XAuth

Configure IPsec/XAuth VPN Clients
Configure IPsec/XAuth VPN Clients
Following these steps allow you to configure your Android, iOS, MacOS, and Linux machine using IPsec/XAuth (Cisco IPsec) VPN.
IPsec (L2TP, XAuth, IKEv2) VPN Server Auto Setup
IPsec (L2TP, XAuth, IKEv2) VPN Server Auto Setup
A few years ago, I've found this gem which allow us to set up our own IPsec VPN server with L2TP, XAuth and IKEv2 on Ubuntu, Debian, RHEL, and CentOS.