I've configured OpenVPN on CentOS7 to access my office network and it's working fine too. For authentication, it queries an LDAP server and it requires third-party software "OpenVPN client" in windows.
The only drawback that I face is that it doesn't work on android neither in iOS and also requires third-party. Now I don't want to use third-party for VPN access as there is already VPN option on all Windows as well as in Android, iOS. I want some suggestion for my VPN.
I've read about strongswan, openswan, libreswan, IPsecVPN but couldn't decide which one will be better in my case as they all suggest that some changes need to be done on windows registry which I don't want to do as there are maximum windows client in our office and It will be impossible to access individually and make some changes in their registry. Giving priority to windows client there shouldn't be any changes required and they can simply access through default VPN option.
I need a VPN server which can be run on CentOS 7 and it should be accessible by default VPN option on windows, android and iOS without any changes need to be done. If this can be possible than please suggest me. I want to run it on CentOS 7 and total clients will be around 250.