Get and install strongSwan on the IPsec RA VPN client.

1. Update your system packages.

   $ dnf --refresh distro-sync

2. Add the packages that you need to run IPsec/IKEv2.

   $ dnf install epel-release  # Only necessary for CENTOS
   $ dnf install strongswan     # /etc/strongswan/
   $ rpm -qi strongswan

   The details will look something like this:

   Name : strongswan
   Version : 5.7.2
   Release : 1.el7
   Architecture: x86_64
   Install Date: Thu 05 Dec 2019 18:21:19 UTC
   ...