How to render a remote ncurses console?

I wanna write a remote console, working like a telnet server. User is able to use telnet to log into the server, then write some commands to do some works.

A good example for this is the console of router os. What I'm confusing right now is, I can accept user's input, do someting then print some texts back, but I wanna use ncurses to make the console has more features(such as "cmd auto-complete", syntax color...), so how can I do that? Because the console is in user side, if the server calls ncurses APIs it'll just change stuffs on server...

Maybe this is a stupid question but I'm really newbie on this. Any suggestions are appreciated.