Use SSH-based tools to ensure the security of Linux network file transfer. Specific methods include: 1. Use SCP for simple encrypted transmission, support recursive copying and specifying SSH ports, but do not support breakpoint continuous transmission; 2. Use SFTP to achieve interactive reliable transmission, support breakpoint continuous transmission and remote file management; 3. Use Rsync over SSH to efficiently synchronize data, transfer only the change part, suitable for backup and unstable networks; 4. Follow best practices, including using SSH key authentication, disable root login, modifying the default port, verifying the host fingerprint, avoiding plaintext protocols and setting correct file permissions, thereby ensuring the security of transmission.

Transferring files over a network in Linux is a common task, but doing it securely is essential—especially when dealing with sensitive data or remote servers. Here's how to do it right, using built-in tools and best practices.

1. Use SCP for Simple, Encrypted File Transfers

SCP (Secure Copy Protocol) is one of the easiest and most widely used methods for securely copying files between Linux systems. It uses SSH for encryption, so no data is sent in plain text.

Basic syntax:

 scp /path/to/local/file username@remote_host:/path/to/remote/directory

Example:

 scp document.txt user@192.168.1.100:/home/user/

To copy from remote to local:

 scp user@192.168.1.100:/home/user/file.txt /local/destination/

Tips:

• Use -i to specify a private key if not using password authentication:

   scp -i ~/.ssh/id_rsa file.txt user@host:/destination/

• Use -r to copy directories recursively.
• Use -P (uppercase) to specify a non-default SSH port:

   scp -P 2222 file.txt user@host:/destination/

SCP is simple and secure, but lacks advanced features like recovering interrupted transfers.

2. Use SFTP for Interactive and Reliable Transfers

SFTP (SSH File Transfer Protocol) runs over SSH and provides an interactive file transfer environment. It's more feature-rich than SCP.

Connect to a remote server:

 sftp username@remote_host

Once connected, you can use commands like:

• put filename – upload a file
• get filename – download a file
• ls , cd , lls , lcd – navigate directories
• mput , mget – transfer multiple files

Example session:

 sftp user@192.168.1.100
sftp> cd /remote/dir
sftp> put report.pdf
sftp> get log.txt
sftp> exit

Advantages:

• Supports recovering interrupted transfers.
• Allows file management (rename, delete, etc.).
• More reliable for unstable connections.

Like SCP, SFTP uses SSH, so it's encrypted by default.

3. Use Rsync over SSH for Efficient and Secure Syncing

Rsync is ideal for synchronizing files and directories, especially when you want to minimize data transfer by only sending changes.

Basic secure syntax (using SSH):

 rsync -avz -e ssh /source/directory/ user@remote:/destination/

• -a : archive mode (preserves permissions, symlinks, etc.)
• -v : verbose output
• -z : compress data during transfer
• -e ssh : forces rsync to use SSH

Example:

 rsync -avz -e ssh ~/Documents/ user@192.168.1.100:/backup/Documents/

Why rsync is great:

• Only transfers changed parts of files.
• Can resume interrupted transfers with --partial .
• Excellent for backups and mirroring.
• Works well over slow or unreliable networks.

You can also combine it with SSH keys for passwordless automation.

4. Best Practices for Secure File Transfers

Even with encrypted tools, security depends on how you use them.

Follow these guidelines:

• ? Use SSH key authentication instead of passwords
  Generate SSH keys with ssh-keygen and copy the public key using ssh-copy-id . This reduces the risk of brute-force attacks.

• ? Disable root SSH login and use non-default ports
  Edit /etc/ssh/sshd_config :

   PermitRootLogin no
  Port 2222 # instead of 22

  Then restart SSH: sudo systemctl restart sshd

• ? Verify host authenticity
  Always confirm the server's SSH fingerprint on first connection to avoid man-in-the-middle attacks.

• ? Avoid insecure protocols like FTP, TFTP, or HTTP
  These send data in plain text. If you must use them, wrap them in a VPN or avoid sensitive data.

• ? Set proper file permissions after transfer
  Use chmod and chown on the destination to ensure files aren't world-readable.

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For most users, SCP is fine for one-off transfers, SFTP for interactive work, and rsync over SSH for syncing or backups. All are secure when SSH is properly configured.

Basically, stick to SSH-based tools, use key authentication, and keep your system updated—then your file transfers will be both fast and secure.

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