Remote Authentication and Dial-In User Service (RADIUS) is a broadly supported client-server protocol that provides centralized authentication, authorization, and accounting functions. RADIUS clients are built into gateways that allow access to networks such a VPN server, network access server (NAS), and a network switch or firewall that uses authentication.
RADIUS servers use UDP packets to communicate with the RADIUS clients on the network to authenticate users before allowing them access to the network, authorize access to resources by appropriate users, and account or bill for those resources that are used. RADIUS servers are currently defined by RFC 2865 (RADIUS) and RFC 2866 (RADIUS Accounting), and listen on either UDP ports 1812 (authentication) and 1813 (accounting), or ports 1645 (authentication) and 1646 (accounting) requests. RADIUS servers exist for all major operating systems.
The RADIUS server must be configured to accept the FortiGate as a client so is can use the authentication and accounting functions of the RADIUS server.
RADIUS authentication with a FortiGate requires the following:
- Configuring one or more RADIUS server profiles on the FortiGate.
- Assigning the RADIUS server profile to a user or user group.
- Applying the user or user group to a firewall policy.
RADIUS authentication can be applied to many FortiGate functions, such as firewall authentication, SSL and IPsec VPNs, administrator profiles, ZTNA, explicit proxy, wireless, 802.1X, and more.
The RADIUS server uses a shared secret key with MD5 hashing to encrypt information passed between RADIUS servers and clients. Typically, only user credentials are encrypted. Additional security can be configured through IPsec tunnels by placing the RADIUS server behind another VPN gateway.
The following topics provide more information about RADIUS servers:
- Using multiple RADIUS servers
- Configuring RADIUS SSO authentication
- RSA ACE (SecurID) servers
- Support for Okta RADIUS attributes filter-Id and class
- Sending multiple RADIUS attribute values in a single RADIUS Access-Request
- Traffic shaping based on dynamic RADIUS VSAs