[strongSwan] Which source IP@ for egress IKEv2 packets

[Martin Willi]

Hi,

> As we plan to implement source routing on our product, we would like to
> know if charon daemon is filling the source IP address of egress IKE
> packets with the local outer IP address ("left" parameter of the
> ipsec.conf file) and if the egress IKE IP packets go through linux
> routing stack.

If a left= address is explicitly specified, charon passes the source
address via sendmsg() to the kernel (at least on Linux, or any platform
that supports IP_PKTINFO or IP_SENDSRCADDR sendmsg() options).

Even if left= is unspecified, charon reuses the source address where it
received the IKE packet, or does a lookup in the routing tables.

So I'd yes, the source address is set when outgoing IKE packets are
routed in the kernel.

Regards
Martin