It is the ESP form of IPSec and, you are correct, it does not use a port. You would simply specify the protocol, e.g., iptables -t nat -I PREROUTING -d 129.37.0.111 -p 50 -j ACCEPT You may find it helpful to run through an iptables tutorial. I found Oskar Andreasson's (listed on the netfilter.org site) to be very helpful. There is also a slide show on using iptables in the training section on http://iscs.sourceforge.net Good luck - John On Fri, 2004-04-30 at 15:58, Rhaoni Chiu Pereira wrote: > Hi List, > > Aldo, thanks for the tip... I didn't know about the -I parameter... I still > have a doubt about a protocol type, I received a documentation of some rules > that I have to create in my firewall and it has a ESP(50) Protocol and no port > listed so I don't know how to make it using iptables! Does anyone know what is > this ESP(50) Protocol ? > > Atenciosamente, > > Rhaoni Chiu Pereira > SistÃmica Computadores > > Visite-nos na Web: http://sistemica.info > Fone/Fax : +55 51 3328 1122 > > > > Citando Aldo Lagana <ALagana@xxxxxxx>: > <snip> -- Open Source Development Corporation Financially Sustainable open source development http://www.opensourcedevelopmentcorp.com