IPsec Remote Access VPN Example Using IKEv2 with EAP-MSCHAPv2

IKEv2 Server Configuration

There are several components to the server configuration for mobile clients:

• Creating a certificate structure for the VPN

• Configuring the IPsec Mobile Client settings

• Creating the phase 1 and phase 2 for the client connection

• Adding IPsec firewall rules.

• Create user credentials for the VPN

IKEv2 Certificate Structure

Tip

A certificate created by the ACME package (ACME package) will be natively trusted by many clients and can be used in place of a manually created private CA and server certificate.

Windows clients may not accept an ACME certificate as it may lack a property for IKE in the extended key usage attributes. This check can be disabled, however. See Disable EKU Check.

Create a Certificate Authority

If a suitable Certificate Authority (CA) is not present in the certificate manager, creating one is the first task:

• Navigate to System > Certificates

• Click Add to create a new certificate authority

• Set the options as follows:

  Descriptive Name:

  Mobile IPsec CA

  Method:

  Create an internal Certificate Authority

  Randomize Serial:

  Checked

  Common Name:

  mobile-ipsec-ca

• Leave the rest of the fields at their default values or adjust to suit local preferences

• Click Save

Create a Server Certificate

Warning

Follow these directions exactly, paying close attention to how the server certificate is created at each step. If any one part is incorrect, some or all clients may fail to connect.

• Navigate to System > Certificates, Certificates tab

• Click Add to create a new certificate

• Set the options as follows:

  Method:

  Create an internal Certificate

  Descriptive Name:

  IKEv2 Server

  Certificate Authority:

  Mobile IPsec CA

  Common Name:

  The hostname of the firewall as it exists in DNS, e.g. vpn.example.com.

  If clients will connect by IP address, place the IP address here instead.

  Certificate Type:

  Server Certificate

  Alternative Names:

  Type:

  IP Address

  Value:

  The WAN IP address of the firewall , e.g. 198.51.100.3

  Add more Alternative Names as needed for additional hostnames or IP addresses on the firewall that clients may use to connect.

• Click Save

Mobile Client Settings

The next step is to choose an IP address range to use for mobile clients. Ensure that IP addresses do not overlap any existing network.

Warning

The IP addresses used by mobile clients must differ from those in use at the site hosting the mobile tunnel as well as the LAN from which the client will be connecting.

This example uses 10.3.200.0/24, but it can be any unused subnet.

• Navigate to VPN > IPsec, Mobile Clients tab

• Enable IPsec:

  Enable IPsec Mobile Client Support:

  Checked

  

  Enable Mobile IPsec Clients

• Set the authentication options as follows:

  User Authentication:

  Local Database as seen in Figure Mobile Clients Authentication.

  This setting is not needed for EAP-MSCHAPv2, but it must have something selected.

  Tip

  RADIUS servers defined in the User Manager (User Management and Authentication) can be selected here for authenticating users when using EAP-RADIUS.

  

  Mobile Clients Authentication

• Set the Client Configuration options

  These settings may be pushed to the client, such as the client IP address and DNS servers. These options are shown in Figure Mobile Clients Pushed Settings. Support for these options varies between clients, but is common and well-supported in most current operating systems.

  Virtual Address Pool:

  Checked, 10.3.200.0/24

  Virtual IPv6 Address Pool:

  Checked, 2001:db8:1:df01::/64

  Network List:

  Checked

  DNS Default Domain:

  Checked, example.com

  Split DNS:

  Checked, example.com example.org

  DNS Servers:

  Checked, 10.3.0.1

  

  Mobile Clients Pushed Settings

  See also

  For additional information these options work, see Client Configuration.

• Click Save

• Click Create Phase 1 at the top of the screen if it appears

  

  Mobile Clients Phase 1 Creation Prompt

Phase 1

The phase 1 configuration for mobile clients must be configured as follows:

Description:

Mobile IPsec or another suitable description

Key Exchange Version:

IKEv2

Internet Protocol:

IPv4 for this example as it only uses an IPv4 WAN

Interface:

WAN

Authentication Method:

EAP-MSCHAPv2

My identifier:

Choose Fully Qualified Domain Name from the drop-down list and then

enter the hostname of the firewall, vpn.example.com.

Warning

This must match the value in the server certificate.

Peer Identifier:

Any

My Certificate:

Choose the IPsec server certificate created earlier

Encryption Algorithm:

Add multiple combinations of encryption, hash, and DH options to accommodate various clients with different requirements. Click Add Algorithm to add more entries. They should be added with the most secure and preferred options first.

A good starting set of options is:

• Algorithm AES256-GCM, Hash SHA256, DH Group 16

• Algorithm AES256-GCM, Hash SHA256, DH Group 2

• Algorithm AES 256, Hash SHA256, DH Group 14

• Algorithm AES 256, Hash SHA1, DH Group 14

Life Time:

28800

MOBIKE:

Set to Enable to allow clients to roam between IP addresses, otherwise set to Disable.

• Click Save

Phase 2

• Click Show Phase 2 Entries to expand the list of mobile phase 2 entries

• Click Add P2 to add a new mobile phase 2.

  Description:

  Mobile IPv4

  Mode:

  Tunnel IPv4

  Local Network:

  Set to LAN subnet or another local network.

  Tip

  To tunnel all traffic over the VPN, use Network and enter 0.0.0.0 with a mask of 0

  Protocol:

  ESP

  Encryption algorithms:

  Set to combinations of options which will be accepted by all possible clients. A good starting set is:

  • AES, 128

  • AES128-GCM, 128

  • AES256-GCM, 128

  Hash algorithms:

  Similar to the algorithm, select all options required by clients:

  SHA256, SHA384, SHA512

  PFS:

  14 (2048 bit)

  Warning

  Apple iOS does not support PFS in phase 2 when configuring a VPN manually as demonstrated in Configuring IPsec IKEv2 Remote Access VPN Clients on iOS. Most other clients require PFS to be enabled. The best practice is to use a VPN profile from the Apple Configurator or IPsec Export Package which can support the use of PFS rather than creating a VPN connection manually.

  Lifetime:

  3600

• Add another phase 2 entry but this time for IPv6. The settings are identical to the previous entry with the following changes:

  Description:

  Mobile IPv6

  Mode:

  Tunnel IPv6

  Local Network:

  LAN subnet as before or use the network value :: with a mask of 0 to tunnel all traffic.

• Click Save

• Click Apply changes

The tunnel setup for mobile clients is complete.

Mobile IPsec User Creation

The next step is to add users for use by EAP-MSCHAPv2.

• Navigate to VPN > IPsec, Pre-Shared Keys tab

• Click Add to add a new key

• Configure the options as follows:

  Identifier:

  The username for the client.

  This can be expressed in multiple ways, such as an e-mail address like jimp@example.com

  Secret Type:

  EAP

  Pre-Shared Key:

  The password for the client, for example abc123

• Click Save

• Repeat as many times as needed for additional VPN users.

A complete user is shown in Figure Mobile IPsec User.

Mobile IPsec User

Firewall Rules

As with the static site-to-site tunnels, mobile tunnels also require firewall rules at Firewall > Rules on the IPsec tab. In this instance the source of the traffic would be the subnet chosen for the mobile clients and the destination will be the LAN network, or any if tunneling all traffic.

See also

For more details, IPsec and firewall rules.

Client Configuration

Each mobile client device needs a VPN instance or client configured. In some cases a third-party IPsec client may be required. There are many different IPsec clients available for use, some free, and some commercial applications. With IKEv2, as used in this example, many operating systems have native VPN clients and do not need extra software.

Common clients are covered at Configuring IPsec IKEv2 Remote Access VPN Clients.