Since I've been doing no netfilter/iptables related work recently, I've announced that the three day training is going to be the last one, at least for the time being.
Though stressful as usual (have you ever talked/presented straight 8 hours on three consecutive days?) it was a quite joyful experience. Apart from the netfilter/iptables workshop earlier this year, the only contact with my former much-beloved project in 2007.
However, the training made me realize how outdated all the existing documentation (and even my own training material) is. Basically everything was written in the early 2.4.x days - and much has changed ever since.
There's all the nf_conntrack / nf_nat related changes, as well as the x_tables transition, which can cause many subtle errors due to old scripts expecting different kernel module names, etc.
None of the HOWTO's or similar documents talk about the conntrack userspace program yet, there's no documentation (and no release) for ulogd2, etc.
So I'll really try to sit down and find some time to improve some of those areas. It yet remains to be seen if I can actually make it. But I feel there's a real gap to be filled...