does ipchains support stateful inspection and dynamic filtering in kernel 2.2.18?

no, it doesn't

whats about kernel 2.4.x and iptables? I found nothing on the web which describes the different filter functions on different network layers. Could anyone give me a short description which functions are implemented in kernels 2.2.1x and 2.4.x, or give me a link about these topics?

Can't tell you. But take a look at www.opensourcefirewall.org. This might be what you're after.

Thanks

u're welcome, Philipp