com.mosh.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>EnvironmentVariables</key>
    <dict>
      <key>PATH</key>
      <string>/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin</string>
    </dict>
    <key>Label</key>
    <string>com.mosh</string>
    <key>Program</key>
    <string>/Users/Shared/.startup/mosh.sh</string>
    <key>RunAtLoad</key>
    <true/>
    <key>KeepAlive</key>
      <dict>
        <key>SuccessfulExit</key>
	<true/>
      </dict>
    <key>StandardOutPath</key>
    <string>/tmp/startup.stdout</string>
    <key>StandardErrorPath</key>
    <string>/tmp/startup.stderr</string>
    <key>UserName</key>
    <string>admin</string>
    <key>GroupName</key>
    <string>admin</string>
    <key>InitGroups</key>
    <true/>
  </dict>
</plist>

install.sh

#!/bin/sh

# create correct file permissions
sudo chmod 644 "/path/to/mosh.sh"
sudo chmod 644 "/path/to/com.mosh.plist"

# create correct file ownerships
sudo chown root:wheel "/path/to/mosh.sh"
sudo chown root:wheel "/path/to/com.mosh.plist"

# create target destination
mkdir -p "/Users/Shared/.startup"

# put files in correct locations for LaunchDaemon
sudo ln -s "${DOTFILES}/path/to/mosh.sh" "/Users/Shared/.startup/mosh.sh"
sudo ln -s "${DOTFILES}/path/to/com.mosh.plist" "/Library/LaunchDaemons/com.mosh.plist"

# add mosh launch daemon
sudo launchctl load -w "/Library/LaunchDaemons/com.mosh.plist"

mosh.sh

#!/bin/bash

# wrap in function to allow for local variables
fix_mosh_server() {

  # local variables for convenience
  local fw='/usr/libexec/ApplicationFirewall/socketfilterfw'
  local mosh_sym="$(which mosh-server)"
  local mosh_abs="$(greadlink -f $mosh_sym)"

  # temporarily shut firewall off
  sudo "$fw" --setglobalstate off

  # add symlinked location to firewall
  sudo "$fw" --add "$mosh_sym"
  sudo "$fw" --unblockapp "$mosh_sym"

  # add symlinked location to firewall
  sudo "$fw" --add "$mosh_abs"
  sudo "$fw" --unblockapp "$mosh_abs"

  # re-enable firewall
  sudo "$fw" --setglobalstate on

}

fix_mosh_server