[lug] Linux boxes drop off the net? Router problem?

[Sebastian Sobolewski]

>I also just ran a test that Sebastian Sobolewski suggested yesterday. I
>logged into an external shell account and pinged our Linux boxes to find a
>"dead" one (which answers another question somebody asked -- they don't all
>die at the same time). Once I found a dead one, I pinged from that box to an
>outside address and I was immediately able to ping the machine from my
>external shell account.

Ok we're one step closer.  I'm assuming you are using dumb hubs. 
(unmanaged) which points the fault at either the 3com switch or the 
router.  Some routers/switches use the ARP protocol to keep track of 
machines attached to them.  I'm curious if perhaps the linux boxes are not 
responding to ARP messages, which is causing them to drop of the 
network.  Switches hubs ARE intelligent enough to add an entry into their 
ARP table when they see a packet coming from a machine attached to them. 
(This would explain why the machine shows back up after a ping out from it)

         You mentioned that you had several security packages installed on 
all of the linux machines. Perhaps one of them is filtering ARP messages?

-Sebastian
Sebastian Sobolewski