I need to setup a VPN which is compatible with iOS devices (IPSec / L2TP / IKEv2, no PPTP please). My requirements are:
- Encrypted connection to a single server (with a critical application on it that should not be exposed to the internet)
- Only traffic to this specific server shall go through the VPN, traffic to other sites shall not be routed through the VPN
- Multiple clients should be able to connect to VPN to use the app on the server
- Those clients have dynamic IP-addresses
- They don't need to "see" each other but if they do it wouldn't be a problem
I've read a lot in the last days but the combinations and possibilities for VPNs seem to be endless. StrongSwan has some nice configuration examples, but none seem to match my requirements. I don't need a tunnel or bridge sites. A lot of tutorials show how to setup a L2TP over IPSec VPN to access the internet (e.g. from behind the great firewall) but that's not very helpful in my case.
- Do I need L2TP for this use-case?
- Can't I just use IPSec in transport mode?
- How would I setup IPSec authentication?
- Would IPSec in transport mode allow multiple clients?
- Can IPSec transport mode work with dynamic IPs of the clients?
Any hints or directions what to read next or what technologies to use are welcome. A configuration example even better :)