Wake on lan function (working).

[lp <iv...@yahoo.com>]

Hi.

Please excuse me if this isn’t the proper place to post this, happy to
move/post it elsewhere as needed.

Recently I installed Guacamole at a site I administer and have been very
impressed with how well it works. In discussing more about the specific
operation there it seemed that a wake-on-lan facility could make a
significant difference in deployment.

Having had a look around I saw a few others had asked about this too, but
no-one has implemented such a function as yet.

Unfortunately I’m no programmer and while I recognise that either writing
something to address the API, or making an addition to the code would be the
best way to introduce it, it’s just not something I’m able to do. However I
saw that the Tomcat log file listed the unique connection number that
Guacamole uses each time a connect attempt was made to a specific machine.
From this I felt it would be possible to rough something up in Python (which
is a slow but possible process for me) that would achieve the same end.

Below is the result of this, it works seamlessly for me in my instance but
it is completely untested anywhere else so YMMV! I offer it simply in case
it helps someone else who’d like a working WOL function, if nothing else
this may give you some ideas.

For those that need to know how to make it work: you can save the script
below as a file (eg. guac_wol.py), chmod +x and run it directly
./guac_wol.py, or python guac_wol.py – note you will need to populate the
macs.list file as described below for it to work properly in your
environment.

To get the correct connection number just tail the catalina.out logfile
while you connect to a specific machine and then use that in the macs.list
file. From the half-dozen connections I’ve set in Guacamole it appears the
first one in the list is ‘2’ and they go up incrementally from there. No
doubt this is documented somewhere but I would check the logfile for sure
because this may simply be unique to my environment. BTW arp -a <ip_address>
should give you the MAC address for the machine residing at that IP address.

**guac_wol.py**

#!/usr/bin/env python2
#
# --------------------------Readme---------------------------------------
#
# Guacamole wake-on-lan (WOL) script. Luke P 26 Feb 2018
#
# This is designed to run on the Guac host machine and will send a
# 'magic-packet'wakeup call to a specified machine on the same
# network when a Guac connection attempt is made.
#
# Relies on Guac continually attempting a connect as most machines
# will not start up immediately (ie, there is no delay function from
# when the wakeup is sent to when Guac attempts a connect). Some
# machines may go through a full reconnect cycle before they fully
# wake up and a connection is established.
#
# Script reads a 'macs.list' file in the same directory as it runs from.
# File must contain only the header detail, and comma-separated fields
# of id (Guac connection number) and MAC addr. There is no error
# checking and it will likely fail if there are any other random
# characters in the file. Data from this file is compared to the
# ongoing connection data in /var/logs/tomcat7/catalina.out
# You would probably need to change this path if your system
# uses tomcat8.
#
# --- example macs.list --- #
# id,mac
# 1,11:22:33:44:55:66
# 2,22:33:44:55:66:77
# 3,33:44:55:66:77:88
# 4,44:55:66:77:88:99
# 5,55:66:77:88:99:00
# 6,66:77:88:99:00:aa
# etc,etc
# ----------------------------- #
#
# This is a rough 'n ready script and has not been tested for any length
# of time, nor on anything other than Python 2.7 in Ubuntu 16.04. It is
# offered as a concept only, if you choose to try it and it works for you
# that's great, if it doesn't, or it somehow breaks your system I'd be
# sorry but please be aware I assume no responsibility or liability!
#
# --------------------------------------------------------------------------

import subprocess, csv, sys, socket

# Define a function to send magic packet to wakeup machine.
# Takes MAC address as input & will broadcast on default NIC

def WOL(mac):
    data = ''.join(['FF' * 6, mac.replace(':', '') * 16])
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
    sock.sendto(data.decode("hex"), ("255.255.255.255",9))

# Open and tail Tomcat logfile. We can expect Guac connection
# data to be logged here. This includes the Guac username that connects
# out to another machine on the network, and the connection number from
# the connection list in Guac. This list appears to be numbered as the
# first being #2 (assume #1 is the logged in user that created the
connection?).

logfile =
subprocess.Popen(['tail','-F','/var/log/tomcat7/catalina.out'],stdout=subprocess.PIPE,stderr=subprocess.PIPE)

# Start reading the logile data line by line as it arrives.
# Open the macs.list file to get machine connection numbers and associated
# MAC addresses. Then continue to read logfile for Guac username and
connection
# number. If a match is found between the logged connection number & id
number
# from list file, call the WOL function to wakeup the machine via the
associated
# MAC address (ad infinitum).
#
#
# Could also use the username instead of id number but some users may have
multiple
# connections....

while True:
    line = logfile.stdout.readline()
    with open('macs.list') as inifile:
        reader = csv.DictReader(inifile)
        if 'connected to connection' in line:
            q1 = line.find("\"")
            q2 = line.find("\"",q1+1)
            q3 = line.find("\"",q2+1)
            q4 = line.find("\"",q3+1)
            user = line[q1+1:q2]
            conn_num = line[q3+1:q4]
            for row in reader:
                if(row['id']) == conn_num:
                    WOL(row['mac']) 



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