VPN (racoon) problem if client is behind NAT router

Eric J. Feldhusen efeldhusen.lists at gmail.com
Mon Jul 30 18:40:34 UTC 2007

Anderson Oliveira da Silva wrote:
> Hello folks,
> I´ve been trying to set up racoon in order to enable a VPN service to
> the following scenario: client behind NAT router (D-Link 624 Router) and
> server not behind NAT router. Client is WinXP default IPSec/L2TP client.
> Server is running racoon/l2tpd. Everything works fine if the client is
> not behind the NAT router. But l2tpd does not answer if the client is
> behind the NAT router.
> Here is the output presented by tcpdump in the server side when client
> is behind the NAT router:
> Does anyone know why the packets transported by ESP are not forwarded to
> l2tpd?

I don't have a racoon/l2tpd server setup, but I was looking into it and
I recall the racoon configuration requiring a flag, telling racoon it
was behind a NAT.  Sorry I can't remember the exact flag, but I haven't
set it up yet.


Eric Feldhusen
Network Administrator    http://www.remc1.org
eric at remc1.org
PO Box 270              (906) 482-4520  x239
809 Hecla St            (906) 482-5031 fax
Hancock, MI  49930      (906) 370 6202 mobile

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