What is FTP Server?

Introduction

FTP stands for File Transfer Protocol, which is a basic and old network technology. It has been used for many decades to transfer files over the internet. Basically, it is a protocol that is used to transfer files from a computer (client) to a server with the help of a network.

Even though, in modern times, many new and advanced file-sharing methods exist, FTP is still widely used as it is simple and works efficiently. This write-up takes a detailed journey into the domain of FTP servers.

What is an FTP Server?

FTP Server is a computer (or software), which stores files and allows users to upload, download, and manage files by using the FTP protocol. It works by using a rule set called the FTP, which tells computers how to send and receive files.

The setup's simple: the server holds the files, and people (the clients) log in to grab or send stuff. You need the right permissions to get in, which keeps things organized and secure, especially for teams that need to manage shared files.

Mostly, FTP servers exist to make moving files around easy and reliable. They run on TCP/IP networks and focus on two main jobs: letting you upload files from your computer to the server ("put") and letting you download files from the server to your machine ("get").

Why Is an FTP Server Used?

Well, they are perfect for sending big files that email just can't handle. They also support secure transfers, such as FTPS or SFTP, so your data stays safe. Plus, they make life easier with features like bulk uploads, scheduled transfers, and a single spot to store everything.

You can set up user roles and permissions for better control, and many companies lean on FTP servers for automatic, ongoing backups, so if something goes wrong, you're covered.

Features of FTP Servers

FTP servers come with a bunch of handy features. They use a client-server model: you send a request, the server handles your files and folders. Usually, you'll need to log in, and admins can set different permissions depending on what you're allowed to do. Security matters, so lots of servers offer encrypted options like FTPS or SFTP.

They support both text files (ASCII mode) and everything else, like pictures or videos (binary mode), so your files transfer without a hitch. Users can do more than just upload and download. You can browse folders, create or delete directories, rename files, and tweak permissions from wherever you are.

Modern FTP servers let you connect through FTP apps, web browsers, or even secure links, so you've got options. They can handle both active and passive modes, which just means they work well with all kinds of network setups, even tricky firewalls.

When people talk about FTP access, they mean the ability to log into one of these servers and manage files. Usually, you'll need a username and password, but sometimes servers let folks in as "anonymous" users, though you'll only see a limited set of files that way. You connect using FTP client software or a web browser that's set up for it. Security protocols and access controls keep your remote file work safe and smooth.

How does FTP work?

FTP is based on a client-server architecture. The client initiates connections to the FTP server, and the latter generally listens at port 21 for incoming requests. It supports two channels of connection.

1. Control Channel: It sends commands such as login, change directory, list files across to the server, and receives responses. It will remain open throughout the duration of the session.
2. Data Channel: It is used for transferring only file contents or directory listings. This channel opens when needed and then again closes after the transfer activity.

The flow of the FTP session is as follows:

• Client initiates a control connection to the server.
• Authentication is the process that occurs.
• Client dictating, server acting.
• This is a data connection opened when a file transfer or directory listing is requested.
• The connection for data is closed right after the transfer.
• The control channel remains open, perhaps for upcoming commands.

FTP is one of the primary protocols for file transfer, but the choice of authentication method and mode of transfer has a great impact on its security. In a restricted environment, it is advisable to favor encrypted authentication and passive mode when firewalls are around.

What are the types of FTP server authentications?

FTP provides authentication mechanisms based on different levels of security. The list of FTP authentication mechanisms includes:

Anonymous Authentication

Users can log in with any generic name as the username and the email address as the password. The generic name is always 'anonymous'. It is largely used for publicly accessible file repositories, but now it carries certain security threats if it is not limited.

Basic Authentication

It requires a unique username and password. The password is transmitted as plain text. It is not advised to use confidential data. It faces a potential risk of being intercepted.

Digest Authentication

A hashing algorithm is used for authentication if there is a chance of interception. This method is more secure than basic authentication.

"SSL/TLS (Secure FTP or FTPS). In SSL/TLS, encryption is used for all data, including usernames and passwords. Thus, it is highly suggested for transferring confidential data securely."

Key-Based Authentication

Use of public/private keys for authentication rather than passwords. Only those people possessing the correct private key can access the server.

Is FTP Server a File Server?

Yes, an FTP server can also act as a file server. The main function is to enable clients to upload, download, delete, rename, and move files on the FTP server.

Here is how an FTP server works as a file server.

File Storage: The use of the FTP server enables users to upload files for storage. The files may be stored within created directories, which can only be accessed by users with appropriate rights.

File Sharing: Users can download, upload, and share files. This feature has remained a core objective of file servers.

Access Control: Authentication and authorization facilities are available at ftp servers.

Network Accessibility: Different operating systems can access an FTP server. There is local and remote management of the files of the operating system. Although FTP servers are file servers, not all file servers are FTP servers.

Others may include SMB/Windows, CIFS, NFS/Unix/Linux, or SFTP protocols. FTP is one of the oldest protocols available for file sharing over a computer network. Because FTP does not offer any encryption, this can be a danger when using this protocol in the sharing of sensitive information.

Examples of FTP server

FTP servers are basically programs that let people transfer files over networks, right? They handle stuff like uploading website files or sharing documents securely.

1) FileZilla Server

One example is FileZilla Server, which runs on Windows. It is open source and pretty straightforward to set up, especially with that graphical interface. Beginners like it because it does not take long to get going. Web developers use it to send HTML, CSS, and images to hosting servers.

Small teams might use it for internal sharing too, if they set up firewalls correctly. It can even help with backups using some scripts for automation. I think it is written in C++ and just uses regular Windows stuff, no big web frameworks needed.

2) Very Secure FTP Daemon (Vsftpd)

 Vsftpd, which stands for Very Secure FTP Daemon. It works on Linux and Unix systems mostly. Security is a big deal here, along with speed and not crashing. A lot of Linux distros like Ubuntu or Red Hat come with it built in. People use it for managing website files on servers or just general admin tasks.

It supports FTPS for encryption, and you can set it up for anonymous access if you want public downloads, though that is not as popular now. Virtual users are a cool feature; they keep things safer without messing with real accounts. It is in C and runs light as a daemon, config in files like vsftpd.conf.

3) Pure-FTPd

Pure-FTPd is similar, another open source one for Unix-like systems. It focuses on security, too, and simplicity. Web hosts like it because of chroot, which locks users into their folders. Supports FTPS and virtual users, plus ties into MySQL or LDAP for auth in bigger setups.

It is efficient and works on Linux, macOS, BSD, and even Solaris. Written in C, configured via command line or scripts that read files. Seems like it is good for places with lots of users, like ISPs.

4) Microsoft IIS FTP Server

For Windows, Microsoft has the IIS FTP server built into Internet Information Services. It lets you run web stuff and FTP on the same machine. Organizations use it to manage site content and integrate with Active Directory for security.

Developers test apps locally with it sometimes. Runs on server versions like 2016 up to 2022, or even Windows 10 Pro. You configure through the IIS Manager, which is graphical, like FileZilla.

All these examples show how FTP servers fit different setups, from simple Windows ones to secure Linux options. FileZilla and IIS for Windows crowd, vsftpd and Pure-FTPd for Unix. Security keeps coming up, especially with FTPS. It helps to choosing depends on your OS and needs.

Advantages of FTP Servers

FTP Servers are used to store and transfer files over a network or the internet. Below are the main advantages of FTP Servers explained in easy language:

• One big plus is how it handles large files efficiently. You can transfer them quickly over the internet or just on a local setup. And it supports multiple directories too.
• Also, the resume feature in many clients is handy. If something interrupts the transfer, you don't have to start over from scratch. Especially for huge uploads or downloads, which saves bandwidth and frustration.
• FTP lets you do batch processing, meaning you can send multiple files or whole folders at once. That's useful for automation, like scripting backups or syncing files on a schedule. It works across different operating systems, so it's platform independent, which makes it a universal kind of tool for sharing.
• Admins get control over access, setting permissions so users only see certain files or folders. You can pause transfers, manage queues, all that. And it's widely supported, with tons of clients out there. Web developers use it to upload site files directly to hosting servers, which seems straightforward.

Disadvantages of FTP Servers

The main one is security, since traditional FTP sends everything in plain text. User names and passwords go out unencrypted, so anyone snooping with a packet sniffer can grab them easily. Files too, like personal documents or financial stuff, no protection.

• That leads to risks like interception or even modification during transfer, and the client or server might not even know. Brute force attacks are another problem, where someone just keeps guessing logins without any built-in limits, unless you configure it manually.
• No integrity checking either, so you can't tell if a file got corrupted or tampered with on the way. And for sensitive data, it's obsolete, better to use FTPS or SFTP instead.
• Setting it up securely is complex, especially with firewalls and NAT. In active mode, the server tries to connect back to the client, which firewalls block a lot. Passive mode helps sometimes, but there are still challenges, and it might open holes if you're not careful.
• Logging and error handling are limited compared to newer tools. You might not get details on why a transfer failed, making troubleshooting harder. Basic FTP doesn't do compression or automatic sync, so for those, you need something more advanced.
• For beginners, the basics are okay, but securing them with modes and firewalls gets challenging. Anonymous access can be risky if not locked down to read only in a safe directory; malicious files could slip in.

Overall, FTP servers are fine for basic non-sensitive transfers, but the lack of encryption from the start makes them vulnerable. It feels like it's more of a legacy thing now, with workarounds for security that complicate everything.

Alternatives to FTP Servers

Traditional FTP servers were never designed with security in mind. Exposed to credential interceptions and brute-force attacks with no inherent encryption, a more secure method of file transfer soon emerged.

If security, reliability, and compliance are paramount in your organization, applying an encrypted alternative to FTP is highly recommended. Some of the most used and trusted alternatives include:

SSH File Transfer Protocol (SFTP)

SFTP operates over the Secure Shell (SSH) protocol, providing end-to-end encryption for both authentication and file transfers. The communication is done via a single secure channel, usually over port 22. It supports strong authentication methodologies like passwords and public-key authentication. Because it is so simple and secure, and friendly to firewalls, SFTP is widely regarded as the default standard for secure file transfers.

FTP Secure (FTPS) / FTP over SSL/TLS

SSL/TLS encryption in FTPS increases the security level compared to traditional unencrypted FTP. FTPS can protect both the command channel and the data channel in such a way that any credentials and file contents are sent completely encrypted during the transfer. FTPS can work in two modes:

• Implicit FTPS, where encryption is enabled from the start, usually on port 990
• Explicit FTPS, where encryption is requested after connecting over the standard FTP port 21

While FTPS improves security, it can be more complex to configure than SFTP due to its dual-channel communication model.

Secure Copy Protocol (SCP)

SCP is another tool that uses SSH as a mechanism to securely copy files. While SCP is able to offer encryption and authentication, this tool is especially designed for a mere copy function. Compared to SFTP, SCP is less feature-rich. For example, SCP does not offer browsing or resume capability.

HTTPS for File Transfers

The use of HTTPS involves the use of SSL/TLS to provide the necessary encryption for the processes involved in the transfer of data on the web. This security feature makes it very easy to use, and it has been employed for use in applications of file transfer through the use of browsers. However, it might prove to be less flexible compared to the other processes.

Managed File Transfer (MFT) Solutions

Managed File Transfer software is designed for complex and high-volume file transfers. These tools can handle multiple secure protocols like SFTP, FTPS, and several other protocols.

They include other functionalities like automation of workflows, guaranteed delivery, auditing, and more. Because of the advanced encryption and authentication mechanisms, Managed File Transfer software is most suited for businesses that have strict policies for security, governance, and regulatory compliance.

A brief about how to set up an FTP Server?

Installing an FTP server consists of choosing software, defining user accounts and access, and allowing network access, depending on the operating system being used. For instance, to install on Windows, you would use FileZilla Server, which has easy installation requirements and setup.

First, you need to have a machine you manage as an administrator, an accessible IP or dynamic DNS in case you have a changing IP address, and firewall rules permitting FTP traffic access.

Finally, after installing FTP server software on your computer, you set up administration options, establish user accounts and groups, and set read and write access to specific folders in those groups.

The shared folders must have correct access rights, and it's recommended to allow user access only to personal home folders for security reasons.

Then, you have to allow FTP traffic through your local firewall to enable access to it from the internet if it's directly accessible to everyone through your router. Finally, to check if it works properly, you have to use a client to check if it's connected and accessible, and if you have access to its files.

Summary

FTP is quite efficient and reliable for file transfers, but not for applications involving highly sensitive content. It is not an encrypted protocol, but it is still in use for tasks such as software distribution.

But where high-level security is a requirement, SFTP would be a good alternative. The speed advantage of FTP makes it more preferable than the new generation of competitors. Indeed, the classic networking standard will continue to be used for many years to support the existing infrastructure.