IPsec and Multiple Subnets § Centipede Networks

08 Sep 2010

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	IPsec and Multiple Subnets

Solution If you need to route multiple IP subnets across an IPsec connection on pfSense or m0n0wall, there are two possible approaches.

1. CIDR-summarize subnets -- If all the subnets can be contained in one larger CIDR mask, you can use a single tunnel. An example of this would be the networks 10.0.0.0/24, 10.0.1.0/24, and 10.0.254.0/24 can all be summarized by 10.0.0.0/16. When used with IPsec, the network 10.0.0.0/16 will allow access to the many /24 networks within that network.

2. Parallel tunnels -- If it is not possible to CIDR summarize the subnets in use, for example 10.0.0.0/24 and 172.16.0.0/24, then parallel tunnels must be created. Each tunnel must have a different shared secret or they will not work.

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19 Jul 2007 08:27 AM