CLI and OS access help!

I am working on an embedded controller. In its released form, I want to give
a user access to an application which has a command line interface without
giving them access to the operating system. They telnet in and,
automatically, the application comes up. No login would be preferable. I
have no clue on how to accomplish this. A shove in the right direction would
be appreciated.

Thanks,

  • Ricardo