。Linux 2.2.x H.323 masquerading module (Beware: I have a report that 2.2.0 fixes some problems, but also breaks some old configurations) http://www.coritel.it/coritel/download.html
。Linux netfilter (supports some H.323 packet filtering and NAT - as far as I understand you must apply the h323-conntrack-nat patch to your Linux kernel) http://www.netfilter.org/