Password-less ssh logins using ssh keys

[dos2unix]

How to Set Up Password-less SSH Logins on Linux​

Introduction​

Password-less SSH logins can significantly streamline your workflow by allowing you to connect to remote servers without entering a password each time. This guide will walk you through generating SSH keys using ssh-keygen, copying the public key to the remote server using ssh-copy-id, and understanding the differences between RSA, DSA, and ECDSA keys.

Step 1: Generate SSH Key Pair​

First, you need to generate an SSH key pair on your local machine. This pair consists of a private key (which you keep secure) and a public key (which you share with the remote server).

1. Open your terminal.
2. Run the following command to generate a new SSH key pair:

3. ssh-keygen -t ecdsa -b 521 -C "[email protected]"
   ```

   • -t ecdsa: Specifies the type of key to create. ECDSA stands for Elliptic Curve Digital Signature Algorithm.
   • -b 521: Specifies the number of bits in the key. ECDSA keys are typically 256, 384, or 521 bits.
   • -C "[email protected]": Adds a label to the key.
   
   
   
4. You will be prompted to choose a location to save the key. Press Enter to accept the default location (~/.ssh/id_ecdsa).
5. You can also set a passphrase for an extra layer of security, but for password-less login, you can leave it empty by pressing Enter.

Step 2: Copy the Public Key to the Remote Server​

Next, you need to copy your public key to the remote server. This can be done easily using the ssh-copy-id command.

1. Run the following command, replacing remote_user and remote_host with your remote server's username and IP address or hostname:

   ssh-copy-id remote_user@remote_host
   ```

   
   
2. You will be prompted to enter the remote user's password. Once authenticated, your public key will be added to the remote server's ~/.ssh/authorized_keys file.

Step 3: Test Password-less SSH Login​

Now, you can test the password-less login by connecting to the remote server:

ssh remote_user@remote_host
```

You should be able to log in without being prompted for a password.

### Understanding SSH Key Types
There are different types of SSH keys you can generate, each with its own characteristics:

• RSA (Rivest-Shamir-Adleman): One of the first public-key cryptosystems and widely used for secure data transmission. RSA keys are generally considered secure and are the default type for SSH keys.
• DSA (Digital Signature Algorithm): An older standard for digital signatures. DSA keys are less common now due to security concerns and limitations in key size.
• ECDSA (Elliptic Curve Digital Signature Algorithm): Uses elliptic curve cryptography to provide the same level of security as RSA but with smaller key sizes, making it faster and more efficient.

### User-Specific Configuration
The steps above are user-specific and will not affect other users on either the local or remote system. Each user can generate their own SSH keys and configure password-less login independently.

### Conclusion
Setting up password-less SSH logins can greatly enhance your productivity by eliminating the need to enter passwords repeatedly. By following the steps outlined in this guide, you can securely connect to your remote servers with ease.

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[KGIII]

Hmm... You've done a bunch of these.

It is my opinion that they're worthy of being posted in the Tutorials sub-forum. I don't actually know if you have access to post in that sub-forum, but the above is my opinion.

If you do make a mistake, this is a forum and that means someone will chime in to correct you. Heck, they might even do so if you didn't make a mistake! ;-)