Installing strongSwan on OpenBSD

In this tutorial, we'll go through the steps to install strongSwan on OpenBSD. strongSwan is a popular and widely-used VPN server software that is easy to install and configure.

Step 1: Update OpenBSD

Before we proceed with the installation, we need to ensure that our OpenBSD system is up to date. To do that, we'll run the following commands:

sudo syspatch
sudo pkg_add -Iu

These commands will update the system with the latest security patches and update the installed package.

Step 2: Install StrongSwan

Now, we can install strongSwan with the following command:

sudo pkg_add strongswan

The command will download and install strongSwan and all its dependencies.

Step 3: Configure StrongSwan

The StrongSwan configuration files are located in the directory /etc/ipsec.d/.

We'll create a new configuration file strongswan.conf with the following content by running the following command:

sudo nano /etc/ipsec.d/strongswan.conf

Add the following contents to the file:

config setup
  charondebug="ike 1, knl 1, cfg 0"  

conn ikev2-vpn  
  auto=add  
  compress=no  
  keyexchange=ikev2  
  fragmentation=yes  
  forceencaps=yes  

  ike=aes256-sha256-modp1024!  
  esp=aes256-sha256!  

  left=%any  
  [email protected]
  leftcert=example.com.crt  
  leftsendcert=always  
  leftsubnet=0.0.0.0/0  

  right=%any  
  rightid=%any  
  rightauth=eap-mschapv2  
  rightsendcert=never  
  rightsourceip=10.10.10.0/24  
  rightdns=8.8.8.8
  
  eap_identity=%identity 

Replace the /etc/ipsec.d/example.com.crt file with your own certificate file. After that, we'll create a new file /etc/ipsec.secrets to set up the authentication for IPsec by running the following command:

sudo nano /etc/ipsec.secrets

And then add the following line to the file:

: PSK "YourSharedSecret"

Replace the YourSharedSecret with a secure passphrase.

Step 4: Starting StrongSwan

Now that we have installed and configured strongSwan we can start the service by running the following command:

sudo rcctl start ipsec

To enable the service to start automatically on boot, we'll run the following command:

sudo rcctl enable ipsec

Conclusion

We now have a fully functional strongSwan VPN server running on our OpenBSD machine. By following the steps outlined in this tutorial, you should be able to create a secure and reliable VPN system that meets your needs.