ASA Local ID Set IPSEC - How?

[Snooty42]

Hello,

I have a IPSEC VPN from a 5505 device connecting to HeadOffice.

On the ASA5505 I need to know how I can set the local id to a IP address of my choice.

ASA5505=DHCP=Router=PublicIP===Internet==PublicIP==HeadOffice

The Headoffice IPSEC is set to connect to my public IP + PSK

The problem is that my ASA5505 is behind a router so
my localId presented to the VPN is currently not my public IP.

As a result the VPN tunnel will not establish and errors with
Invalid ID Info ( 18 ) , Invalid Message ID ( 9 )

I need to work out how to set the LocalID of the ASA unit to my PublicIP address e.g 85.190.142.68

Any insight appreciated.

Thanks
Pete