Xrsh is designed to allow you to start an X client on a remote machine with the window displayed on the current server's $DISPLAY. It has many options that give you the ability to propagate environment variables (including DISPLAY) to the remote system and works with various types of X server access control including xauth and xhost. Xrlogin opens a local xterm window and runs rlogin (or optionally telnet) to connect to a remote machine.