The mobile shell (mosh) uses SSH to establish an initial connection to a remote server and then goes on to exchange data (keystrokes and screen updates) using a custom protocol designed to hide latency and improve interactivity over slow and unreliable connections. In the existing implementation, this custom protocol runs only on UDP, which is not always available or convenient. Additionally, even though the mosh protocol was designed to run on UDP and is most efficient in this arrangement, there are still benefits that it could offer if executed over a TCP connection. The goal of this thesis is to extend the mosh client and server software to add a TCP network transport mode and add automatic fallback to TCP when UDP isn't available on the network.