FortiGate Client VPN with static IP-Address (Framed-IP) and RADIUS

 Problem

Each user receives a fixed IP address for the VPN tunnel from the RADIUS server (in this case a FortiAuthenticator).

Solution

FortiAuthenticator / other RADIUS Server

For the RADIUS server, the RADIUS attribute "Framed-IP-Address" must be defined per user.

FortiAuthenticator



FortiGate

On FortiGate side we need the following configuration (expect the default Radius Configuration):
config vpn ssl web portal
    edit "tunnel-access"
        set ip-mode user-group
        set ip-pools "SSLVPN_TUNNEL_ADDR1"
    next
end
  • ip-mode:
    • user-group: Get IP-address from RADIUS Attribute (Framed-IP-Address)
    • range: The default option. Define to distribute IP-Addresses from the SSL-VPN IP Range
  • ip-pool: Which IP-Pool is used to distribute IP-address when ip-mode option is "range". If you choose "user-group" the static IP Address from the RADIUS Server has to be in that range.

Verify

diag debug enable
diag debug application fnbamd -1 <--- Responsible for authentication
diag debug application sslvpn -1
...
[1391] fnbamd_radius_auth_send-Compose RADIUS request
[1351] fnbamd_rad_dns_cb-172.16.51.12->172.16.51.12
[1329] __fnbamd_rad_send-Sent radius req to server 'radius_HQ-FAC': fd=14, IP=172.16.51.12(172.16.51.12:1812) code=1 id=11 len=119 user="john" using PAP
...
[1797] fnbamd_radius_auth_validate_pkt-RADIUS resp code 2
[320] extract_success_vsas-FORTINET attr, type 1, val Users_VPN
1414] fnbamd_auth_handle_radius_result-->Result for radius svr 'radius_HQ-FAC' 172.16.51.12(1) is 0
[1338] fnbamd_radius_group_match-Passed group matching
[333] fnbamd_framed_ip_add_ip-Added IP 10.212.134.207
...
[1277:Internet:34a]Auth successful for user john in group FAC-VPN
[1277:Internet:34a]user john got framed IP 10.212.134.207
 

Troubleshooting

Framed IP-Address not assigned to Client

Description

The defined static IP address is defined as "Framed-IP-Address" and FortiGate ignore it.
diag debug enable
diag debug application fnbamd -1
diag debug application sslvpn -1

...
[320] extract_success_vsas-FORTINET attr, type 1, val Users_VPN
[1414] fnbamd_auth_handle_radius_result-->Result for radius svr 'radius_HQ-FAC' 172.16.51.12(1) is 0
[1338] fnbamd_radius_group_match-Passed group matching
[333] fnbamd_framed_ip_add_ip-Added IP 10.212.134.207
...
[1277:Internet:352]Provided framed IP 10.212.134.207 is ignored.
...
[384] fnbamd_framed_ip_delete_ip-Deleted IP 10.212.134.207 for vfid 2
[2451] handle_req-Rcvd 7 req
[308] fnbamd_acct_start_START-Error getting radius server
...
[1277:Internet:355]tun dev (ssl.Internet) opened (40)
[1277:Internet:355]Will add auth policy for policy 2 for user john:FAC-VPN
[1277:Internet:355]Add auth logon for user john:FAC-VPN, matched group number 1
[1277:Internet:355]tunnel2_enter:1108 Framed IP is set to 10.212.134.200
[1277:Internet:355]fsv_associate_fd_to_ipaddr:1664 associate 10.212.134.200 to tun (ssl.Internet:40)

Solution

In that case often the Portal configuration is wrong. Double check the config vpn ssl web portal attribute ip-mode is set to user-group.




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