IPsec: Setup OPNsense for IKEv2 EAP-RADIUS

EAP-RADIUS via IKEv2 is nearly the same as EAP-MSCHAPv2, but authentication is done against a Radius instance. We assume you have read the first part at IPsec: Setup Remote Access

Step 1 - Create Certificates

For EAP-RADIUS with IKEv2 you need to create a Root CA and a server certificate for your Firewall.

Go to System ‣ Trust ‣ Authorities and click Add. Give it a Descriptive Name and as Method choose Create internal Certificate Authority. Increase the Lifetime and fill in the fields matching your local values. Now go to System ‣ Trust ‣ Certificates and create a new certificate for the Firewall itself. Important is to change the Type to server. The Common Name can be the hostname of the Firewall and set as Alternative Name the FQDN your Firewall how it is known to the WAN side. This is most important as your VPN will drop when the FQDN does not match the ones of the certificate.

If you already have a CA roll out a server certificate and import the CA itself via System ‣ Trust ‣ Authorities and the certificate with the key in System ‣ Trust ‣ Certificates.

Step 2 - Setup Radius

If you already have a local Radius server, add a new client with the IP address of your Firewall, set a shared secret, go to OPNsense UI to System ‣ Access ‣ Servers and add a new instance:

Descriptive Name

Name

Give it a name

Type

Radius

This is what we want

Hostname or IP Address

Radius IP

Set the IP of your Radius server

Shared Secret

s3cureP4ssW0rd

Choose a secure password

When you do not have an own Radius instance just use the OPNsense plugin and follow this guide: FreeRADIUS

Step 3 - Mobile Clients

First we will need to setup the mobile clients network and authentication source. Go to VPN ‣ IPsec ‣ Mobile Clients

For our example will use the following settings:

IKE Extensions

Enable

checked

check to enable mobile clients

User Authentication

Nothing

As we use Radius, no need to select anything

Group Authentication

none

Leave on none

Virtual Address Pool

10.10.0.0/24

Enter the IP range for the remote clients

You can select other options, but we will leave them all unchecked for this example.

Save your settings and select Create Phase1 when it appears. Then enter the Mobile Client Phase 1 setting.

Step 4 - Phase 1 Mobile Clients

Phase 1 General information

Connection method

default

default is ‘Start on traffic’

Key Exchange version

V2

only V2 is supported for EAP-RADIUS

Internet Protocol

IPv4

Interface

WAN

choose the interface connected to the internet

Description

MobileIPsec

freely chosen description

Phase 1 proposal (Authentication)

Authentication method

EAP-RADIUS

This is the method we want here

My identifier

Distinguished Name

Set the FQDN you used within certificate

My Certificate

Certificate

Choose the certificate from dropdown list

Phase 1 proposal (Algorithms)

Encryption algorithm

AES

For our example we will use AES/256 bits

Hash algoritm

SHA1, SHA256

SHA1 and SHA256 for compatibility

DH key group

1024, 2048 bit

1024 and 2048 bit for compatibility

Lifetime

28800 sec

lifetime before renegotiation

Advanced Options are fine by default.

Save your settings.

Step 5 - Phase 2 Mobile Clients

Press the button that says ‘+ Show 0 Phase-2 entries’

../../_images/ipsec_s2s_vpn_p1a_show_p2.png

You will see an empty list:

../../_images/ipsec_s2s_vpn_p1a_p2_empty.png

Now press the + at the right of this list to add a Phase 2 entry.

General information

Mode

Tunnel IPv4

Select Tunnel mode

Description

MobileIPsecP2

Freely chosen description

Local Network

Local Network

LAN subnet

Route the local LAN subnet

Phase 2 proposal (SA/Key Exchange)

Protocol

ESP

Choose ESP for encryption

Encryption algorithms

AES / 256

For this example we use AES 256

Hash algorithms

SHA1, SHA256

Same as before, mix SHA1 and SHA256

PFS Key group

off

Most mobile systems do not support PFS in Phase2

Lifetime

3600 sec

Save your settings and Enable IPsec, Select:

../../_images/ipsec_s2s_vpn_p1a_enable.png

Note

If you already had IPsec enabled and added Road Warrior setup, it is important to restart the whole service via services widget in the upper right corner of IPSec pages or via System ‣ Diagnostics ‣ Services ‣ Strongswan since applying configuration only reloads it, but a restart also loads the required modules of strongSwan.

Step 6 - Add IPsec Users

Go to your RADIUS management console and start adding users! If you are using our FreeRADIUS plugin follow the official guide: FreeRADIUS