Catch exceptions about andreth HOT 3 CLOSED

# python andreth.py
enabling IPv4 forwarding
configuring firewall
setting up PPP tunnel
Traceback (most recent call last):
  File "andreth.py", line 223, in <module>
    main(args)
  File "andreth.py", line 181, in main
    establish_tunnel(args.local_ip, args.remote_ip)
  File "andreth.py", line 106, in establish_tunnel
    subprocess.check_call(tunnel_cmd)
  File "/usr/lib/python2.7/subprocess.py", line 499, in check_call
    retcode = call(*popenargs, **kwargs)
  File "/usr/lib/python2.7/subprocess.py", line 486, in call
    return Popen(*popenargs, **kwargs).wait()
  File "/usr/lib/python2.7/subprocess.py", line 672, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1213, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory


closing tunnel
ERROR: Could not destroy tunnel device
disabling IPv4 forwarding
reverting firewall rules

# Permission to use, copy, modify, and distribute this software