We have two sites, one linux based, the other windows based which we would like to connect permently over VPN.
Does anyone know which linux VPN software is best for this? (I'm using PPTP on windows atm, but will change to IPSec once I understand what I am doing)
The primary reason to to run an offsite backup (I think we will use bacula for this).
what about using openvpn? open source, available for windows and linux.
and easy to set up... will save you some headache that ipsec can bring.
for backups - maybe you can just use ssh encapsulation - and do not set anything up at the windows side. i have quite good experience with rdiff-backup, but i'm using it only under linux [ although it has windows version as well ].
I don't know baculla, but if it does support this, maybe you could just have it create an ssh connection using key-based authentication when it is time for the backup. You can also use ssh to create a vpn tunnel, but I would recommend that, it is more ad-hoc.
I think if that is possible, you might find it to be a simpler solution. Not sure if this is the best answer for you or not, but I think it is worth looking into.
IPCop can be a solution. It's linux-based, you just need a simple machine to act as your gateway. It supports site-to-site VPN and roadwarrior VPN (user to site). I think that part is based off OpenVPN -- it definitely generates the .ovpn file for the user part.