Configuration examples

Below are the most common type of IPsec configurations people use. While written for libreswan, the instructions will work for openswan as well unless specifically noted.

VPN server to VPN server configurations

host to host VPN

subnet to subnet VPN

host to host VPN with PSK

subnet to subnet VPN with PSK

route-based VPN using VTI

EoIP shared ethernet LAN using IPsec

subnet to subnet using NAT

VPN server for VPN client configurations

VPN server for remote clients using IKEv2

VPN server for remote clients using IKEv1 XAUTH with Certificates

VPN server for remote clients using IKEv1 XAUTH with PSK

VPN server for remote clients using IKEv1 with L2TP

libreswan as client to a Cisco (ASA or VPN3000) server

IKEv1 XAUTH with Google-Authenticator One Time Passwords (OTP)

IKEv1 XAUTH with FreeOTP and FreeIPA

subnet extrusion

VPN configurations to connect to cloud providers

Using libreswan in OpenStack as VPNaaS

High Availability / Failover VPN in AWS using libreswan

Microsoft Azure configuration

OpenShift Cloud Encryption with libreswan 

Misc items

Using Apache to serve PKCS#12 format .p12 files