[strongSwan] IPtables -d or marking of ipsec traffic

[lux-integ]

Dear All

This is a Strongswan[IPsec]/IPtables question:-

Suppose I have a computer  with network-interfaces ppp+ and eth0 of fixed  
address say 172.16.0.1 ,

I have IPsec traffic coming through the ppp0 interface which I want to send to 
another network
to which eth0 is attached.  Suppose this other network sits on a 10.10.10.0 
subnet.  
In my IPtables script (for the computer with the ppp+ interface ), could I 
have a line such as the following  therein:-

iptables \
--append INPUT \
--match policy \
--pol ipsec \
--dir in \
--in-interface ppp0 \
--destination 10.10.10.10


though I do not have the 10.10.10.0  on this  machine ?


Alternatively If this is not possible is there a way to mark the packets  to 
identify their destination prior to sending them on?
Advice would be appreciated

Sincerely
luxInteg