WIKI webhosting

In today's digital world, securing data on the internet is critically important. One effective solution for securing online communication and data is the use of a VPN (Virtual Private Network), specifically IKEv2 with IPSec technology, implemented through the open-source tool StrongSwan. This article provides a detailed guide on setting up and using StrongSwan to establish a secure IKEv2 VPN with IPSec.

What is StrongSwan?

StrongSwan is open-source software that implements IPSec protocols for securing network connections. It supports a wide range of cryptographic protocols and authentication methods, making it an ideal choice for creating a secure VPN.

Prerequisites

• Server with Linux installed (Ubuntu/Debian preferred)
• Valid domain name pointing to the server
• Open ports 500 and 4500 in the network firewall

Installing StrongSwan

1. Update the system and install StrongSwan:

   sudo apt-get update && sudo apt-get upgrade -y
   sudo apt-get install strongswan strongswan-pki libstrongswan-standard-plugins
   ​

Configuring IKEv2 with IPSec

Generating Certificates

2. Create directory structure for certificates:

   mkdir -p ~/pki/{cacerts,certs,private}
   chmod 700 ~/pki
   

3. Generate root CA certificate:

   ipsec pki --gen --type rsa --size 4096 --outform pem > ~/pki/private/ca-key.pem
   ipsec pki --self --ca --lifetime 3650 --in ~/pki/private/ca-key.pem --type rsa --dn "CN=VPN CA" --outform pem > ~/pki/cacerts/ca-cert.pem
   

4. Generate server certificate:

   ipsec pki --gen --type rsa --size 4096 --outform pem > ~/pki/private/server-key.pem
   ipsec pki --pub --in ~/pki/private/server-key.pem --type rsa | ipsec pki --issue --lifetime 1825 --cacert ~/pki/cacerts/ca-cert.pem --cakey ~/pki/private/ca-key.pem --dn "CN=vpn.example.com" --san vpn.example.com --flag serverAuth --flag ikeIntermediate --outform pem > ~/pki/certs/server-cert.pem
   

 

Configuring StrongSwan

5. Configure ipsec.conf:

   • Edit the file /etc/ipsec.conf and add configuration for your VPN server.
   • Example configuration:

   • config setup
       charondebug="ike 2, knl 2, cfg 2, net 2, esp 2, dmn 2,  mgr 2"
     
     conn %default
       ikelifetime=60m
       keylife=20m
       rekeymargin=3m
       keyingtries=1
       keyexchange=ikev2
       authby=secret
       left=%any
       [email protected]
       leftcert=server-cert.pem
       leftsendcert=always
       leftsubnet=0.0.0.0/0
       right=%any
       rightdns=8.8.8.8,8.8.4.4
       rightsourceip=10.10.10.0/24
     
     conn IPSec-IKEv2
       auto=add
     ​

 

 

• Configure ipsec.secrets:

  • Add the server's private key and the PSK (Pre-Shared Key) to /etc/ipsec.secrets.

 

 

Starting and Testing the VPN

7. Restart StrongSwan and test the connection:

   sudo ipsec restart
   sudo ipsec status
   ​

By using StrongSwan for IKEv2 VPN with IPSec, you gain a strong layer of security for your internet connection. With advanced configuration and flexibility, you can build a robust VPN solution tailored to the specific needs of your organization or personal use.