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linksys router with comcast cable modem on 2 xp machines

Posted on 2003-11-12
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Last Modified: 2013-11-29

I have the following setup working but its become flaky recently (wasnt so flaky before 1 week)

cable modem (comcast) to a linksys BEFSR41 4 port router with 1.44.2z firmware (dec 2002. I read somewhere this is the stable version)
I recall using the ethernet address of the router to register with the comcast modem (so it thinks that it is dealing with the router as a computer).

Recently I have been losing pings on the XP pro machines connected to the router (to the 192.168.1.1 itself.. it becomes hideously long or unreachable which is bizarre)

it resolves after a shutdown and reboot (pings again) on one of the machines.
on the other one a simple router power cycle helps (no need to reboot)
 
not sure why this behavior has surfaced recently..

my router settings are as follows:

domain name: comcast.net

for some reason the LAN IP address and the WAN connection type fields have almost the same ethernet MAC addresses..
just differs by ONE on the very last digit.  not sure what to make of this. These ethernet addresses are in small font.

none of the virus stuff is enabled

in the advanced tabs, the MAC addr clone seems to have the same address at the WAN connection type ethernet address on the opening page

working mode is as a gateway

I am not blocking WAN requests etc. as sometimes I use a VPN (right now I am not using VPN)

I wonder if my settings are correct. (well they have to be to some extent as my setup works till the recent flakiness)

Heh: I couldnt post it as I lost the connection on this machine again. no ping from router

a shutdown and reboot will enable me to post this

update:  I havent yet shutdown.. I powered on the router and it gets back the ping for the other XP machine (but not the one I work on)

something happens pretty soon and I lose pings to the router on both machines (and of course the net as well)

then when I power up the router the second machine gets back its ping and net access
the first one (which I am working on) is still finding the router unreachable.. until the reboot after which it will last for 10 minutes or so


If my prediction is correct a log off wont help matters. lets see.
the cold reboot doesnt help at all. now for shutdown and reboot

ok the shutdown works.. before i lose this let me post it.

summary:

Both XP pro machines lose ping to router which is connected to cable modem
one of them is revived when the router is powercycled
for other one a warm reboot is needed and the connection after this does not last long.

is it a NIC problem in the warm reboot machine? or is the router very old (which it is)

I can access the interface for the modem itself usine 192.168.100.1 and it contains a MAC address that seems unfamiliar (under PC connectivity). I assume this could be the MAC address for the modem itself.


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Question by:nsriram
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Expert Comment

by:lrmoore
ID: 9736375
This sounds suspiciously like a Welchia worm infection or MSBlaster infection

http://securityresponse.symantec.com/avcenter/venc/data/w32.welchia.worm.removal.tool.html
http://securityresponse.symantec.com/avcenter/venc/data/w32.blaster.worm.removal.tool.html

Symantec online scanner
http://securityresponse.symantec.com/
(click on the Check for security risks icon)

Use Trend Housecall online scanner
http://housecall.trendmicro.com/

click the "scan now" link
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Expert Comment

by:mcmurrick
ID: 9736735
Sounds like a bad router to me. Especially if cycling the power on the  router makes a difference.

 However what you have mentioned about reboots sounds like you intentionally rebooted so it does not sound related to welchia or blaster.

It would be nice to have a third machine running to verify that your problem was not virus related. If you have access to another machine such as a friends laptop plug it in to your home network and if it exhibits the same issue it is router related.

Or you could kind of create a virtual third machine by loading a static OS on CD such as Knoppix. If your machine has 128 MB of RAM or more you could boot to knoppix which creates the linux swap and home directory in RAM rather than your hard drive and autodetects and configures most hardware at boot. Once booted you have a all the normal tools to test your network or recover data. As well as if you are able to replicate the problem on both machines running the knoppix distro it would verifyThe knoppix distro of Debian linux has been a lifesaver for me. Knoppix mirrors can be found at linuxiso.org . Hope this helps...
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Author Comment

by:nsriram
ID: 9736777

ok.. one machine is fine and has net access.

I really dont think its a router issue

the second one is flaky (the one I am using now)
however I am on safe-mode with networking mode right now on the second machine

so it seems to be ok with safemode with networking (at least so far)

can I scan a machine when I am on safe mode with networking.. I had scanned it earlier with AVG etc. and didnt find anything..

maybe its welchia or msblast... I do get these spams with attachments which I delete with annoying regularity but thats unrelated I suppose

Yeah.. I should get knoppix on a cd :-)


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Expert Comment

by:mcmurrick
ID: 9736790
Hey if that doesn't work it doesnt hurt to remove the TCP protocol and reinstall to see if that makes a difference on the unstable machine.
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Accepted Solution

by:
mcmurrick earned 500 total points
ID: 9736814
I really doubt that it is Welchia or MS Blast. It could be as simple as a number of things but this does not sound like a virus.

Items to check:
1. If you have an additional network port on your router try moving the cable from your flaky machine to the other port. Or utilizing the good machines port to rule out a bad connection to the router.
2. Verify that pins have not been bent on the flaky machines NIC visually inspect or see if light pressure pushing the cable in to the back of the NIC makes a connectivity difference. If so replace the Cable or NIC whichever seems to be the issue.
3. If feasable use a known good cable to the router to your machine to verify that it is not the network cable causing your problem.

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Author Comment

by:nsriram
ID: 9736818

well even the safe mode loses the ping after 5 minutes. the other machine is ok (and I am using it now).

will try removing and reinstalling tcp

the troublesome machine sometimes does a hard hang and I think its related to the network issue..

NIC is reported to be fine by xp.. but one never knows.

yes.. I was rebooting myself to get the connectivity to the router
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Author Comment

by:nsriram
ID: 9736918
to clarify further

right now both PCs are up and connected.. but within 5-10 minutes the troublesome one may lose it

I will investigate router, cable and NIC issues as well as I have a laptop also..
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Author Comment

by:nsriram
ID: 9737383
as a closing comment.. this is what I did to make it stable (so far)

 make the router settings as restrictive as possible

and remove a 1394 card (digital video) that I wasnt using and somehow shows up as a network card (are these?) and blew some hot air on the network card (using a hair dryer) and chanted some magical incantations

its stable so far.. and a laptop also seems to work ok with the router...
 
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