RADIUS (Remote Authentication Dial-In User Service) is a protocol for checking a user's authentication and authorization information from a remote server. It is originally intended for authenticating dial-in users, but is also suitable for use with Secure Shell. In SSH Tectia, RADIUS is implemented as a submethod of Keyboard-Interactive authentication.
radius Keyboard-Interactive submethod requires one or more RADIUS servers to be configured in the
AuthKbdInt.RADIUS.NASIdentifier keyword defines the default NAS identifier to be used when talking to the RADIUS server.
AuthKbdInt.RADIUS.Server keyword defines one RADIUS server. The server address field is mandatory, other fields are optional. The address can be an IP address or a DNS name.
nasidentifier field overrides the default for this server, if specified.
The default file for the shared secret is
The default timeout is 23 seconds. This should be usually sufficient, but if the RADIUS server is expected to take a long time to process the authentication request, it can be lengthened. The servers are queried in the order they have been specified, and only one at a time. The minimum timeout is 7 seconds, and the timeout has a granularity of 8 seconds. The RADIUS server will always be queried for at least the number of seconds specified in the timeout parameter.
The supported RADIUS servers are the FreeRADIUS server and Microsoft IAS (Internet Authentication Service) server. The following sections contain advice on configuring them to interoperate with SSH Tectia Server.
FreeRADIUS Server Configuration
Configure the client (SSH Tectia Server) in
/etc/freeradius/clients.conf with the proper IP address and
nastype = other. The FreeRADIUS server can be instructed to check the users agains the system's main
passwd file with the following in
DEFAULT Auth-Type = System, Fall-Through = 1
/etc/freeradius/radiusd.conf, PAP must be configured to be available for authentication. See the FreeRADIUS documentation for further details.
IAS Server Configuration
For SSH Tectia Server to interoperate with Microsoft IAS, following must be done:
- Requiring Signature Attribute must be switched off in IAS.
- Dial-In must be allowed in the user's properties.
- PAP authentication must be allowed in IAS.
Note: SSH Communications Security does not provide technical support on how to configure RADIUS. Our support only covers SSH Tectia applications.