To configure a site-to-site IPSec VPN tunnel on pfSense for remote access, you will need to follow these steps:
Log in to the pfSense web interface and navigate to VPN > IPSec.
Click the "Add P1" button to add a new phase 1 configuration.
In the "General Information" section, enter a descriptive name for the VPN connection and select "Site to Site" as the "Remote Gateway Type".
In the "Phase 1 Proposal" section, select the encryption and authentication algorithms that you want to use for the VPN connection.
In the "Phase 1 Advanced Configuration" section, enter the remote gateway's IP address or hostname in the "Remote Gateway" field.
Click the "Save" button to save the phase 1 configuration.
Click the "Add P2" button to add a new phase 2 configuration.
In the "General Information" section, enter a descriptive name for the VPN connection and select the phase 1 configuration that you created in the previous steps.
In the "Phase 2 Proposal" section, select the encryption and authentication algorithms that you want to use for the VPN connection.
In the "Phase 2 Advanced Configuration" section, enter the local network and remote network information for the VPN connection.
Click the "Save" button to save the phase 2 configuration.
Click the "Apply Changes" button to apply the VPN configuration.
That's it! Your site-to-site IPSec VPN tunnel should now be configured and ready for use.