How to Find Open and Blocked TCP/UDP Ports

There is a possibility that the current app that you are using might be complaining due to the blocked ports or a few ports that are left open which can cause security problems.

TCP is connection-oriented which means that in this type of connection, there is an existence of negotiation that takes place between two devices and it is well maintained till one of the sides terminates it. The session can be monitored, and the dropped package or errors can be detected. The size of the packets exchanged may vary depending on the data rate and line quality.

UDP is not connection-oriented. There is no existence of sessions or negotiations. Packets are transferred from one device to another without any prior announcement t o process. There will be no feedback that can detect whether the packets are transferred successfully or not.

How to find open and blocked TCP/UDP ports?

There are several ports. A port number can be anything from 0 to 65535. The port numbers ranging from 0 to 1023 are the most important ones. They have basic network services. Port numbers ranging from 1024 to 49151 are some of the registered ports. They are assigned with common services like open VPN. Most of the other port numbers are dynamic and private.

Here is how you can find the open and blocked TCP/UDP ports -

• First, you have to find out which ports are open and can be used on your computer.
• Go to the start menu and search for CMD.
• After searching for CMD right right-click on it. Further, select the "run as administrator" option.
• In your command prompt search for Netstat -ab.
• A long list will be displayed in front of your screen you have to copy and paste this into the next editor.
• All the details in the brackets are the enamesnamese of the programs that are using the port.
• The number will have an IP address and port number after a colon.
• Now you will have to look for the ports that are being used by the apps. For this- 
• You have to first go to the "start menu" and search for CMD.
• After searching for CMD right-click on it.
• Now you have to enter " netsh firewall show state" on the command prompt.

This is how you can find the open and blocked ports based on your Windows firewall configuration.