HTML Client for X11 SSH Forwarding – Options and Setup

This is my solution (thanks for the xpra pointer). It goes like this:

1. Assumes same bashrc locally and remote
2. Use tmux-ssh to attach to the remote site. It takes normal ssh(1) args like -p and -u. It basically calls tmux-x-attach() on the remote site
3. tmux-x-attach() starts an xpra server if none is running, then attaches to the running xpra server and submits to tmux-attach()
4. tmux-attach() will either
   1. start a new tmux session if none exists
   2. attach to the (single) running tmux instance
   3. prompt for which of multiple tmux sessions to attach to
5. when detaching, we fall back into tmux-x-attach, which detaches from xpra before the ssh session terminates
6. An attempt (tput init) is made to clean up the terminal if tmux was detached from within eg. vim

From .bashrc

  tmux-x-attach() {
     ps -f -u $USER | grep -v grep | grep -q 'xpra start' || xpra start :9
     xpra attach :9 --opengl=no > /tmp/xpra-attach.log 2>&1 &
     DISPLAY=:9 tmux-attach "$@"
     xpra detach :9
  }

  tmux-attach() {
     case $(tmux list-sessions 2>/dev/null | wc -l) in
        0) tmux ;;
        1) tmux attach ;;
        *)
           tmux list-sessions 
           read -n 1 -p "Select command: " N < /dev/tty > /dev/tty;
           tmux attach -t $N
           ;;
     esac
  }
  tmux-ssh() { ssh "$@" -A -X -t 'PS1=tmux-ssh- ; . ~/.bashrc ; tmux-x-attach'; tput init; }

You're probably seeing the xauth timeout that ForwardX11Trusted no sets. You can change the length of the timeout with ForwardX11Timeout, but unfortunately you can't set that very long—it will crash the X server (or maybe just error out in newer Xorgs). See the question Disable ForwardX11Timeout without ForwardX11Trusted in OpenSSH Client?

You can set ForwardX11Trusted yes or use ssh -Y to disable the timeout entirely, though.