Using SCP to Transfer Files with SSH keys Ubuntu: 3 Easy Steps

By Posted on

Using SCP to Transfer Files with SSH keys Ubuntu: 3 Easy Steps

This tutorial intends to teach you Using SCP to Transfer Files with SSH keys Ubuntu. As you must know, every Linux Administrator uses a different utility to access and manage the remote server. The most popular utilities are SCP and SSH. Let’s get familiar with these utilities and scp with ssh key to Transfer Files Ubuntu.

What is SCP and SSH?

SCP, which stands for secure copy protocol, is a command-line utility used for transferring files between servers in a secure mode. It is based on the SSH protocol. And SSH, which stands for the secure shell, is a network protocol that you can use to transfer data between an SSH client and SSH server in a secure channel.

Is SCP the same as SSH?

At this point, you may face the question of whether SCP and SSH are the same or not. The main difference between them is that SSH is used for logging into remote systems and controlling those systems, while SCP is used for transferring files among remote computers in a network.

How to Use SCP with SSH key?

You can use the SCP command to transfer files from a remote server with an encrypted SSH tunnel. Also, you can use SSH keys to make your transfer action more secure. To do this, you can follow the steps below to learn Using SCP to Transfer Files with SSH keys Ubuntu.

At this point, we want to use SCP to transfer files with SSH keys (PEM file). PEM file format is mostly used to store cryptographic keys. Now you must have access to your Ubuntu server as a root user, and generate a Pem file, and follow the steps below for Using SCP to Transfer Files with SSH keys Ubuntu.

In this guide, we use Ubuntu 22.04 server to show the guide steps for Using SCP to Transfer Files with SSH keys Ubuntu.

Step 1 – Generate SSH Keys and a PEM File on Ubuntu

The first step is to generate the SSH keys on Ubuntu. To do this, you can run the command below:

ssh-keygen -t rsa -b 2048

When you run the above command, you will be asked to enter a file name for your key and set a passphrase for your file. Here we named our file scp_server, you can choose your desired name. When you are done, you will get the following output:

At this point, you can list your SSH key files with the following command:

ls

Then, you should see that you can two SSH key files (public and private):

**Output**
scp_server  scp_server.pub

Next, you must generate a Pem file with your Private SSH key by using the following command:

cp -p scp_server scp_server.pem

Now when you list the files, you must see the pem file is generated too.

ls
**Output**
scp_server  scp_server.pem  scp_server.pub

Step 2 – Copy the Ubuntu SSH Public Key to the Remote Server

At this point of Using SCP to Transfer Files with SSH keys Ubuntu, you must copy the public key to the server you want to access. To do this, you can use the following command:

ssh-copy-id -i public-key username@remote-server-ip

For example, our public key is scp_server.pub, and remember to replace the username and IP with the remote server you want to access.

You will be asked to enter the remote server’s password. You should get the following output:

**Output**
Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'root@...'"
and check to make sure that only the key(s) you wanted were added.

Then, in the Ubuntu local machine, set the correct permissions for the Pem file with the following command:

chmod 400 scp_server.pem

You can verify everything is working fine by using the command below:

ssh -i scp_server.pem username@remote-server-ip

Enter the passphrase of the SSH key file you have generated, then, you should see:

Now that you have logged in successfully with the Pem file, you can start Using SCP to Transfer Files with SSH keys Ubuntu.

Step 3 – Use the SCP command with SSH keys (Pem File) To Transfer Files

At this point, you can easily use the SCP command to transfer files with SSH keys on Ubuntu. You just want to specify the path to the Pem file:

scp -i /path/to/file.pem /path/to/local/file username@remote.server.com:/path/to/remote/destination

For example, to copy a single file with a Pem file to a remote server, you can run the command below:

scp -i scp_server.pem test-file username@remote-server-ip:/home/username/

Also, you can copy an entire directory by using the -r option. For example:

scp -i scp_server.pem -r Test-Directory username@remote-server-ip:/home/username/

Next, if you want to transfer a file from the remote server to the local machine, you can use the following syntax:

scp <options> remote-server@ip-addres:/path-to-file <folder_local_system>

That’s it, you are done. With this option, you can easily transfer files securely.

Conclusion

At this point, you have learned a secure way to transfer files between a local and remote machine. You can easily generate a Pem file and use SCP with this file to transfer the data between servers. Hope you enjoy this guide on Using SCP to Transfer Files with SSH keys Ubuntu.

You may be interested in these articles:

Using the ssh-copy-id Command

Web-based SSH Client To Linux

How To SSH into a Windows Machine

[SOLVED] SSH connection reset by peer error

Alternative Solutions for Secure File Transfer

While SCP with SSH keys is a robust method, here are two alternative solutions for transferring files securely in Ubuntu, each with its own benefits and use cases:

1. Using Rsync over SSH

Rsync is a powerful utility for synchronizing files and directories between two locations. When combined with SSH, it offers a secure and efficient way to transfer files, especially for incremental backups or large datasets.

Explanation:

Rsync’s key advantage is its ability to only transfer the differences between files, rather than the entire file, which can significantly reduce transfer times and bandwidth usage. When using Rsync over SSH, the connection is encrypted, ensuring secure data transmission. This is a reliable solution for Using SCP to Transfer Files with SSH keys Ubuntu.

Code Example:

To use Rsync over SSH, you can use the following command:

rsync -avz -e "ssh -i /path/to/your/private_key" /path/to/local/directory/ username@remote-server-ip:/path/to/remote/destination/

Breakdown:

  • rsync: The rsync command itself.
  • -avz: Options for archive mode (preserves permissions, ownership, etc.), verbose output, and compression.
  • -e "ssh -i /path/to/your/private_key": Specifies that SSH should be used as the transport protocol, using the specified private key for authentication.
  • /path/to/local/directory/: The path to the local directory you want to transfer. The trailing slash is important; without it, rsync will create a subdirectory named after the source directory on the destination.
  • username@remote-server-ip:/path/to/remote/destination/: The destination in the format username@server:path.

Benefits:

  • Efficiency: Only transfers changed data, saving bandwidth and time.
  • Security: Uses SSH for encryption.
  • Versatility: Can be used for backups, mirroring, and general file synchronization.
  • Resilience: If the transfer is interrupted, rsync can resume from where it left off.

2. Using SFTP (Secure File Transfer Protocol)

SFTP is a secure file transfer protocol built directly into SSH. It provides a command-line interface similar to FTP, but with the added security of SSH encryption.

Explanation:

SFTP provides an interactive shell for navigating the remote file system and transferring files. It’s suitable for scenarios where you need more control over the file transfer process than a simple SCP command offers. With SFTP, you can list directories, change permissions, and perform other file management tasks securely.

Code Example:

  1. Connect to the remote server:
sftp -i /path/to/your/private_key username@remote-server-ip
  1. Once connected, you can use SFTP commands:
  • ls: List files in the current remote directory.
  • cd: Change the current remote directory.
  • get local_file: Download a file from the remote server to your local machine.
  • put remote_file: Upload a file from your local machine to the remote server.
  • exit: Close the SFTP connection.

Example SFTP session:

sftp> ls
file1.txt  file2.txt  directory1
sftp> get file1.txt
Fetching /home/user/file1.txt to file1.txt
sftp> put local_file.txt
Uploading local_file.txt to /home/user/local_file.txt
sftp> exit

Benefits:

  • Interactive: Provides a command-line interface for file management.
  • Secure: Uses SSH for encryption.
  • Familiarity: The command-line interface is similar to FTP, making it easy to learn.
  • Flexibility: Supports a wide range of file operations, including listing directories, changing permissions, and resuming interrupted transfers.

Both Rsync over SSH and SFTP provide secure and efficient alternatives to SCP for transferring files with SSH keys in Ubuntu. The choice of which method to use depends on your specific needs and preferences. Rsync is excellent for synchronization and incremental backups, while SFTP offers a more interactive file management experience.

Related posts: