Tried running Ubuntu server 12.04 and CentOS 6.4 on a ol'Dell PowerEdge 2650 with 2xNICs. The machine is used as a proxy server with Squid 3.1 running Everything runs fine, except it runs into trouble from time to time. Every few hours or so, the machine simply refuses connection from some of the PC workstations. I can ping the machine from anywhere of my network, but no ssh and proxy... the machine simply times out those connections.
Some of the PCs connect to the machine again after issuing /etc/init.d/network restart... but some are still being refused.
/var/log/messages reveals nothing....
Any clues?
PS: I run a Dell PowerEdge 1750 with Fedora 5 installed as a proxy server as well... it never runs into the same problem... The two machines were bought almost 10 years ago.