What is FTP Connection?

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By Vijay Singh Khatri

FTP is the abbreviated form of File Transfer Protocol. FTP is used to send the data from one computer to the other using the network. There are many places where FTP is used, and each one has its own way of sending the files. Most companies across the globe use FTP to transfer the files between the computers and the server. On the other hand, websites use FTP to download their content from the server on which they are hosted in the first place.

In this article, we are going to show you how FTP is being used in your network. Besides, we will also show the working of FTP, its advantages, and the different types of FTP that networks are using to transfer the files from one place to the other. So let’s begin!

History of FTP

The very first specification of FTP was published in the year 1971 under the name RFC 114. The man who created the FTP was Abhay Bhushan, a student from MIT. The main goal for the FTP during that time was to develop a protocol that enables the transfer of the files over ARPANET, which used to work like the Internet in those years.

When the modern Internet started taking shape, the FTP went on to have several changes. Each reversion in the FTP protocol was done to make it align with the networking standards of that time. That also includes TCP/IP. Then in the year 1980, a new form of FTP was developed by Jon Postel when working with RFC 765. Then five years later, FTP was again defined with RFC 959, which resulted in the introduction of new management capabilities for the FTP protocol.

This gives FTP the ability to create and remove a file directory. Before this, most of the FTP iterations were only able to transfer files from the existing directories present. With the new update defined in RFC 2228, the FTP now has security capabilities. The final update that we see now happened two years later, in 1999, with RFC 2428, which resulted in FTP starting to support the IPv6 protocol as well.

How Does FTP Work?

The connection is known as FTP forms between two systems. So the two systems can communicate with one another over the network. As a result, if you want to make the connection, you first need to get permission from the sender by providing your credentials to the FTP server, or you can even use anonymous FTP.

When the connection between the two systems is established via FTP, the connection forms two different types of communication channels — command channels and data channels. The primary usage of the command channel is to send the commands and their response from the client to server and server to client. If we look at it, FTP uses the same form of communication as done by TELNET or SMTP. That is used to communicate across the control connection. On the other hand, FTP uses the NVT ASCII character, which is set up for the communication for port number 21.

The data channel in FTP is used for transferring the data to and fro from the client-server connection. The data channel uses port number 20. When the system works as the client uses the FTP, it gives the FTP command along with the FTP server address. When the server and the client get connected with one another, the user can make the log in via ID and password. In addition to this, even if the user is not registered with the server, he can access the files present on it using the anonymous login where the password is the client’s email address.

Once this is done, the server will check the credentials and allow the client to access the files. The client will transfer the desired file and then exit the connection.

FTP Modes of Data Transfer

There are three different modes of FTP file transfer, and your system can choose any of them based on the requirement of the application that is asking for the files.

  • Stream Mode – This one is set by default, and here the data bits are transferred from FTP to TCP in the form of stream bytes. Here TCP is the one that needs to do the following role of cutting down the data into small segments. The data transfer will automatically close when the data stream stops. Otherwise, the sender will close out the connection manually.
  • Block Mode – When your network is using block mode, the data is transferred from FTP to TCP, but here it is sent in the form of blocks. Besides, each block of data has a 3-byte header attached to it. The first byte holds the information, such as the description of the block. The other two are used for describing the size of the block.
  • Compressed Mode – This one is used for transferring large numbers of files from one system to the other. We know due to the size limit, we cannot share big file sizes over the Internet. As a result, a compressed mode is used to decrease the file size and then send it across the Internet.

What Do You Mean by Anonymous FTP?

Anonymous FTP is used when the sites have files that are available for the public to access with no validation of the ID in the first place. As a result, if you want to access these types of files, you don’t need to put in any username and password. What it means is the username is set to anonymous, and the password is set as the guest or the email of the website. Keep in mind that the access of the user in an anonymous FTP connection is pretty limited. For example, a user can copy the files, but he doesn’t have enough freedom to navigate through the directories.

What Do You Mean by FTP Clients?

FTP clients are the ones that are used for downloading, uploading, and managing files that are present on the server. There are several FTP clients for you to choose from; in the end, it should be your decision based on the requirements and your users as well.

  • FileZilla – This one is a free FTP client developed to work with both Windows and macOS. You can use it with Linux-based servers as well. The FileZilla supports both the FTP and FTPS file transfer protocols.
  • Transmit – This FTP client is explicitly developed for macOS, which comes with the support of FTP and SSH.
  • WinSCP – Windows FTP client that comes with the support of FTP, SSH, and SFTP.
  • WS_FTP – Windows FTP client, which has the support for SSH.

Use of FTP

There are many places where FTP is being used in our daily lives, and we don’t even know about it. The operations of FTP span from business-to-business and peer-to-peer data transfer. Given below are some of the most common use cases of FTP that everyone should familiarize themselves with.

  • First, organizations use the FTP, which makes it possible for the employees of the company to share their files across the different branches that are spread around the globe. Companies like Google, Facebook, Accenture, and more use FTP to send their confidential data over to their other offices using the FTP protocol.
  • Employees of a company or a business also use the FTP protocol when it comes to sending files to external business partners or customers in a safe way.
  • The IT team can use FTP to transfer back the data to disaster recovery (DR) sites.
  • On the other hand, website development teams can take advantage of FTP to send the content of their website and web application to the server in the most secure way possible.

Benefits of FTP

There is more than one option to send files across the Internet. But still, most of the networks are using FTP, so what does that mean? Well, given below are the five benefits that companies can get when they are using FTP protocol for file transferring in comparison to other protocols.


One of the first things that come to the mind of a user who is sending the data over the Internet is how secure the communication is going to be? Both FTPS and SFTP come with encryption in their file transfer protocols. These two protocols add up another layer of security to the traditional FTP file transfer protocol. Right now, most FTP servers can work with both FTPS and SFTP to protect the shared data. As a result, you have the assurance that your files are not going to fall into wrong hands when they are being transferred. This could be vital when you are sending sensitive data and have a concern that other parties might not intercept that transfer.

The thing is when the data is being sent over the Internet, the person who has a little bit of knowledge and has the right tools can intercept the file transfer. On the other hand, you might fear that your files may be subject to a virus attack during transfer. But with the use of an FTP server, these issues are drawn to the expert who is handling the server. Thus, it’s their responsibility to eradicate any issue present in the file transfer and make it secure for you.


With FTP, you are getting better control over how your data is being sent. The best FTP servers that are leading the industry offer granular access controls to the users. This gives server administrators the ability to choose which user can upload, download, edit and share the files. Besides, the administrator can give special permission to users for the specific folders.

The thing is, not everyone in your organization needs to have the right to access the files that are specified to be viewed and edited by the CFO of the company. These files are too sensitive and can provide a significant threat if any lower-level employee compromises them. With the ability to control the file and solution access for the individual user account, the FTP protocol gives the users a ton of control options.

Large File Size

Suppose you have sent a file to someone using the email. You know you are not allowed to send files bigger than 25MB. You get the message that the file is too large to be sent via email. So, if you are dealing with a massive amount of data and you don’t want the file transfer to be interrupted in any way, you should use an FTP server that makes it possible for you to send gigabits of data all at once without any hassle.

Improved Workflow

When you have not established a proper uniform process of file sharing in your organization, you have to face the slowdown of the workflow. This could hugely impact the business productivity of your company. Instead of sharing a single file at a time, you can send multiple files across the network with ease using the FTP protocol. You can even schedule when to send the files to a specific server. It could be done on weekends, nights, and also at the time specified by the user. In that way, your workflow will not be interrupted.

On the other hand, when you have an FTP server, all the files are located in a single location. This reduces the time your team spends hunting down the exact location for the specific piece of data. Likewise, it also eliminates the chances of losing your files on multiple servers.

Disaster Recovery

You never know when you have to deal with the loss of data or the data getting compromised. That’s why when you are choosing the FTP provider, the vendor you choose will make sure that your files are never lost. It doesn’t matter if it’s your everyday data or the most sensitive confidential files. The vendor will keep all of the security on the FTP server using the redundancy techniques.

On the other hand, when a disaster happens, such as the interruption of the Internet or a power outage due to a natural calamity, you don’t want to lose the work you have been doing. FTP servers are designed in such a way that they regularly backup the files to another location, if in case you have found some data to be lost, you can contact the FTP vendor and ask them to give you the links to the misplaced or lost files from the backup.

Types of FTP Connection

There are two types of FTP connection, each one of them is defined below.

Active FTP Connection

When the system is using an active FTP connection, that means the client is responsible for the establishment of the command channel. On the other side, the server is the one that does the work for the data channel and establishes it in the network. When the client is requesting the server to send over the data using the network. The server takes the request and then initiates the transfer of the data to the client. This is not an ideal connection between the user and the server. That is because it could run into a ton of problems when there is a firewall in between the client and the server to keep the attackers from entering the network.

Passive FTP Connection

Here the client is responsible for establishing both the data channel and the command channel. When the client is asking for the data from the server, the server sends a random port number to the client. When a client receives the information for the port number, it establishes a data channel to the server using the port number. This is a more common way of sending and receiving files using an FTP connection. This is because even if the firewall protects the client, the server is still able to send the file to the client with ease and total secrecy.

Restricting the FTP

You can control the FTP connection that your system is using both on the user level and the listener level as well.

Restricting the FTP at the User Level

For the user, they restrict the working of FTP with the help of Require Secure Control and Require Secure Data constraints. These two will make sure that the connection is encrypted using either the FTPS or FTPES. In case the user is trying to get access to files without upgrading the connection to the encryption first then the user will be denied login from FTP over Port 21. On the other hand, when the connection is upgraded to the encryption i.e. FTPES then the user is allowed to log in using the credentials. The network does require an FTP listener, so it can be used to give access to FTP or FTPES connections based on the requirements.

With the user or a group allowing the constraints such as FTP or FTPS means that it gives instructions to what protocol can be used for logging in to the system. If you select Allow FTP, that means both the FTP and FTPES connections will be allowed for the login attempts via FTP listener. You can further restrict it to FTPES connections only with the use of Require Secure Control and Require Secure Data constraints from the user end.

Restricting the FTP at Listener Level

With the fine-graining of the control from the user end, we move to the many border restrictions that can be done on the listener level as well. The FTP listeners also come with the ability to induce Require Secure Control and Require Secure Data settings over the network. This way, a user will have to check these settings first when they are trying to make a login attempt. When these two options are enabled, then only FTPES secure connection can make the login attempt successfully. These settings are enforced before the individual setting from the user end is checked.


So this is what FTP is all about, the best file transfer protocol that one can use to send massive data files. Knowing a little more about FTP protocol makes it possible for you to make the best decision for your data transfer. The method of sending and storing your data should give you confidence. So you don’t have to worry about it all the time. In the end, it is best to take your time and choose the right FTP client for your data file transfer and server storage to eradicate all security concerns.

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