This script uses your system's ping utility to send an ICMP ECHO_REQUEST to a list of hosts or devices. It uses a separate thread to ping each host/device. This can be useful for measuring network latency and verifying hosts are alive.

Check out more info here: http://www.goldb.org/python_pinger.html

#!/usr/bin/env python

import re
from subprocess import Popen, PIPE
from threading import Thread


class Pinger(object):
    def __init__(self, hosts):
        for host in hosts:
            pa = PingAgent(host)
            pa.start()
        
class PingAgent(Thread):
    def __init__(self, host):
        Thread.__init__(self)        
        self.host = host

    def run(self):
        p = Popen('ping -n 1 ' + self.host, stdout=PIPE)
        m = re.search('Average = (.*)ms', p.stdout.read())
        if m: print 'Round Trip Time: %s ms -' % m.group(1), self.host
        else: print 'Error: Invalid Response -', self.host
              
                             
if __name__ == '__main__':
    hosts = [
        'www.pylot.org',
        'www.goldb.org',
        'www.google.com',
        'www.this_one_wont_work.com'
       ]
    Pinger(hosts)

Output:

Round Trip Time: 14 ms - www.yahoo.com
Round Trip Time: 17 ms - www.goldb.org
Round Trip Time: 30 ms - www.google.com
Round Trip Time: 82 ms - www.pylot.org
Error: Invalid Response - www.this_one_wont_work.com

Note: I only tested this on Windows. To run on other systems, it would only require a one-line change.

I love reading old RFC's.

One of my favorites is RFC 1925 - The Twelve Networking Truths:

The Fundamental Truths

1. It Has To Work.
2. No matter how hard you push and no matter what the priority, you can't increase the speed of light.
   (corollary) No matter how hard you try, you can't make a baby in much less than 9 months. Trying to speed this up *might* make it slower, but it won't make it happen any quicker.
3. With sufficient thrust, pigs fly just fine. However, this is not necessarily a good idea. It is hard to be sure where they are going to land, and it could be dangerous sitting under them as they fly overhead.
4. Some things in life can never be fully appreciated nor understood unless experienced firsthand. Some things in networking can never be fully understood by someone who neither builds commercial networking equipment nor runs an operational network.
5. It is always possible to agglutinate multiple separate problems into a single complex interdependent solution. In most cases this is a bad idea.
6. It is easier to move a problem around (for example, by moving the problem to a different part of the overall network architecture) than it is to solve it.
   (corollary) It is always possible to add another level of indirection.
7. It is always something.
   (corollary) Good, Fast, Cheap: Pick any two (you can't have all three).
8. It is more complicated than you think.
9. For all resources, whatever it is, you need more.
   (corollary) Every networking problem always takes longer to solve than it seems like it should.
10. One size never fits all.
11. Every old idea will be proposed again with a different name and a different presentation, regardless of whether it works.
12. In protocol design, perfection has been reached not when there is nothing left to add, but when there is nothing left to take away.