Seeking IPSec with NAT configuration examples

[Lucky Green]

Doc team,
I volunteered to update the IPSec section of the Handbook and am looking
for the following:

- any documentation not already mentioned in the Handbook's IPSec
chapter, the Daemon News article, or the FreeBSD Diary articles about
configuring IPSec on FreeBSD.

- configuration examples for using IPSec from behind a NAT or on a host
that acts as a NAT.

Thanks in advance,
--Lucky