How to Set Up IPsec-based VPN with Strongswan on CentOS/RHEL 8

TecMint: strongSwan is an open-source, multi-platform, modern and complete IPsec-based VPN solution for Linux that provides full support for Internet Key Exchange (both IKEv1 and IKEv2) to establish security associations (SA) between two peers. It is full-featured, modular by design and offers dozens of plugins that enhance the core functionality.