registry.

My user's not here today, but:

Uh, WTF is "Node Type"?

My understanding is that the node type is related to DNS, and I don't believe Bitt is describing a DNS problem. Still, worth looking at. Also, another link.

I've had a similiar problem with my home network. Not knowing what the offending computer has been used for I thought it was something worthing checking. If I unplug my workstation from the router and plug it directly into the wildblue modem the registry will be over written. When I plug the workstation back into the router I can no longer reach it from any of my other computers but I can reach them from it. I have to go into the registry and remove a key. After rebooting the computer works fine. Sorry about the lack of detail on the registry key but I have managed to hose my workstation this morning. It is in the local machine/something something/ netbt/ permissions section. Of course last night I erased my workstation backup in order to play around with backing up my new Mac.