I have 3 pix 506 firewall to configure for 3 sites mesh topology. All the PIXes are sat behind the firewalls with NAT enable. each site have their own firewall. There are Sites A, B, and C. Site A is using Netscreen firewall with NAT, Site B is using Checkpoint with NAT, and Site C is using Linux IPTables firewall with NAT. All the PIXes 506 will site behind (inside) firewall, Is this possible? If yes, Do you have a sample for this configuration.