[Openswan Users] l2tp firewall kernel 26

Jacco de Leeuw jacco2 at dds.nl
Tue Jun 28 16:40:31 CEST 2005

> where I can to find a how-to about firewall (based on iptables) configuration
> for to enable l2tp traffic on box with kernel 2.6 (Fedora Core 3) and
> openswan 2.3.1 

Always remember to use nmap and scan for open UDP ports once the firewall
is in place. Preferably scan from a client on the Internet, not from the
server itself.

E.g. nmap -sU The L2TP daemon (UDP port 1701) should then
be listed as filtered. The only open ports should be UDP 500 (IKE) and
optionally UDP 4500 (NAT-T).

Jacco de Leeuw                         mailto:jacco2 at dds.nl
Zaandam, The Netherlands           http://www.jacco2.dds.nl

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