Virus, modem, and switch

What happened
----------------

One computer in the network was infected with 26 viruses.

A few hours later the SMC router-switch went down (all lights were off
except power indicater).

Next day I plugged in a D-Link router switch; it worked.

Later a domain I was working on could be "ping", but could not accessed
through HTTP protocol. A little bit later, it could not be "ping".

I worked on another domain as well; this domain resides in the same web
server as the above mentioned domain. The domain was accessible all this
time.

And then an about hour later, I could reached the second domain.

Question
---------

Is this the sign of a virus infection ?

Thanks.

On Sun, 10 Oct 2010 16:07:44 +0800, SL wrote:
> What happened
> ----------------
>
> One computer in the network was infected with 26 viruses.
>
> Later a domain I was working on could be "ping", but could not accessed
> through HTTP protocol. A little bit later, it could not be "ping".
>
> Question
> ---------
>
> Is this the sign of a virus infection ?

You already indicated machine on lan had malware. So answer has to be yes.

Malware can poison DNS cache, modify router, change routing, feed your
system bogus dhcp packets, ....

All going to depend on your setup. Telling your linux box to use
public dns ip like 208.67.222.222 208.67.220.220 from http://opendns.org/
will help in the DNS problem area.

Setting your ip as static will prevent a malware dhcp server from
feeding your system bogus dhcp packets.

In your case, I would have powered down router and PCs, power up
router/modem, factory reset router, power up linux box, change
password in router/modem and disable Plug-n-Play in router.
Change linux box to static ip about 100 address away from normally
assigned address, set opnedns servers, reboot and verify you can get
to the Internet. Change all passwords, login, mail,...

Unplug windows system from internet, power up, save any data files,
Insert windows cd, reboot, wipe system, install, plugin internet
cable, get all updates, reboot, scan backed up data files, install
data files.