Address: The name or address of your RADIUS server.
Listen Port: The port your RADIUS server listens on (usually 1812).
Secret Key: This is the password shared between IMAuth and your RADIUS server. Before IMAuth can connect, you will need to open your RADIUS server's config file or control panel and add a new RADIUS Client. This involves creating a Shared Secret, which you should then enter into this field.
Security Level: This box determines what type of encryption IMAuth will use when communicating with the RADIUS server. This should match one of the types your RADIUS server is configured to accept. The strongest security is provided by MS-CHAPv2 encryption, although this is a Microsoft proprietary standard, and may not be supported on all RADIUS servers. Other encryption types are provided for compatibility.