We have number of CentOS/RHEL5 servers in datacenter, which are secured with border firewall (basically, only http/https and ssh are allowed). Sometimes me (as systems administrator) & selected developers are required to connect to some local services.
Currently we are doing this by ssh proxying or by mapping some external ip:ports to internal one (to protocols which are supports encryption). But it's not always convenient to use ssh and I'd like to remove all custom firewall rules (for security reasons). So I need to use some vpn solution. OpenVPN seems to be fine and I think I'll stick with it. But I'm wondering if there are some (may be better?) alternatives. Requirements are:
- Allow simulations connections for 2-5 users.
- Users should have separate accounts (username/password and/or cert)
- Total number of users: I believe not more than 10
- It should work perfectly under Windows XP/Vista/7 and any Linux
- Server should work perfectly on one of our CentOS servers
- I need to have ability to remove user account/invalidate cert
- It should be opensource or at least free
- (optional) user should have ability to re-issue cert and/or change password without my attention.