The most vulnerable ports for security testing

To find out to what extent a device or a network is secure, we can perform different tests. It is always important to protect the systems and thus prevent a possible intruder from exploiting a vulnerability and stealing data. In this article we are going to talk about how security tests or pentesting work and which are the most vulnerable ports and what you should take into account.

the most vulnerable ports for security testing

Most vulnerable ports for testing

A security test or pentesting aims to check if a certain computer or network is really protected. For example, if a Wi-Fi network is exploitable by an intruder or if it has good protection to prevent unwanted entries . We can do the same with ports, applications, etc.

This is very useful to enhance Internet security . In fact, many companies even hire ethical hackers to test an application or website to find vulnerabilities and fix them. Ports are used for communications between devices and it is essential to protect them. You can also test against them and there are some essential ones.

FTP ports

One of the tests you can perform is against the FTP ports, which are 20 and 21 . It is a classic protocol for transferring files. These ports allow users to use them to receive and send from a server to a computer. However, we are talking about obsolete, old ports, which today are insecure.

Therefore, they are a good option for you to carry out security tests. You can perform brute force attacks or use default credentials to access. A way to see how unprotected a server may be.


Another protocol also vulnerable is SSH. It is a TCP port that is used to guarantee remote and secure access to servers. It is also possible to brute force SSH credentials or use a private key to gain access to the system.

In this case it is port 22 . It is the one that uses this protocol by default. It is also another that has been widely used over the last decades. It has had different versions.


Following the order, port 23 is the one that belongs to Telnet. It is another old protocol, already obsolete, that can be exploited. You can use it to perform your security tests. It also allows computers to connect remotely. It predates the SSH protocol, which came about to improve security.

However, today there are still many pages that use Telnet. It is totally outdated and insecure, which is why it is the gateway for malware and attacks. It allows identity theft, stealing credentials or carrying out brute force attacks.

DNS are essential to open a web page today. They act as translators, since they are in charge of interpreting the domain names that we put in the browser and taking us to the corresponding IP address. For example, if you put this, what it actually does is translate that domain name and take you to the IP of that site, without you having to memorize it or know what it is.

An example of attacks that can be carried out against the DNS is what is known as a DDoS or Distributed Denial of Service attack. It is a way to bring down a web page and cause it to not work. It uses port 53 .


Also widely used for a long time is the SMB protocol . It is a communication protocol initially created by Microsoft and thus be able to access shared resources, such as files and printers through the network. This port has been heavily exploited in recent years. In fact, one of the most important threats such as EternalBlue took advantage of it. In this case it uses ports 137, 139 and 445 .

Therefore, if you want to petest against ports, this is one that you should put on your list. There are many exploits on the Internet to exploit this protocol.


You can also test against HTTP and HTTPS protocols. They are also very important protocols for Internet browsing. The first is not encrypted, while the second emerged as an improvement to the previous one and thus be more secure. They are widely used in the web pages you visit every day.

In this case they use ports 443, 80, 8080 and 8443 . This is where you will be able to perform pentesting and test vulnerabilities to SQL injections, for example.