About Dynamic IP Addresses on the External Interface
If you want your Firebox external interface to use a dynamic IP address, you must configure your Firebox in routed mode when you use the Quick Setup Wizard.
If you select DHCP, your Firebox connects to the DHCP server controlled by your Internet service provider (ISP) to get its IP address, gateway, and netmask. This server can also give DNS server information for your Firebox. If it does not give you that information, you must add it manually to your configuration. If necessary, you can change the IP addresses that your ISP gives you.
You also can use PPPoE. As with DHCP, the Firebox makes a PPPoE protocol connection to the PPPoE server of your ISP. This connection automatically configures your IP address, gateway, and netmask.
If you use PPPoE on the external interface, you must have the PPP user name and password when you configure your network. If your ISP gives you a domain name to use, type your user name in the format [email protected] when you use the Quick Setup Wizard.
A static IP address is necessary for the Firebox to use some functions. When you configure the Firebox to receive dynamic IP addresses, the device cannot use these functions:
- Drop-in mode
- 1-to-1 NAT on an external interface
- Mobile VPN with PPTP
If your ISP uses a PPPoE connection to give a static IP address, the Firebox allows you to enable Mobile VPN with PPTP because the IP address is static.