Installing StrongSwan on Ubuntu 18.04

StrongSwan is an open-source IPsec-based VPN solution for Linux. It implements the IPsec protocol suite, providing secure communication over insecure networks. StrongSwan allows users to establish a VPN tunnel between two devices, enabling secure remote access to networks or bypassing network restrictions.

Step 1: Update the system

Before installing StrongSwan, it is recommended to update the system packages:

sudo apt update
sudo apt upgrade

Step 2: Install StrongSwan

To install StrongSwan, use the following command:

sudo apt install strongswan

Step 3: Configure StrongSwan

After the installation, you need to configure StrongSwan to set up your VPN connections. The main configuration file is located at /etc/ipsec.conf. Open the file using a text editor:

sudo nano /etc/ipsec.conf

You can then define your VPN connection parameters, such as authentication method, encryption algorithms, and remote gateway information. Save the file when finished.

Step 4: Configure IPsec Secrets

In the same directory, create or edit the /etc/ipsec.secrets file with the user credentials and private keys. This file should be secured with specific permissions:

sudo nano /etc/ipsec.secrets
sudo chmod 600 /etc/ipsec.secrets

Here's an example of how to structure the file:

: PSK "your_pre_shared_key"
your_username : EAP "your_password"

Step 5: Enable IP forwarding

To allow IP forwarding, edit the /etc/sysctl.conf file using the command:

sudo nano /etc/sysctl.conf

Uncomment the line net.ipv4.ip_forward=1 to enable IP forwarding. Then save and exit.

Apply the changes using:

sudo sysctl -p

Step 6: Restart services

Restart the StrongSwan service to apply the configurations:

sudo systemctl restart strongswan

You have now successfully installed StrongSwan on Ubuntu 18.04. You can proceed to configure specific VPN connections according to your needs.