[Openswan Users] Connections from LAN ok, but problems with modem

[José Julio Hernández Fernández]

Hi all,

I've got a VPN server (SuSE 9.0, kernel 2.6.6, OpenSWAN 2.1.2), with
Linux and Windows clients running fine. I've been using "e.bootis"
client on Windows, and I'm testing L2TP client included on W2K and
WinXP.

All tests have been made from LANs with private addresses. NAT-Ted
communications work fine. But now I've found a great problem: when
trying to connect to VPN server with a modem, from the same PCs that
worked ok in LAN, I can't establish IPsec session. ¿Does it make sense?
¿Is it a matter of NAT (not needed, because ISP provides a public IP)?
¿MTU size? ¿Has anyone an idea? ¿Have you seen a similar scenario? Any
message would be really appreciated, because information on the Net
about this issue is not enough for me to fix it...

Thanks in advance, JJ.