Monday, March 24, 2008

Testing Network Ports from Windows

This article provides information on how to effectively test network connectivity between a local and remote endpoint on specific network ports and protocols.

Several methods are described, including portqry, port reporter and telnet.

Using PortQry.exe 2.0

The PortQry utility provides the flexibility to test any port number or range over TCP and UDP, as well as forcing a local source port and the destination. From a command prompt, run:

  1. portqry -n %server% -e %endpoint% -v

For example:
Portqry -n server1 -e 135 -v
Portqry -n server2 -e 53 -v -p BOTH
Portqry -n server3 -e 80 -v

Note that in the first example above, if RPC to server1 was not permitted, the result would be 'TCP port 135 (epmap service): FILTERED', whereas if it were allowed, a list of UUID's currently recorded by the endpoint mapper would be returned (also useful information in some cases).

Using telnet.exe

Remote endpoints on a particular TCP port that return a response (such as HTTP, FTP, SMTP etc) can be easily tested with telnet, from a command prompt run:

  1. Telnet %remoteServer% %Port%
  2. If the connection is established you may need to press enter or escape to receive a further response.

For example:
Telnet server3 80

Using Port Reporter

Locally on the machine:

  1. Obtain the port reporter tool from
  2. Install PortReporter by running: pr-setup -d '%systemroot%\temp'
  3. Start the PortReporter service: net start portreporter
  4. Perform the actions you want to log, log files are stored in %systemroot%\System32\LogFiles\PortReporter, PR-PORTS* contains the recorded port activity
  5. Stop the PortReporter service: net stop portreporter
  6. Uninstall PortReporter by running : pr-setup.exe -u


  1. See the reference to article 837243 for more information on how to interpret the log files
  2. The PR-PORTS* log file is formatted by: date,time,protocol,local port,local IP address,remote port,remote IP address,PID,module,user context


New features and functionality in PortQry version 2.0

How to Make Portqry.exe Only Report Listening Ports

How to Use Portqry.exe to Troubleshoot Microsoft Exchange Server Connectivity Issues

How to Use Portqry to Troubleshoot Active Directory Connectivity Issues

Availability and description of the Port Reporter tool

Wayne's World of IT (WWoIT), Copyright 2008 Wayne Martin.

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About Me

I’ve worked in IT for over 20 years, and I know just about enough to realise that I don’t know very much.