WOL from outside WAN

Question

A while ago, I wrote [with some help from Google] a small WOL script to switch on the computers in my network. Here is the script:

exec /usr/bin/python -x "$0" "$@"
#
node_lst = [
        'srv1 0a:1b:8c:0d:2e:7f',
        'srv2 0A-0B-4C-8D-CE:3F',
]
#
import os,sys,string,commands
import struct, socket
import re,random

retval = 0

mac_addr = "mac_addr.txt"
X = '([a-zA-Z0-9]{2}[:|\-|.]?){5}[a-zA-Z0-9]{2}'
S = re.compile(r'\s+')

mmap = {}

## First argument 'None' in str.translate is new in 2.6. 
## Previously, it was a string of 256 characters 
if sys.version_info < (2, 6):
    f1_arg = ''.join(chr(i) for i in xrange(256))
else:
    f1_arg = None

## broadcast address
sysOS = "uname -s"
BSD = "ifconfig | grep -w broadcast | cut -d\  -f 6"
LNX = "ip -o addr show | grep -w inet | grep -e eth | cut -d\  -f 9"
#
if commands.getoutput(sysOS) == "Linux":
    bCast = commands.getoutput(LNX)
elif commands.getoutput(sysOS) == "Darwin":
    bCast = commands.getoutput(BSD)
else:
    print "System not supported!!"
    sys_exit()

def WakeOnLan(mac_address):

    ## Building the Wake-On-LAN "Magic Packet"...
    ## Pad the synchronization stream.
    data = ''.join(['FFFFFFFFFFFF', mac_address * 20])
    msg = ''

    ## Split up the hex values and pack.
    for i in range(0, len(data), 2):
        msg = ''.join([msg, struct.pack('B', int(data[i: i + 2], 16))])

    ## ...and send it to the broadcast address using UDP
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
    s.sendto(msg, (bCast, 9))
    s.close()

def sys_exit():
    sys.stdout.flush()
    sys.exit(1)

## check if hostname is provided
if len(sys.argv) != 2:
    print "Usage: %s <hostname>" % sys.argv[0]
    sys_exit()

for i in node_lst:
    # strip off everything from first "#" [if] found
    i = i.split('#',1)[0]
    if not re.search(X, i):
        continue

    h = S.split(i,1)[0]                 ## host name
    m = S.split(i,1)[-1]                ## MAC address
    mmap[h] = m.strip('\t|" "')

for j, k in mmap.iteritems():
    if sys.argv[1] == j:
        if not re.search(X.replace('zA-Z','fA-F'), k):
            print "Invalid MAC address [",k,"]; nothing to do!!"
            sys_exit()
        else:
            WakeOnLan(k.translate(f1_arg,':.-'))
            print "WOL request has been sent to %s [%s]" % (j,k)
            break
else:
    print "Host [%s] doesn't exist!!" % sys.argv[1]
    sys_exit()

Which works just fine from inside my home network (or LAN). How can I change the script to make it work for outside of my LAN? Any idea or suggestions? Cheers!!

Answer 1

This is not possible because WOL packets are broadcast packets (since you can't know who to send it too). Home routers and especially ISP/Network routers discard all broadcast packets because else everytime you run this one script all the computers on the entire internet would receive your package, which would cause quite some clutter.

What you of course can do is write a small application that is on a computer that is running inside the WAN in which you wish to turn on all computers, and then have that application send a WOL packet. However this would require a computer with internet access to be turned on at all times.