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What is a Port Scanner?

Protecting your network from external intrusions is of vital importance.

It is very important for companies and officials to make sure that they employ the most thorough techniques and technological advancements that are available in order to ensure that a proper system can be created.

Using a port scanner is of vital importance for any networking company.

Basically, a port scanner is a computer software program that is designed to test a server or any host and find if there are any open ports.

If there are, it means that the server is facing an external threat, and can be accessed externally.

As a result, it is important to make sure that the external ports are closed.

Using a port scanner is crucial because it helps the company figure out if there are any sort of security threats that the company faces.

What does a port scanner do?

Usually, port scanners are used by administrators in order to verify different security policies of their networks, while attackers and hackers also make use of these port scanners in order to identify the number of different running services that are active on a host, with a view to compromising the system.

The attack is commonly known as a 'port scan'.

Basically, a port scan sends a number of client requests to a vast amount of server port addresses on a host, primarily to find an active port and exploit any sort of vulnerability that might exist within that service.

However, the vast majority of the uses of a port scan aren't really of such an offensive nature.

Instead, these are simple probes that are usually made by company administrators in order to figure out whether the services are available on a remote machine or not.

Types of port scanners

There are a number of different kinds of port scanners that are used.

First of all, the common kind of port scanner is one that makes use of the networking functions of the operating system and is primarily the next possible option that is chosen by people whenever the SYN is not considered to be a feasible option.

Another very common form of port scanning is the SYN scanning.

The SYN scanning does not make use of the network functions of the operating system however, but instead it creates raw packets of IP on its own, and then monitors these packets for any sort of response that might be received.

Such a scan is commonly referred to as a 'half open scan'.

The reason why they call it a 'half open scan' is basically because it never opens up a full TCP connection, but instead makes use of a SYN packet to monitor the response.

Other common types of scans include the UDP scanning, but this one comes with a number of technical challenges that must be brought in to question.

Primarily because the UDP is a connection less protocol and as a result, there's no TCP SYN packet to be used.

Other common options include the ACK scans, the FIN scanning, the proxy scan, the window scanning, etc. 

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Port Scanner