CyberGuard SG300 User Manual page 102

Ensure Enable is checked and enter a descriptive GRE Tunnel Name for this tunnel.
Enter the address of the remote GRE endpoint in Remote Address, e.g. the Internet IP
address of a remote CyberGuard SG appliance.
Enter the address of the local GRE endpoint in Local Address. This is typically a free
address on your main LAN. If your LAN connection has an alias address, it may also be
a free address on the alias network.
Select a Firewall Class for the GRE interface, this setting is discussed in the Direct
Connection section towards the beginning of this chapter.
Click Finish. The GRE interface now appears in the main Network Setup table.
GRE over IPSec
The basic steps to set up GRE over IPSec are:
1. Use the same network for the primary IP addresses of the LAN interfaces at both
ends of the tunnel.
2. Assign unused alias IP addresses to the LAN interfaces at both ends of the
tunnel.
3. Create an IPSec tunnel between the alias IP addresses.
4. Create a GRE tunnel between the alias IP addresses.
5. Create bridges between the LAN interfaces and the GRE tunnel.
Network Setup
98