Some PAM modules and authentication mechanisms are case sensitive, while others are not. Usernames in the ThinLinc client are case sensitive by default, however this behaviour can be changed. See LOWERCASE_LOGIN_NAME in Configuration Parameters Used by the ThinLinc Client for details.

The SSH server should be configured to allow “keyboard-interactive” authentication for full functionality. The “password” authentication method does not allow multiple interactive prompts which is required for things such as password changes during login.