Juniper tends to have pretty good documentation in their knowledgebase, on how to configure equipment for different situations. I recently had to setup a VPN between a Juniper SSG-140 (at HQ) and a remote Cisco PIX. Going to Juniper's knowledgebase, you would most likely come across the article: http://kb.juniper.net/KB4147 . This article describes setting up a "route-based" VPN between the two devices. I believe these directions would work if you were trying to connect one subnet on each end.

I had the need to install FreeSWAN on an old RedHat Linux 7.3 machine. While most people's initial reaction would be to upgrade the system, we all know this is not always an option.

I initially tried to do a simple "rpmbuild --rebuild..." but that did not do the trick. I would get "unresolved symbol..." errors. However, I finally found a way to get the kernel module to compile correctly.