How To Scan On Windows

This postal service has been reviewed and the information is still relevant every bit of June 2018.

When troubleshooting client or server side application network connectivity issues, it is frequently necessary to make up one's mind if access to a certain port that the application uses is being blocked.

In this article nosotros'll take a quick expect at how to view open ports using a number of lightweight freeware tools for Microsoft Windows. You might just be surprised at how constructive these complimentary utilities are at helping y'all to browse open ports and get to the root of the problem. Also, don't forget to check out the other 2 posts about scanning open up ports in Windows which are a continuation of this mail and use different solutions. Read Scanning Open Ports in Windows: A Quick Guide (role 2) here andScanning Open up Ports in Windows: Part 3 (NMAP) here.

NetStat.exe

The first tool of note is one many admin and support folk might have heard of; the Windows command line utility called netstat.exe. Netstat.exe, located in the Windows 'System32' folder, allows y'all to view ports that are open or in use on a particular host, but should not be confused with a network port scanner which actually probes a host for open ports.

To view which ports are listening (open) on a local host using netstat, from the command prompt type the following:

netstat –an ¦find /i "listening"

The results volition be displayed across four columns – the protocol type, local IP address and associated port number, foreign IP address, and state – as shown in the epitome below. The column of interest in this case would exist the second cavalcade.

By using the 'o' parameter as part of the netstat command, a fifth cavalcade will be displayed as part of the results. This column shows the application process ID (PID) associated with each open port. The full command would be as follows:

netstat –ano ¦detect /i "listening"

Using Task Manager to find which application is using the open port

The PID information can be used to detect which application is using the open port. For example, the image in a higher place shows PID 156 beingness associated with port 17500. By using Windows Task Manager (CTRL + SHIFT + ESC), nosotros tin can see that PID 156 belongs to the application called Dropbox.exe.

Tasklist.exe allows you to discover the application using the open port from the command prompt

The same thing can be done using tasklist.exe from the command prompt which is essentially the command line equivalent of the Windows Chore Manager that will brandish the same information. Again, the column of involvement in the results for tasklist.exe would be column ii which shows the PID for each running application. Using both versions you lot tin can display other information such as the user account that the application is running under.

For a full listing of parameters and further information, type "netstat /?" or "tasklist /?" in a command prompt.

TCPView.exe

Similar to netstat.exe is TCPView.exe which offers a more detailed representation of netstat.exe information in a graphical user interface (GUI). TCPView.exe is available for download from the Microsoft SysInternals website and runs every bit a standalone application that does non crave installation. Using TCPView, not merely can you browse open up ports but you can also view local and remote TCP connexion information such equally packets sent and received, the protocol beingness used, as well as the initiating process.

PortQry.exe

Some other really interesting tool to be aware of is PortQry.exe. PortQry.exe is bachelor for download from the Microsoft Download Heart and runs as a standalone command line application.

PortQry.exe allows you to scan open up ports on a local or remote host. Once you lot have downloaded and extracted portqry.exe to your machine, open a command prompt, and type portqry.exe followed by a given parameter from the folder that contains the executable.

For example, typing "portqry.exe –local" will show TCP/UDP port usage for the local host. The data shown when using this parameter is similar to that of netstat.exe, notwithstanding information technology also shows port statistics such as the number of port mappings and the number of ports in each land.

To view the TCP/UDP open port state of a remote host, type "portqry.exe –n [hostname/IP]" where [hostname/IP] is replaced with the hostname or IP address of the remote host. You can besides specify to scan for a particular port using the "-e [port_number]" parameter, a item range of ports using the "-r [start_range:end_range]" parameter, or a grouping of ports in a particular society using the "-o [port1, port2, port3]" parameter.

The image below shows portqry.exe existence using to scan for "listening" ports on a remote host with an IP address of 192.168.0.7 and a port range of 150-160.

For a full list of parameters and further data, blazon "portqry.exe /?".

Determination

This article has shown you how to browse open ports using a series of freeware utilities. These utilities will come up in handy every bit office of troubleshooting network connectivity issues, forming part of your network auditing toolkit or contributing towards your vulnerability checks.

The ability to scan open ports using such utilities is a corking thing to have. It can exist useful to troubleshoot network issues and is also a critical attribute of the overall network security scanning strategy.

About the Author: Andrew Tabona

Andrew has over 10 years experience in Quality Assurance, Incident Management, and Pre- and Post-Sales Technical Support roles, as well equally recent specialization in Digital Forensics and E-Discovery. He has contributed to several blogs and worked on various technical writing projects for multiple organizations, as well as existence invited to be a regular invitee lecturer and speaker at a height UK university.