Wireless 802.1x EAP-TLS with computer authentication


In this recipe, you will configure and demonstrate wireless 802.1x EAP-TLS with computer authentication.

In the example, you will set up FortiAuthenticator as the Root CA and client certificate issuer. The FortiAuthenticator will authenticate without user interaction using the domain computer and client certificate (no username or password).

The example includes an Intel PROSet supplicant as well as a dynamically assigned group on a FortiWiFi using RADIUS attributes.

1. Active Directory prerequisites

Key considerations:

  • computers must exist in AD Groups that correspond with their VLAN
  • dNSHostName attribute for the username

2. Configuring the certificates

Go to Certificate Management > Certificate Authorities > Local CAs and create a new Root CA.
Go to Certificate Management > End Entities > Local Services and configure a certificate used for EAP-TLS.

Go to RADIUS Service > EAP and set up the EAP configuration.

If client certificates were not created by FortiAuthenticator, the 3rd-party server certificate would be uploaded on to FortiAuthenticator as a Trusted CA.

In this example, FortiAuthenticator creates the client certificates.

Go to Certificate Management > End Entities > Users and create a client certificate. The CN must match the full DNS name of the intended computer.

Export the PKCS#12 file and passphrase protect it.

The client certificate can be pushed out using GPO (Group Policy Object). Otherwise, it can be imported manually.

3. Manually importing the client certificate – Windows 7

Manual import can be completed using MMC as shown.

Open Command Prompt and type mmc and hit Enter.

On the File menu, click Add/Remove Snap In.

Once imported, the certificate should show up under Local Computer and not Current User.

Export the FortiAuthenticator Certificate and Import that under Trusted Root Certification Authorities (again under Certificates (Local Computer)).

4. Configuring the Intel PROSet Supplicant (Windows 7)

The supplicant will automatically select the certificate associated with the computer, based on the configuration shown.

Under General Settings, set Operating Mode to Network [Infrastructure] – Connect to WiFi networks and/or the Internet.

Under Security Settings, be sure to enable Use the certificate issued to this computer.

With this configuration, no user interaction is required for 802.1x EAP-TLS, on startup or attempting to connect to the WiFi, the authentication and authorization process will be transparent to the user.

5. Configuring the FortiAuthenticator AD Server

Go to Authentication > Remote Auth. Servers > LDAP and create a new AD server.

Ensure that Username attribute matches the entry in the AD configuration in Step 1.

Go to Authentication > User Management > Realms and create a new realm for these users.

6. Configuring the user group

Go to Authentication > User Management > User Groups and create a new user group with the RADIUS attributes shown.

7. Configuring remote user sync rules

Go to Authentication > User Management > Remote User Sync Rules and configure a new Remote LDAP User Synchronization Rule.

Go to Authentication > User Management > Remote Users and check to see if the sync rule worked.

8. Configuring the FortiAuthenticator RADIUS client

Go to Authentication > RADIUS Service > Clients and create a RADIUS client to bring the configuration together on the FortiAuthenticator.

9. Configuring the FortiWiFi

Go to User & Device > Authentication > RADIUS Servers and set the FortiAuthenticator as the RADIUS server for the FortiWiFi.
Go to WiFi & Switch Controller > WiFi Network > SSID and configure the WiFi SSID interface.
Go to System > Network > Interfaces and configure a software switch combining the physical and WiFi interfaces.

10. Results

The authentication flow should initiate as soon as the wired computer starts up (while connected to the domain).

Using tcpdump, FortiAuthenticator shows receipt of an Incoming Authentication Request (tcpdump host -nnvvXs):

01:09:34.674298 IP (tos Ox0, ttl 64, id 40954, offset 0, flags [none], proto UDP (17), length 212) > [udp sum ok] RADIUS, length: 184 
    Access-Request (1), id: 0x76, Authenticator: 4b859401ddb6c0fb95261e99fc8ef66a 
      User-Name Attribute (1), length: 23, Value: host/leno.fortiad.net 
        0x0000: 686f 7374 2f6c 656e 6f2e 666f 7274 6961 
        0x0010: 642e 6e65 74
      NAS-IP-Address Attribute (4), length: 6, Value: 
        0x0000: 0000 0000 
      NAS-Port Attribute (5), length: 6, Value: 0 
        0x0000: 0000 0000 
      Called-Station-Id Attribute (30), length: 28, Value: 88-DC-96-27-72-68:fortinet
        0x0000: 3838 2d44 432d 3936 2d32 372d 3732 2d36 
        0x0010: 423a 666f 7274 696e 6574 
      Calling-Station-Id Attribute (31), length: 19, Value: 6C-88-14-C6-3D-58
        0x0000: 3643 2d38 382d 3134 2d43 362d 3344 2d35
        0x0010: 38
      Framed-MTU Attribute (12), length: 6, Value: 1400
        0x0000: 0000 0578
      NAS-Port-Type Attribute (61), length: 6, Value: Wireless - IEEE 802.11 
        0x0000: 0000 0013
      Connect-Info Attribute (77), length: 24, Value: CONNECT 11Mbps 802.11b 
        0x0000: 434f 4e4e 4543 5420 3131 4d62 7073 2038 
        0x0010: 3032 2e31 3162 

Continuing with tcpdump, Access-Challenge is issued from FortiAuthenticator to the FortiWiFi:

01:09:34.679881 IP (tos Ox0, ttl 64, id 58896, offset 0, flags [none], proto UDP (17), length 108) > [bad udp cksum 0xl8a3 -> 0xbe6al) RADIUS, length: 80 
    Access-Challenge (11), id: 0x76, Authenticator: a4c016a41e6a0f46c17da49ff813bd6e 
      EAP-Message Attribute (79), length: 24, Value: .. 
        0x0000: 0101 0016 0410 f23e 13dd 795e 18fa SddS
        0x0010: 3e83 cb34 a99c
      Message-Authenticator Attribute (80), length: 18, Value:
        0x0000: eac9 2509 cbec 6895 804a deac 5de7 d6f8
      State Attribute (24), length: 18, value: *...* ....... 
        0x0000: 2af7 lbfd 2af6 lfb9 8db9 f1f8 20ad 9cd4 

The next 14 messages are Challenge->Request EAP transactions between the FortiAuthenticator and the FortiWiFi.

Access-Accept message with RADIUS attributes are returned to the FortiWiFi:

01:09:36.517763 IP (tos Ox0, ttl 64, id 58903, offset 0, flags (none), proto UDP (17), length 225) > (bad udp cksum 0x1918 0x1f60!) RADIUS, length: 197 
    Access-Accept (2), id: Ox7d, Authenticator: 989626b68773ac50c060d8306287984a 
      Vendor-Specific Attribute (26), length: 58, Value: Vendor: Microsoft (311) 
        Vendor Attribute: 17, Length: 50, Value: ?...e....NA=E.5.9..y........Q ^R=i..!j .........
        0x0000: 0000 0137 1134 80e3 aefl 65e0 1383 c34e
        0x0010: 413d 4Sbd 350d 39be ac79 04b8 90fa 1551
        0x0020: a4b7 10d3 09b6 f902 5e52 3d69 b3b4 216a
        0x0030: b48f 0ef2 0c08 9cd0
      Vendor-Specific Attribute (26), length: 58, Value: Vendor: Microsoft (311)
        Vendor Attribute: 16, Length: 50, Value: z
        0x0000: 0000 0137 1034 8883 7a9b bllb 9488 f181
        0x0010: d179 29ba 7538 lleb 8311 3c22 1b62 9176
        0x0020: d0be f763 4617 670c d8ca 8659 7a14 dl2c
        0x0030: 8064 5955 942b ccla 
      EAP-Message Attribute (79), length: 6, Value: .. 
        0x0000: 0307 0004 
      Message-Authenticator Attribute (80), length: 18, Value: ....>k....? ...( 
        0x0000: 9aec 02c0 3e6b af8e defb 8020 e50b 0728 
      User-Name Attribute (1), length: 23, Value: host/leno.fortiad.net
        0x0000: 686f 7374 2f6c 656e 6f2e 666f 7274 6961 
        0x0010: 642e 6e65 74 Vendor-Specific Attribute (26), length: 14, Value: Vendor: Fortinet (12356)
      Vendor Attribute: 1, Length: 6, Value: VLAN10
        0x0000: 0000 3044 0108 564c 414e 3130 

Post-authentication DHCP transaction is picked up by FortiAuthenticator (tcpdump continued):

01:09:39.765661 IP (tos 0x0, ttl 64, id 15537, offset 0, flags [none], proto UDP (17), length 300) > [udp sum ok] BOOTP/DHCP, Reply, length 272, hops 2, xid Ox5a6b3f9e, Flags [none] (0x0000)
    Client-Ethernet-Address 6c:88:14:c6:3d:58
    Vendor-rfc1048 Extensions
      Magic Cookie 0x63825363
      DHCP-Message Option 53, length 1: ACK
      Server-ID Option 54, length 4:
      Default-Gateway Option 3, length 4:
      Domain-Name-Server Option 6, length 8:,
      Time-Zone Option 2, length 4: 3600 

On the FortiAuthenticator, go to Logging > Log Access > Logs to verify the device authentication.

The Debug Log (at https://<fac-ip>/debug/radius) should also confirm successful authentication.

On the FortiWifi, go to WiFi & Switch Controller > Monitor > Client Monitor and note that the Group is the RADIUS attribute sent from FortiAuthenticator. Any Firewall policy using that Group will now be enabled for the user.

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Note that to view certificates in the local machine store, you must be in the Administrator role.
If the Authentication tab is not visible under your LAN properties then you may need to configure the Wired AutoConfig service to automatically start.
This rule automatically imports computers in the AD Group VLAN10 into the FortiAuthenticator User Group VLAN10.
Users/computers should be visible under Remote Users. Certificate bindings must be manually completed.
Certificate CN has to match the Remote User Computer Name.