I am having trouble setting up a local web cache and filtering system using squid and dansguardian.
It works perfectly when the browser is configured to use the proxy box's ip (192.168.1.2) but I cannot create a working transparent setup - using iptables on the default gateway to redirect all port 80 traffic (except traffic from the proxy) to the proxy box.
I am using the mangle iptable to mark these packets, and I have an ip rule that routes them using a separate routing table, with only one entry, a default route to the proxy box.
How can I trouble shoot this? I guess my question is twofold, how can I follow packets of interest through iptables to see what happens to them, and what am I doing wrong in regards to my proxy setup?