FTP and SFTP for file transfer in Computer Networks - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the protocol used for secure file transfer.

Computer Networks

protocol = "[1]"  # Use this for secure file transfer

Drag options to blanks, or click blank then click option'

ASMTP

BHTTP

CFTP

DSFTP

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing FTP instead of SFTP for secure transfer.

SFTP stands for Secure File Transfer Protocol and is used for secure file transfers over a network.

2fill in blank

medium

Complete the sentence to describe the default port number for FTP.

Computer Networks

FTP_default_port = [1]

Drag options to blanks, or click blank then click option'

A80

B22

C21

D443

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing FTP port 21 with SSH port 22.

The default port number for FTP is 21.

3fill in blank

hard

Fix the error in the statement about SFTP's underlying protocol.

Computer Networks

SFTP_transfers_files_over = "[1]"

Drag options to blanks, or click blank then click option'

ASSH

BHTTP

CFTP

DSMTP

Attempts:

3 left

💡 Hint

Common Mistakes

Thinking SFTP uses FTP protocol.

SFTP works over the SSH protocol, which provides encryption and secure authentication.

4fill in blank

hard

Fill both blanks to complete the description of FTP and SFTP security.

Computer Networks

FTP is [1] while SFTP is [2]

Drag options to blanks, or click blank then click option'

Ainsecure

Bsecure

Cfast

Dslow

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up which protocol is secure.

FTP is insecure because it sends data unencrypted, while SFTP is secure due to encryption.

5fill in blank

hard

Fill all three blanks to complete the dictionary comprehension describing file transfer protocols.

Computer Networks

protocols = { [1]: [2] for [3] in ['FTP', 'SFTP'] }

Drag options to blanks, or click blank then click option'

Ap.lower()

Bp.upper()

Cp

Dprotocol

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names or methods.

This comprehension creates a dictionary with keys as protocol names and values as uppercase versions of those names. The variable p iterates over the list.

Practice

1. Which of the following statements correctly describes the main difference between FTP and SFTP?

easy

A. Neither FTP nor SFTP encrypt data during transfer.

B. SFTP encrypts data during transfer, while FTP does not.

C. Both FTP and SFTP encrypt data equally.

D. FTP encrypts data during transfer, while SFTP does not.

Solution

1. Step 1: Understand FTP security

   FTP is an older protocol that transfers files without encryption, making data vulnerable to interception.

2. Step 2: Understand SFTP security

   SFTP uses encryption to protect data during transfer, making it secure over untrusted networks.

3. Final Answer:

   SFTP encrypts data during transfer, while FTP does not. -> Option B

4. Quick Check:

   Encryption difference = SFTP encrypts, FTP does not [OK]

Hint: Remember: S in SFTP means Secure [OK]

Common Mistakes:

• Thinking FTP encrypts data
• Assuming both protocols are equally secure
• Confusing FTP with FTPS (which adds SSL)

2. Which of the following is the correct command to connect to a server using SFTP in a terminal?

easy

A. ftp [e-mail]

B. ssh [e-mail]

C. scp [e-mail]

D. sftp [e-mail]

Solution

1. Step 1: Identify SFTP command syntax

   The command to start an SFTP session is sftp [e-mail], which initiates a secure file transfer connection.

2. Step 2: Differentiate from other commands

   ftp is for FTP connections, ssh is for remote shell access, and scp copies files but is not an interactive file transfer session.

3. Final Answer:

   sftp [e-mail] -> Option D

4. Quick Check:

   SFTP command starts with 'sftp' [OK]

Hint: SFTP command always starts with 'sftp' [OK]

Common Mistakes:

• Using 'ftp' instead of 'sftp' for secure transfer
• Confusing SSH with SFTP command
• Using SCP which is not interactive

3. Consider this Python snippet using the paramiko library to upload a file via SFTP:

import paramiko
client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.connect('example.com', username='user', password='pass')
sftp = client.open_sftp()
sftp.put('local.txt', 'remote.txt')
sftp.close()
client.close()

What will happen when this code runs successfully?

medium

A. The file 'local.txt' is uploaded securely to 'remote.txt' on the server.

B. The file 'remote.txt' is downloaded to 'local.txt' on the client.

C. An error occurs because paramiko does not support SFTP.

D. The connection is made but no file transfer happens.

Solution

1. Step 1: Understand paramiko SFTP usage

   The code connects to the server using SSH, then opens an SFTP session to transfer files securely.

2. Step 2: Analyze the sftp.put method

   sftp.put('local.txt', 'remote.txt') uploads the local file named 'local.txt' to the server as 'remote.txt'.

3. Final Answer:

   The file 'local.txt' is uploaded securely to 'remote.txt' on the server. -> Option A

4. Quick Check:

   sftp.put uploads local to remote [OK]

Hint: sftp.put uploads local file to server [OK]

Common Mistakes:

• Confusing upload with download (put vs get)
• Thinking paramiko does not support SFTP
• Assuming no file transfer happens without error

4. A user tries to connect to a server using SFTP but gets an error: Permission denied (publickey). What is the most likely cause?

medium

A. The SFTP command is not installed on the client machine.

B. The user typed the wrong server address.

C. The server requires a public key for authentication, but the user did not provide one.

D. The file transfer was interrupted by network issues.

Solution

1. Step 1: Interpret the error message

   Permission denied (publickey) means the server expects a public key for login but did not accept any provided or none was given.

2. Step 2: Rule out other causes

   Wrong server address or missing SFTP command would cause different errors. Network interruption would not cause a permission denied error.

3. Final Answer:

   The server requires a public key for authentication, but the user did not provide one. -> Option C

4. Quick Check:

   Public key error means missing or wrong key [OK]

Hint: Permission denied (publickey) means missing SSH key [OK]

Common Mistakes:

• Assuming network issues cause permission denied
• Thinking the command is missing on client
• Confusing server address errors with authentication errors

5. You need to securely transfer multiple files from your local machine to a remote server over an untrusted network. Which approach is best to ensure security and efficiency?

hard

A. Use SFTP to transfer files directly with encryption.

B. Use FTP with a VPN connection to encrypt the data.

C. Use FTP without encryption because it's faster.

D. Use HTTP to upload files through a web browser.

Solution

1. Step 1: Evaluate security needs

   Since the network is untrusted, encryption is necessary to protect data during transfer.

2. Step 2: Compare transfer methods

   SFTP provides built-in encryption and secure authentication, making it ideal for secure file transfer. FTP alone is not secure, even with VPN it adds complexity. HTTP is not designed for secure file transfer.

3. Final Answer:

   Use SFTP to transfer files directly with encryption. -> Option A

4. Quick Check:

   SFTP = secure and efficient file transfer [OK]

Hint: Choose SFTP for secure file transfer over untrusted networks [OK]

Common Mistakes:

• Relying on FTP without encryption
• Assuming VPN always solves FTP security
• Using HTTP which is not meant for file transfer