Unable to pass traffic over ipsec tunnel originating from local host

[Aaron Nichols <adnichols_(_at_)_gmail_(_dot_)_com>]

All,
    I have the following fairly basic configuration:

OpenBSD 3.5 host connecting to SBC via a PPPoE based DSL connection.
This host acts as the gateway for a small network and has an ipsec VPN
to a remote location. The VPN works fine in the sense that all hosts
on the LAN are able to communicate to the remote site. The one thing
that does not work however, is that traffic originating from the
OpenBSD host itself destined for hosts on the other side of the VPN
(10.0.0.0/8) seems to be routed out the WAN interface (tun0). This
isn't entirely unexpected, but I'm wondering how this can be worked
around? At this point, since the traffic originates from the tun0
interface, which has an SBC assigned public address, it doesn't match
the local network definition in isakmpd and thus, isn't passed over
the VPN.

The basic problem I'm trying to solve is that I need to be able to
test connectivity from this host over the VPN to insure that it's
functional and if not - kick in some countermeasures. Without the
ability to send/receive traffic directly from this host, short of
setting up a 2nd host on the lan to do the monitoring (which isn't
really an option), I don't have a way of doing this.

I'm glad to post the related config info if someone cares to see - but
I'd rather not spam the list with all that just yet incase someone has
already worked with this issue and knows it either works or does not.

Thanks,
Aaron