[strongSwan] How to do NAT before ESP? having trouble

Andreas Steffen andreas.steffen at strongswan.org
Sun Jul 22 22:43:05 CEST 2012

Hi Mark,

here is an IKEv2 example where the clients are NAT-ed to the
virtual IP of the gateway:


In order to automatically insert the NAT iptables rules you need
a special updown scripts I wrote a couple of years ago:


Best regards


On 07/22/2012 08:53 AM, Mark M wrote:
> Hi,
> I am running a mobile road warrior client with strongSwan connecting to
> a strongSwan gateway. The mobile client has two interfaces, one for an
> inside subnet and one for the WAN connection. Behind my mobile client on
> the LAN side, I have another host that I would like to connect through
> the mobile client using NAT. Kinda like if i used my laptop as a mobile
> hotspot for other clients to connect to and all their connections are
> sent to my strongSwan gateway. I tried to setup NAT using iptables with
> the inside interface and the outside interface and it does not work. I
> looked around on old emails and i think what i am looking to do is it
> NAT before ESP. I need to NAT my LAN client to the virtual IP address or
> the outside WAN interface before it gets sent down the tunnel to my
> strongSwan gateway. I was looking at the older emails about the updown
> scripts but I can't find one for IKEv2 and charon. I also read that
> there was work being done on a leftnat parameter but work on it was halted.
> Is there any way I can do this?
> Thanks
> Mark-

Andreas Steffen                         andreas.steffen at strongswan.org
strongSwan - the Linux VPN Solution!                www.strongswan.org
Institute for Internet Technologies and Applications
University of Applied Sciences Rapperswil
CH-8640 Rapperswil (Switzerland)

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