>We are looking to build a simple little Virtual Private Network between
>two buildings. It isn't supposed to be anything too heavy duty. Just a
>little project. We were wondering if there was public domain software
>(Especially for Linux) that we could do it with. What we want to do is :
The problem is that encryption is classified as a munition by most
governments, and therefore export controlled. It is difficult to get
strong crypto in public domain software (Phil Zimmerman ran into
several years worth of hassles when PGP escaped into the `net).
Likely, you can find a 40-bit DES freeware if you look around.
However, this is weak enough that people are routinely cracking this
via simple exhaustive key-space searches.
I'd suggest that you do without or get a commercial product that
supplies strong crypto, meaning Triple-DES or IDEA. Going with 40-bit
DES will more or less give you the illusion of security, rather than