I'm a newbie in OpenVPN and the related questions, I'm googling for several days without positive answer.
I have several linux-based devices located in my town that collects data and sends it for me. I also need to be able to execute some commands on them. I've decided to connect all of them into one virtual private network over the Internet. I've chosen to use OpenVPN to do it. I have no problems with building OpenVPN.
After some work, I've successfully connected all devices into network. All devices use PKI to validate/authenticate themselves. The problem: Devices doesn't have real-time clock, so after turning off the power, we have incorrect time on device and they can't connect to my VPN server.
I found that time synchronization is required for PKI authentication.
In this mailing list users suggest to use static keys. Ok, I found an article on how to make this, but as I see there is one disadvantage: Limited scalability -- one client, one server. As I understand I can't use one vpn server for multiple devices.
Can anyone tell me how to solve the problem? Maybe there is some other authentication solution for OpenVPN which is independent from time synchronization?
P.S. I can't change time setting on that devices.
P.P.S. Thanks in advance and sorry for my terrible English.