The File Transfer Protocol is one of the oldest protocols on the Internet. It’s been around for longer than most other technologies still in use today and it is still the most used technology for file transfers between computers on the Internet.
Through its evolution, the technology was adapted to allow for secure transfers using TLS of SSL encryption schemes. FTP is a client-server technology. Users typically use an FTP client to transfer files to a server which, unsurprisingly, runs an FTP server software. FTP is a standard protocol so the client and servers can be from different sources and the technology will operate flawlessly. Today, we’re having a look at some of the best FTP server software.
We’ll begin with a very short explanation of FTP, what it is, how it works and where it’s coming from. Our goal is not to make you experts but to give you the necessary background to better understand our descriptions of the various tools we’ll be reviewing. That, by the way, will be our next order of business and we’ll review some of the best FTP server software we could find.
A (Quick) FTP Primer
The File Transfer Protocol was first created way back in 1971. This is almost prehistory in computer years. The protocol specification was updated with minor modifications in 1980, then in 1985. Since then, it has remained mostly unchanged. FTP is a client-server protocol where file transfers occur between an FTP server and an FTP client. Those are two very different pieces of software and, while some vendors offer both FTP client and FTP server software, no software that we know of offers both in one package.
Contrary to some other, cruder file transfer system, FTP offers a wide range of file management features in addition to simple file transfers. To the FTP client, the FTP server presents a file hierarchy which closely resembles that of a computer’s file system with folders and subfolders. In fact, an FTP server often does present part of its host computer’s file system to the client. The client is free—within its user’s file access privileges; more about this in a moment—to browse directories, list files, and sometimes perform other file management tasks.
Securing FTP transfers
Security in the FTP world is a rather complex reality. The protocol has some very basic built-in security. First and foremost, FTP uses user accounts to control access to the server. An FTP client trying to connect to an FTP server must, therefore, supply a username and password. Often, FTP servers will use the underlying operating system’s user accounts for authentication.
FTP also implements file system access control where users only have access to some files or some folders. They also could have different access rights to different files or folders. Some could be made read-only while others can be read-write. File access rights in FTP are very similar to local file system rights. In fact, most FTP servers use the underlying file system security and access privileges. There is also anonymous FTP which allows a client to connect anonymously and access a very restricted subset of the file system under the FTP server’s control.
So, while FTP provides somewhat secure access to files and folders, it has several important security flaws. For instance, the username and password are transmitted between the client and server in an unencrypted form. Anyone equipped with a packet sniffer would, therefore, be able to capture that information. That is not the only security concern with FTP, though. The biggest one is that the file transfer themselves are not secured. Each file is transferred unencrypted and could be intercepted by ill-intentioned individuals or organizations.
SFTP, or SSH File Transfer Protocol, tries to address the security issues of FTP. But contrary to what we might be led to believe, SFTP has nothing in common with FTP. SFTP is a completely different protocol which actually adds some file transfer and file management capabilities to the Secure Shell (SSH) protocol. The main advantage to SFTP as compared to FTP is that the connection and the file transfer are encrypted using the SSH protocol, shielding it from sniffing. FTP and SFTP are so different in the way they operate that many servers will do either one or the other but not both. In fact, SFTP is often a feature found in SSH servers rather than FTP servers.
SFTP and FTPS: Two Very Different Things
There is often some confusion between SFTP and FTPS. It’s understandable as they are both file transfer systems that address the security shortcoming of FTP. They way they operate is completely different, though. We’ve just seen how SFTP uses SSH to encrypt file transfers. As for FTPS, it really is an extension of the FTP protocol which uses SSL encryption instead of clear text. FTPS is to FTP as HTTPS is to HTTP.
You may be wondering which one of SFTP or FTPS to choose as they both appear to provide a secure file transfer. Nowadays, organizations tend to prefer SFTP mainly because–contrary to FTPS, which uses one TCP port for control and one for data–SFTP transmits everything on the same port, making firewall configuration a bit easier. Otherwise, both protocols provide adequate security.
The Top FTP Server Packages
We’ve searched the market looking for the best FTP server packages. We found quite a few of them and we’re happy to not only list them but also review their principal and most interesting features.
SolarWinds is a well-known name in the field of network administration. The company’s flagship product, the SolarWinds Network Performance Monitor is considered to be one of the very best network monitoring solutions. SolarWinds is also famous for its many free tools, each addressing a specific need of network administrators.
SolarWinds’ product portfolio is so vast that it seems like it has a tool for every need, including an FTP server called the Serv-U File Transfer Protocol Server. We’ll simply call it the Serv-U FTP Server. It is a simple, affordable, easy-to-use FTP server software. Its key features include file transfers using FTP and FTPS, quick and easy file transfers from the web and mobile devices, the easy transfer of multiple and large files, simple administration and management, and a secure gateway which helps avoid data at rest in DMZ networks.
- FREE TRIAL: Serv-U File Transfer Protocol Server
- Official Download Link: https://www.solarwinds.com/ftp-server-software/registration
The Serv-U FTP Server is built to support safe FTPS protocol for file transfers. You can encrypt files using SSL or TLS encryption. Transferring files using FTPS protects the data in transit and confidential information is protected from tampering, snooping, leakage or accidental exposure. With its intuitive web client and mobile device interfaces, this tools lets you easily view, upload, and download documents in very little time. And with its interactive drag-and-drop file transfer option, your users will be able to exchange files from anywhere on the fly.
For large file transfers—those in excess of 3 GB—the Serv-U FTP Server provides a free, built-in web plug-in called Web Client Pro. This plug-in also allows you to upload/download multiple files at once. Web Client Pro provides a transfer queue to pause or resume active file transfers and ask for confirmation before file overwrite.
The Serv-U FTP Server will let you perform your file transfer administration and management tasks from a single, easy-to-use management console. These tasks include real-time session monitoring and file transfer statistics, granular control over bandwidth, storage, permissions and access, access to virtual folders for local storage, remote shares, transfer ratio, and quota management for end-users, and more.
The product also lets you view and monitor FTP server logs in real-time for easier troubleshooting and error handling. The server logs will show file server startup, configuration, and shutdown information. Not only that, but it also enables you to easily add users and groups for file transfer. With the help of its wizard-driven interface, you can create new users and grant them access to the file server with nothing more than a few clicks.
Last but not least, the Serv-U FTP Server can help you easily configure file transfer settings and permissions on the file server. You can define limits for the maximum number of sessions on the server, block the IP address of a timed-out session, enable settings to require reverse DNS names, and more. The options are too numerous to mention them all.
Pricing for the Serv-U FTP Server is pretty straightforward. It is a modest $ 495 per server. Multiple servers can be used for increased capacity—each one being able to support up to 100 concurrent connections—in a load-balancing fashion or for high availability purposes. If you want to try the product before purchasing it, a free 14-day trial is available from SolarWinds.
2. FileZilla Server
The FileZilla Server is an open-source and completely free FTP server for the Windows platform. It can administer a local server as well as a remote FTP server. The product lets you choose on which ports the program will listen, how many users can be connected to the server at once, the number of CPU threads the server can utilize, and timeout settings for connections, transfers, and logins. It is very flexible and versatile.
Other interesting features of the FileZilla Server include:
- Support of passive mode FTP
- The possibility to adjust the transfer and socket buffer sizes
- The possibility of logging to a custom log file
- Bandwidth control allowing you to limit bandwidth usage
- File transfer compression with per-IP address compression exclusions
As for security, some of the product’s most interesting features include the automatic banning of an IP address after it fails to successfully login in so many attempts. There is also an option to enable FTP over TLS (FTPS) with the ability to block unencrypted FTP, and an IP filtering system so that you can block certain IP addresses or even IP address ranges from connecting to the FTP server. In case of emergency, it is super easy to take your server offline or quickly lock it down with just one click, ensuring that no new connections to your server can be made until you unlock it. Furthermore, you have full access to the creation of users and groups with the FileZilla Server. This means that you can throttle bandwidth for some users and not for others and provide select users with permissions like read/write, but other users with read-only access, for instance.
- Intuitive interface
- Perform file transfers simultaneously
- Supports secure file transfers (FTPS)
- Bookmarks for fast connections
- Can’t edit files from inside the app
- Does not refresh folder views automatically
- The 15-minute connection timeout can be a nuisance
3. Xlight FTP Server
The Xlight FTP Server is a free server that’s a lot more modern looking than FileZilla. Furthermore, it includes tons of settings that you can adjust to your liking. After creating a new virtual server, double-clicking it opens its settings. This is where you can modify the server’s port and IP address, enable security features, control bandwidth usage for the whole server, define how many users can connect to the server, and set an explicit maximum login count from the same IP address. Another interesting feature in the Xlight FTP Server is that you can set the maximum idle time for users so that they’ll get kicked out if they aren’t actually communicating with the server.
Here are some more features you might find interesting and that aren’t typically found on FTP servers:
- Server banner messages
- Email notifications
- Running a program after a user logs in
- Running a program when a file is uploaded, downloaded, or deleted
- Automatic deletion of partially uploaded files
- Upload SFV check
- Sending of deleted files to the Recycle Bin
- Access control list for directories and files
- Anti-leech protection
The Xlight FTP Server can use SSL (FTPS) and can require clients to use a certificate. It also supports ODBC, Active Directory, and LDAP authentication. The software runs on both 23- and 64-bit versions of Windows. You can download it as a portable tool that won’t require any installation or, alternatively, it can be installed as a regular Windows application.
- Supports secure file transfers
- Remote administration feature (FTPS)
- Supports multiple simultaneous connections
- Can be more difficult to use, especially for novices
- Can be complicated to configure
4. Complete FTP
Complete FTP is a free Windows FTP server that supports both FTP and FTPS. The software has a full graphical user interface and is really easy to use. The interface itself is rather plain but all the settings are hidden away in the side menu where they are easy to access. A rather unique thing about this FTP server is the presence of an “Apply Changes” button. Any change to one or more settings won’t be applied to the server until you click that button. Some will see that as a blessing, others as a curse.
Here’s a sample of what you can do with Complete FTP:
- Can allow anonymous logins
- Lets you define how many anonymous users can log in at the same time
- Show hidden files and folders
- Allow backslash separators
- Adjust timeout settings for logging in, stalled transfers, passive FTP, and idle sessions
- Define how many login attempts can be performed before a user’s access is blocked
- Lets you define a custom welcome message
You can use the Complete FTP server’s monitoring section to watch real-time logging, configure the log file, watch connections as they happen, and ban users in real-time. Step-by-step guides are built-in to the product’s installation. They let you select Step-by-step guides at the top of the program windows at any time to learn how to use the different features and options.
This software initially installs as a trial of the professional edition. The product download page provides additional instructions to learn how to activate the free edition of Complete FTP. Note that all the features mentioned above are available in the free version.
- Simple installation
- Supports encrypted file transfers (FTPS)
- Many customization options
- More features than many FTP servers
- The full menu is hidden by default
- Has occasional performance issues
- Limited features in the free version
5. Core FTP Server
The Core FTP Server is an FTP server for Windows that comes in two versions. One is a very minimal server that’s simple to understand and easy to set up in about a minute. It’s 100% portable and all you need to do is choose a username, password, port, and root path. There are also a few extra settings if you ever have a need to configure them.
The other version of Core FTP Server is the full-fledged server where you can define the domain name, have it auto-start as a service, add multiple user accounts with detailed access permissions and restrictions, designate access rules, etc.
On the product’s download page, you can pick your choice of the full program, the one with all the bells and whistles, or the portable, minimal FTP server. Also, both versions of this FTP server are available as 32- or 64-bit Windows applications
- Very quick setup
- Supports encrypted file transfers (FTPS)
- Supports Active Directory integration
- Simple management interface
- The free version only supports three domains
- There are nuisance ads for the paid version in the free one