I'm trying to install a third-party VPN client on a Linux system and I'm having a problem. Hopefully one of you kernel gurus out there can help me figure it out.

There's a kernel module integral to the system, but when I try to insert it, I get the error "unresolved symbol nf_register_hook". The obvious response to this is "Build Packet Filtering into your kernel, you ninny," but I have. The system.map claims that it's in there, but don't know any way to actually verify it. I did change the version string just to make sure I was booting the right kernel, and I was. In building the kernel, I made clean, dep, clean, bzImage, modules, and modules_install and then put .../arch/i386/boot/bzImage in the right place. I don't see what I'm doing wrong. Maybe I need some kernel option turned on other than just CONFIG_NETFILTER.

This is on a Gentoo 2.4.26.