I wanted to connect a laptop I borrowed from work to the network at home. This needs dhcp if it's going to work in any reasonable way. So I installed a dhcp server on my debian box, easy with apt-get, and followed the instructions in The CTDP Linux User's Guide - DHCP and BOOTP and other places to get the thing configured.

However, the first time I try to start the server it won't work because it says the kernel isn't compiled with CONFIG_PACKET and CONFIG_FILTER set. True enough it isn't, and true enough this is my fault as this is a "custom" kernel I compiled last year. So, in order to attach a laptop to the network I have to recompile the kernel. OTOH, at least I've now got a more up to date kernel installed.