File transfer protocol (FTP)

FTP, or File Transfer Protocol, is a standard network protocol used for the transfer of computer files between a client and server.

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FTP, or File Transfer Protocol, is a standard network protocol used for the transfer of computer files between a client and server on a computer network. It's one of the oldest protocols in use today and is a convenient way to move files around. An understanding of FTP is crucial in the realm of cybersecurity, as it can be both a tool and a vulnerability.

FTP operates on a client-server model. The client with an FTP service can make a connection to the server to send and receive files. FTP uses two separate connections between the client and the server: one for commands and the other for data. This dual connection method is known as out-of-band control.

FTP and cybersecurity

In the context of cybersecurity, FTP can be both a tool and a vulnerability. As a tool, it allows for the efficient transfer of files, including updates and patches for security software. However, as a vulnerability, unsecured FTP can be used by cybercriminals to download sensitive data, upload malware, or even launch attacks against other computers.

FTP itself does not encrypt data, which means that information transferred via FTP can be intercepted and read by anyone who can access the network. This makes FTP a common target for eavesdropping attacks, where cybercriminals intercept and read data being transferred over the network.

Securing FTP

There are several ways to secure FTP connections. One of the most common is through the use of FTPS, or FTP Secure. FTPS adds a layer of security to FTP by encrypting the data being transferred. This makes it much more difficult for anyone to intercept and read the data.

Another method of securing FTP is through the use of SFTP, or SSH File Transfer Protocol. Unlike FTPS, which adds security to FTP, SFTP is a completely different protocol that uses the Secure Shell (SSH) protocol to transfer files securely. SFTP encrypts both commands and data, preventing passwords and sensitive information from being transmitted in clear text over the network.

FTP attacks

FTP servers can be vulnerable to a number of attacks. One of the most common is the brute force attack, where an attacker attempts to gain access to an FTP server by guessing the password. This can be a lengthy process, but it can be sped up by using a dictionary of common passwords or a list of commonly used usernames and passwords.

Another common attack on FTP servers is the FTP bounce attack. In this attack, the attacker exploits the FTP protocol's ability to relay or ""bounce"" a file off of an FTP server to another server. This can be used to obscure the source of an attack, making it more difficult to trace back to the attacker.

FTP in practice

Despite its vulnerabilities, FTP is still widely used today. It's a standard part of the internet's infrastructure, and many websites and applications rely on it to function. However, because of its potential for misuse, it's important for anyone using FTP to be aware of its risks and to take steps to secure their FTP connections.

FTP is often used in corporate environments to transfer large files or to access remote servers. It's also commonly used in web development, as it allows developers to upload files to their web servers. However, because FTP does not encrypt data, it's important for these uses to be secured with FTPS or SFTP.

FTP clients

There are many FTP clients available, ranging from command-line tools to graphical interfaces. Some of the most popular FTP clients include FileZilla, WinSCP, and Cyberduck. These clients all support both FTP and SFTP, and many also support FTPS.

When choosing an FTP client, it's important to consider not only its features but also its security. A good FTP client should support secure file transfer protocols like SFTP or FTPS, and it should also have features like password encryption and the ability to clear your browsing history.

FTP servers

Just as there are many FTP clients, there are also many FTP servers. Some of the most popular include vsftpd, ProFTPD, and Pure-FTPd. These servers all support secure file transfer protocols, and they also have features like IP blocking and virtual users.

When setting up an FTP server, it's important to secure it properly. This includes using a secure file transfer protocol, blocking IP addresses known to be associated with malicious activity, and setting up a firewall to protect the server from unauthorized access.


FTP is a fundamental part of the internet's infrastructure, and understanding it is crucial for anyone involved in cybersecurity. While FTP itself is not secure, there are many ways to secure FTP connections, and it's important for anyone using FTP to be aware of these methods and to use them.

As with any technology, the key to using FTP securely is to understand its risks and to take steps to mitigate them. This includes using secure file transfer protocols, choosing secure FTP clients and servers, and being aware of the potential for FTP to be used in cyberattacks.

This post has been updated on 17-11-2023 by Sofie Meyer.

Author Sofie Meyer

About the author

Sofie Meyer is a copywriter and phishing aficionado here at Moxso. She has a master´s degree in Danish and a great interest in cybercrime, which resulted in a master thesis project on phishing.

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