Testing TCP Network Firewall Ports from ESXi

As we all transition to ESXi there are certain activities that we need to figure out a new way of doing. One item that comes up in new deployments is making sure that all of the ESXi –> firewall rules are defined correctly.

I do not believe that there is a way to do this from the SDK so its off to Tech Support Mode. Unfortunately there is no telnet, netcat, or other network tool that I typically use.

Python to the rescue:

#!/bin/env python
import sys
import os
from socket import *
def usage():
    print "USAGE: %s <host> <port>" % (sys.argv[0],)
# Check the # of parameters
if not len(sys.argv) == 3:
# Check that the host and the port are appropriate.
    host = sys.argv[1]
    port = int(sys.argv[2])
print "Attempting a TCP connection to host '%s' on port '%s'.\n" % (host, port)
    s = socket(AF_INET, SOCK_STREAM)
    s.connect((host, port))
except Exception, e:
    print "Connection Failed: %s." % (e,)
    print "Connection successful."

Python can also send UDP packets fairly easily, but since there is no connection the only way to tell if the traffic worked is to monitor it on in the network or on the destination side. As a result it is just as easy to do the operation that requires the port and if it fails, set up the traffic monitor.

Comments (2)

  1. E. Jacob Hayes

    I have a custom PowerCLI based Startup & Shutdown script that does dependency checking. The script incorporates checks to ensure our oracle database server processes and tnslistener ports are up and running. I had used new-object net.sockets.tcpclient to define a data type that I could use to check the oracle ports with.

    This guy is doing a similar thing with his Powershell script: http://halr9000.com/article/418

    So far I’ve written a ton of scripts in Powershell/PowerCLI for our vSphere environment and have not run into a roadblock yet as far as functionality using .net extensions. Am now looking to delve into WMI calls as well to extend our current script repository even further.


  2. Eric (Post author)

    Good pointers for testing if TCP ports are open from a Windows box.

    Do you have a development background? If not, how did you begin to use .Net in PowerShell?

    I have seen non dev oriented admins have problems using .Net directly and was thinking of doing some posts to help people head down that road.

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