5.5.1 PPP Half Bridge
When the PPP Half Bridge is enabled the BIPAC 5100S becomes invisible. The DHCP server will duplicate the WAN IP address from the ISP to the local client PC. Only one PC is able to access the Internet using half bridge mode.
Half bridge mode can only be used when a single IP address has been assigned by the ISP, it is not suitable for services that provide multiple IP addresses. Half bridge mode is used when the use of NAT or NAPT is not desired and there is a single computer attached to the BIPAC 5100S ADSL Gateway.
5.5.2 When to use Half Bridge mode
When using a separate firewall that will be protecting the network, half bridge mode will allow the firewall to appear on the internet using the publicly accessible IP address assigned by the ISP. This configuration will allow the dedicated firewall to have full control of the inbound and outbound traffic and is the intended purpose for this mode.
Some applications that embed the IP address of the computer in the data are not compatible with NAT or NAPT and so the computer requires a real public IP address. However the number of applications that are not compatible with NAT/NAPT are reducing as developers address the issues. Before deciding to use half bridge mode please check to see if the application can be made to work using the virtual server port forwarding feature on the BIPAC 5100S. Using NAT/NAPT is preferable as it provides the first line of defence against attack from hackers/crackers and allows the connection of more than one computer.
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