Public IP Address and Bridged Modems

In order to ensure that only one firewall is inspecting traffic and handling address translations on your network, your office firewall must receive a Public IP address on its WAN interface. 

This functionality may require the assistance of your internet service provider (ISP).

Identifying a private (non-public IP address) is fairly easy.  If your WAN has an IP address in one of the following IP blocks, it is not a Public address, and you should contact your ISP to help "Bridge" your Modem/Gateway device, allowing a Public IP address to be assigned to your firewall/router.

your router/firewall WAN IP ADDRESS
must not fall within these ranges:

10.0.0.0 - 10.255.255.255

172.16.0.0 - 172.31.255.255

192.168.0.0 - 192.168.255.255

 A "bridged" configuration ensures that the modem supplied by your internet service provider isn't behaving as an additional firewall on your network. This ensures traffic will be handled correctly and without delay. 

A "bridged" configuration ensures that the modem supplied by your internet service provider isn't behaving as an additional firewall on your network. This ensures traffic will be handled correctly and without delay. 

 A NON-bridged topology enables the modem to behave as an additional firewall and NAT device on the network. This extra firewall is at best superfluous and at worst can cause frustrating connection issues. In order to avoid these problems, it is best to place the modem into bridge mode and let the office's main router handle all firewall, NAT, and routing functions. 

A NON-bridged topology enables the modem to behave as an additional firewall and NAT device on the network. This extra firewall is at best superfluous and at worst can cause frustrating connection issues. In order to avoid these problems, it is best to place the modem into bridge mode and let the office's main router handle all firewall, NAT, and routing functions.