Blocked connections on LAN

[Tsunami]

I am wondering if the lights on my Netgear Router should be constantly flickering - even when I am not on the Internet or using files between computers.

I ask this because they have always done that but someone said they shouldn't. You see, I wonder if I am suffering a DOS attack.

The root of the problem is my XP computer is used as a file server. It's a peer-to-peer network, no domains or anything, but files I need to access from any computer, including my email data, are kept on it.

It runs fine for several hours. Then suddenly, it won't accept incoming connections from other machines on the network. It gets out to other machines OK and internet - including incoming remote connection - works well also.

A peek at the event log shows only one thing that it might be. It claims there is an attempted Denial of Service Attack because all work items have been used and some services have been shut down. I'm not convinced that the timing in the log concurs with when I notice the fault, but I could be wrong. Well I can see how a PC reacting to a suspected DOS attack would block access. Typical error mesage on other machines is either machine name is not known or it is not cofigured for file and printer sharing. So I guess (and it is only a guess) SMB just shuts port 445.

Once I reboot the machine everything is hunky-dorey again. I don't know if it is relevant, but I physically have to turn the machine off. If I try to shut it down, it hangs on the Windows is Shutting Down screen.

So back to the router lights... are they indicating another machine is possibly trying to send more data than it should? It could add up. But I haven't got the foggiest idea of how to deal with this.


This is what I have done to try to cure the problem...


I Changed the NIC
Reformatted the C:\ drive and resintalled everything


The other wired connection is to a machine that itself was the subject of a recent "format C:\" . (I think you can see how desperate I am now.)

Both machines have been scanned with a op-to-date trusted Internet Security Suite.


Technical details:

Router: Netgear WPN824
Machine with problem: Windows XP Pro SP3 1.5G mem
Other wired machine: Vista Ultimate SP1
Other wireless connections exist form time to time


All I want to do keep my server serving files! Can you help? I'd be ever so grateful!

Thanks

B

[cszeto]

If "peer-to-peer network" actually refers to peer-to-peer file sharing over the Internet, then the following thread may be directly related to your described situation.

http://forums.practicallynetworked.com/showthread.php?t=9420

[Tsunami]

No it's not to do with the internet.

This issue is to do with connecting from one computer to another on the same small LAN.

There are two ways of setting up a local area network. One is to have a domain, with a domain controller - usually on the server machine. This controls what the other computers (the clients) can access.

The second way - and this is the most common for home networks - is just to use a workgroup without a hierarchical server or domain controller. This is usually referred to as peer-to-peer. It is most definitely not the same as internet connected systems like kazaa or e-mule.

My set up is the latter! :-)

[Tsunami]

I did a bit more analysis. The target PC seems to be getting more packets in and out than the other PC.

So I disconnected everything (inclluding WAN uplink) from the router except the target PC and still there was lots of traffic in and out, lights flashing and so on. It seems it is trying to DOS itself! Is this sort of self-flagellation/masochism known (or normal) in the home networking world?

B

[cszeto]

Are you now adding additional information concerning a machine that is different than what you have initially referred to as the "server?" That is this new reference to "target PC?"