Openswan

wikipedia:Openswan IPsec linux implementation

ipsec rereadsecrets
(no output) 

net.ipv4.ip_forward = 1
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.all.send_redirects = 0

systemctl strongswan-starter status

See also

• VPN: IPsec (Openswan), OpenVPN, Forticlient, GlobalProtect (PAN-OS), WireGuard (Linux Kernel), Tailscale, PulseSecure, WebVPN, SoftEther, ESP, IKE, AWS VPN, Zerotier, VPN client, Pritunl, GCP Cloud VPN, Mesh virtual private network, Mullvad