ftp protocol port number Archives

Ever wondered how files get exchanged over the wires connecting different servers, clients, routers, and switches even if more than one network device is requesting different files from servers at the same time?

It is surprising to note that you get the same file you requested even if we have thousands and lacs of requesting devices, asking for different files at the same time, isn’t it?

FTP, also known as File Transfer Protocol can do wonders.

Transfer of files between computers (clients) and servers has become a crucial part of our everyday life in the current digital era. Be it downloading any book PDF or movie, uploading or downloading documents, is a reliable and efficient method to attain.

By the end, you’ll have a clear understanding of FTP protocol and its importance in networking.

What are the basics of FTP protocol?

The basics of the FTP protocol are as follows-

FTP is a standard File transfer protocol which works on APPLICATION LAYER and uses TCP which makes it a reliable protocol. As we don’t want to lose any bit of information, hence use of TCP is a better choice than using UDP as UDP is a connectionless protocol and it may lose some data packets and hence incomplete file transfer.

It works on the client-server model where the client initiates the connection and request file from the server: (PORT 20 and PORT 21).

(Further, we will discuss why it uses two ports)
Consider FTP as a courier service which delivers packages to your doorstep securely.

FTP acts as a mediator between the Client and the Server.

Why does FTP use two protocol numbers?

FTP uses two different protocol numbers because it operates using 2 different connections

Control Connection
Data Connection

Control Connection: –

It is responsible for maintaining a connection between the server and the client.
It handles the exchange of commands and responses between the client and server, allowing them to communicate and coordinate properly.
It remains open throughout the FTP session.
When a client initiates an FTP session, it connects to the server’s IP ADDRESS using PORT 21

Data Connection: –

Control Connection helps to establish and manage the connection, the actual transfer of data occurs over DATA CONNECTION.
It initiates on PORT 20

In this way, FTP is using Port 20 as well as Port 21.

How does FTP protocol work?

Let us discuss how the whole process of file transfer takes place from start to end.

1. Establishing Connection: – The client sends a request to a server using the domain name (or IP ADDRESS of the server) at PORT 21.

2. Once the connection is made, the server asks for authentication from the client, such as its username and password to ensure that only authorized users can access the server’s files.

3. Now the client can navigate the files stored in a server using FTP commands.

For example– The client used the get command followed by file name to download a file. The put command is used by the client to upload a file to the server.

4.The server sends some response codes to the client to indicate the status of the transfer.

For example– “150” is used to tell the client that the server is ready to send the file, and “226” denotes a successful transfer of the file to the client and closing of the data connection.

5. If the connection is no more needed and the client does not need a further connection to the server, the connection can be terminated using the “quit” command.

What are the common FTP commands?

User: This command sends the user authentication to the server.

Pass: This command sends the user password to the server

MKD: Make Directory: Creates a new directory on the remote server.

Bell: When any command completes, this command sounds like a bell.

Bye: It is used to terminate the FTP session and exit

CD: This command is used to change the directory on the remote system.

Delete: It is used to delete a file in the current remote directory.

Get: It is used to copy a file from the server to the client’s device.

Mdelete: It is used to delete multiple files at once.

Mget: It is used to copy multiple files from the remote machine to the local machine

Put: This command is used to copy a file from the user device to the server device

Pwd: This command is used to search the path name of the local directory on the remote system

Remote help: It is used to display the remote system information.

Rename: This command is used to rename the file of the system.

Send: It is used to send a file.

Type: It is used to set the file transfer type.

What are the common FTP replies?

150: File status okay, about to open data connection.

200: Command Okay

226: Closing data connection, File transfer successful

227: Entering passive mode.

230: User logged in.

250: Requested file action completed.

331: user name authenticated, need a password

421: Service not available

500: Syntax error

550: Requested action not taken; file unavailable.

What are some real-life uses of FTP protocol?

Let’s have a look at some important scenarios where FTP plays an important role-

Software updates: – Often companies distribute their software updates using FTP. This method ensures that users can easily download the latest version of their software and hence remove bugs, and get new features.

Online backup services: – Many online backup services use FTP for backing up and restoring data user data. It provides a convenient method for users to transfer their files to remote backup servers for data protection and recovery.

Use of Digital Asset: FTP is used by the organization to store digital assets like images, videos, and documents. It allows authorized users to consume these digital assets.

Web development: FTP is commonly used by web developers to upload website files to a web server. It makes it easy to transfer HTML, CSS, JavaScript, and other web-related files from their local machines to the server, making a website efficient to use by users all over the globe.

What are the advantages and disadvantages of the FTP protocol?

FTP protocol has some advantages and disadvantages.

ADVANTAGES: –

Wide Support: – FTP is supported by a wide range of operating systems and network devices making it highly compatible with every system. It can be used on Windows, MAC, and LINUX ensuring reliable file transfer between different systems.
User-friendly: – The simplicity of FTP commands makes it easy to operate and understand.
Resume capability: – FTP allows for resuming interrupted file transfers. If a connection is lost in between the file transfer, FTP ensures to resume the transfer from where it left off, and hence no need to restart the file transfer all over again.

DISADVANTAGES: –

Lack of encryption: – Data transferred using FTP are not secure. It is highly vulnerable to intercept and hence leads to unauthorized access. This limitation makes FTP unsuitable for transmitting sensitive or confidential information.
File corruption risk: – In some cases, FTP can result in file corruption during transfer. This can occur if there are some network issues and hence data packets are lost.

What are a few alternatives to the FTP protocol?

FTP is in used for decades and it solves our major problem of file transfer, but there are some better protocols which are more secure than FTP.

Secure File Transfer Protocol (SFTP): It used secure encryption of Secure Shell (SSH). It provides an additional layer of security ensuring the file is protected and encrypted.

File Transfer Protocol Secure (FTPS): It uses the Secure Socket layer (SSL) or Transport Layer Security (TLS) to encrypt the connection between client and server hence securing confidential information.

Conclusion

Besides a few disadvantages, FTP is a widely used protocol. It is simple yet effective working mechanism makes it easier to transfer even large files easily by following the client-server model and connecting between client and server using TCP, making FTP a reliable protocol.

We have already learned about various protocols in the networking ecosystem that perform various functions. The File Transfer Protocol (FTP) is an important networking protocol that enables the communication and transfer of files between two computers.

This transfer occurs on the Internet which belongs to the Transmission Control Protocol/ Internet Protocol (TCP/IP) suite. The FTP protocol is active in the Application Layer of the TCP/IP protocols.

There are two important counterparts in a typical FTP transaction, the local host and the remote host. The local host is usually the computer of an end-user who either wants to transfer, upload or download a file from the server. The server is referred to as the remote host that allows the transfer, upload and download of the files. This transaction of files occurs only if the user has been granted access to do so!

As we have already learned about the Hyper Text Transfer Protocol (HTML) whose function is similar to the FTP protocol which is to transfer files in a hypertext form. These files could be audio, video, or image.

In this blog, we will learn about the key features of the FTP protocol followed by the working of the FTP protocol. We will also cover how to use this protocol.

Note: If you haven’t read the previous blog of our CCNA 200-301 series, I highly recommend you do so.

Without any further delay, let us begin!

What is FTP?

The File Transfer Protocol (FTP) is a standard network protocol that is used to upload, download or transfer files from one computer to another. It allows expansive file transfer across various IP networks.

The following are the key features of the FTP protocol:

FTP is a standard Internet protocol that provides the sharing of files.
It transfers data with better control, quality, and reliability than HTML web services or email.
FTP uses a client-server model.
The FTP is most commonly used by Network Engineers in the process of upgrading an operating system of a network device.
The FTP protocol can also be used to download the newer version of iOS from a server and then reboot the device with the new iOS image.
FTP was standardized in 1971. This is even before the TCP/IP, therefore, FTP is a very old protocol.
The TCP ports used by FTP are 20 and 21.
There is no encryption in FTP similar to HTTP. Everything is sent in plain text including the username and password that is used for authentication.
FTPS (FTP over SSL/TLS) can be used for better security. Please note that the FTPS is an upgrade to FTP.
SSH File Transfer Protocol (SFTP) can also be used for greater security.
FTP does not only allow file transfers, but it also allows clients to look for file directories, add and remove directories, list files, etc.
The client sends FTP commands to the server to perform the above-mentioned functions.

How Does the FTP Work?

For the FTP protocol to work, the FTP client plays a very important role. It is a computer application that connects the user to remote servers using FTP protocol. The FTP client has the following three parts:

The user interface
Control process
Data transfer process

The server, on the other hand, has two major parts:

Control process
Data transfer process

For an FTP connection to be established, there are two unique communication channels:

Command channel:

This channel is responsible for initiating the instructions and response.

Data channel:

The data channel facilitates the distribution of the data.

The FTP uses two types of connections:

FTP Control Connection (TCP21):
It is established and used to send FTP commands and replies.
The client sends commands when it wants to perform an action, such as retrieving a file from the server, and then the server sends replies to acknowledge.
The actual data transfer does not occur using this FTP connection.
FTP Data Connection (TCP20):
When files and data are to be transferred, separate FTP data connections to TCP port 20 are established and terminated as required.

Now, all we need is an actual data connection to transfer the data. There are 2 different modes that can be used to establish an FTP data connection. These are:

Active Mode:
It is the default method of establishing FTP data connections.
In such a mode, the server initiates the TCP connection.
After the TCP connection is set up, the FTP data connection is established and the data can be exchanged.

Note: The FTP control connection is maintained throughout the whole process.

Passive Mode:
The client initiates the data connection in the FTP passive mode.
This is often the case when the client is behind a firewall which could block the incoming connection from the server.
The firewall permits the server’s replies but it would block the message if the server itself tries to TCP connection.

How to Use FTP?

There are mainly three approaches to how we can establish and use the FTP connection. These are:

Command-Line FTP:
This is the simplest method of establishing a TCP connection.
A command prompt is used.
This method is commonly used by Developers to transfer files.
Web browser:
We can also use a web browser to talk to the FTP server.
Sometimes, a user wants to access large directories on the server. This is where the web browser works the best.
However, this method is less reliable and slow.
FTP client:
This is the most popular method to use FTP.
It is easier to manage than the other methods.
It is also more powerful.
It gives more freedom than the FTP commands and web browser method.
It allows users to send large files.

Conclusion:

This marks the end of our FTP blog of CCNA course series. In this blog, we have learned what is FTP and how it works. Then, we also learned how to use the FTP connection. The bottom line is that the FTP is used to transfer files from one computer to another.

Stay tuned for learning more Protocols such as TFTP protocol in the CCNA series

Happy learning!

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What is FTP Protocol? – Explained