Provide a small script to check whether a host is reachable via ssh, when the ssh connection is disabled/storage problems occured or whatever

gistfile1.py

import subprocess
import os

proc = subprocess.Popen(['ssh', '-v', 'user@host', 'exit'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)

for line in iter(proc.stderr.readline,''):
    if line.find("Authenticated to") is not -1:
        os.system('notify-send "Server X works again"');
        os.system('echo "Server X works again" | mail -s "Server update" yourmail@example.com')