Since I was feeling adventurous, I decided to upgrade my vanilla kernel as well. The machine was running a vanilla 22.214.171.124 kernel which was becoming a little outdated. So I decided to take my chance compiling the most recent 126.96.36.199 kernel. Configuring and compiling was easy, but after a necessary reboot, iptables NAT and masquerading seemed b0rken. After googling a little bit, I discovered that the Netfilter people did a bit of refactoring in the modules and options necessary for NAT and masquerading. After enabling
-> Networking support (NET [=y])
-> Networking options
-> Network packet filtering framework (Netfilter) (NETFILTER
-> Core Netfilter Configuration
NF_CONNTRACK_ENABLED = [m]
the CONFIG_NF_NAT option appeared underneath "IP: Netfilter Configuration". After a 3rd compile and install, I've managed to get the configuration right and I am now running Debian Etch on a vanilla 188.8.131.52 kernel.
I guess it's nothing to be proud of ... but I am :)