WebSocket proxy to telnet

I have used https://www.codeproject.com/Articles/63201/TelnetSocket in a .NET web application to develop a "proof-of-concept". The code makes use of the System.Net.Sockets.TcpClient .NET class to establish and manage a telnet connection. In my case, I wanted something simple to allow a an authenticated user, to execute a non-interactive shell program over telnet to change their password using an internally hosted web application (not accessible to the public Internet). This had already been done in PHP but I wanted something a bit different and something that integrated well with our existing .NET web application. The concept worked but I was never completely happy with the design approach. 

Cache Web Terminal does provide an interactive shell with intellisense but limitations mean you can't use it like you would use something like PuTTY and the current issue log presents quite a few challenges.