[squid-users] Transparent Proxy on Linux - Problem

I have configured Squid 2.4 Stable6 to run on Red Hat Linux 7.3 (kernel 2.4.18)
as a transparent proxy for a LAN of about 50 PCs. The Linux box (Pentium4, 1.6
GHz, 512MB RAM) also acts as the gateway for the LAN using two ethernet
interfaces. I have used iptables to REDIRECT the outgoing port 80 tcp traffic to
port 8080 on which squid listens. The other (non web traffic) is routed using
SNAT. Everything worked fine for about 8-10 days but then suddenly a strange
problem occured. The client PCs stopped receiving any web pages. Checking the
squid status gave an ok response but the browsers on the client machines were
not receiving any web pages. The status bar on browsers showed " Web site
contacted. Waiting for Reply". However exisiting non-web connections (Yahoo, MSN
messengers, etc.) continued and worked fine. The service could not be restored
by restarting squid and the Linux box had to be rebooted to set things right.

Subsequently, this problem started occuring frequently (once a day, then twice
and now 3-4 times a day) and everytime we have to reboot the system to put
things in order. We have checked the squid and firewall configuration again and
again but have not been able to locate the reason for this problem. Checking the
squid access logs shows that when this problem occurs, the squid records the
requests in the access logs and using tcpdump on the external ethernet interface
I observed that some packets were going to the web sites requested by the
clients but there were no incoming packets from those web sites. However, ping
and traceroute work fine from the server as well as the client systems.

Has anyone faced a similar problem or suggest what could be done ? Please help.

TIA,

Manish
Received on Tue Sep 10 2002 - 11:26:58 MDT