cisco 1721 with proxy arp and vpn

Hi, I bought a cisco 1721 that I was using just for site to site vpn.

Now I want to take advantage of all the features of the equipment and
use it in the following configuration:


internet
|
|
<cisco1721-public address>----[vpn]------<remote site>
||
||
||
<firewall-public address>
|
|
|
[internal net - private address]

So, I need to be able to do the following:

1. Proxyarp a public address to my second firewall (i have some ip
addresses routed to me) Preferably filtering the requests.
2. Allow normal traffic to pass trough to the internet
3. Encrypt traffic destined to the remote site (requests coming from
internal net)
4. Receive traffic from the remote site in my internal net.


Do you think this is possible ? Do you have any goot starting
points/sample configurations ?

I got the vpn working ont the router but now i can't acces the net
from my second firewall.

Any help is appreciated.



ligiu