Solutions to SSH Failed Permission Denied

Step 1: Diagnosing the Issue:

Use the Verbose mode of your SSH Client for proper and Detailed Error Message. It can be achieved by using -v or –v flags with your initial SSH command in your terminal. The message should look like this:

ssh -v username@hostname

For server-side error check the server error log for relevant error and entries for your connection error. You can check it by using a simple command on Debian Based System given below:

cd /
cd  /var/log/auth.log

Step 2: Checking for client-side Errors:

• Ensure that the user connecting to the remote server has proper and necessary permissions to access the server.
• Ensure proper Access Credentials for the SSH connection and cross verify it to be sure.
• Ensure that you have the latest SSH client installed in your system. On Debian based Systems, the command format should look like this for Debian Based Systems:

sudo apt update
sudo apt upgrade

After updating the SSH, restart it to apply the changes:

sudo systemctl restart ssh 

SSH, also known as Secure Shell, is a commonly used method for securely sending commands to a computer network over an unsecured computer network. It uses a cryptographic network protocol for authenticating and encrypting connections between devices. SSH allows for tunneling, or port forwarding, which allows the transfer of data packets across networks. It was developed as a replacement for other unsecured and vulnerable protocols like telnet for seamless solutions for remote access, file transfer, and command-line execution.

SSH operates generally on a client-server architecture, in which a server program accepts or rejects incoming connections, and a client program requests the server for information. Typically, the default port of SSH is 22.

SSH uses public key cryptography to authenticate the remote computer, or, if necessary, allows it to authenticate the server. When a public-private key is generated by the user, authentication is performed when the key pair is generated, and the session will be opened with any password input from the client.