More configuration options

[tbartelmess]

I've created a fork of the repo, to add more configuration options and make certificate authentication the default. I understand that the goal here was to be simple so you probably don't want to merge it. I've added a link at the top of my Readme that links to your repo, and I just want to make sure you are ok with the attribution I gave you.

https://github.com/tbartelmess/docker-ikev2-vpn-server/tree/certificate-auth

[tbartelmess]

However on second thought maybe it makes sense to merge those two repos and just have different branches for different configuration templates.

[gaomd]

Thanks for the copyright notice & attribution.

I really wish we have certificate auth option since this kind of questions arise in the Issues quite often.

I will try to understand you branch and consider your auth branch suggestion.

However, there are some commits looks very helpful already, could tbartelmess@0056fa1 replace the apt-get install ndppd option? If so, a pull request is welcomed :)