SSH Credentials Added Twice: Unable to Remote Connect via SSH on Ubuntu

Ubuntu is a popular Linux distribution widely used for server deployments and development environments. One of the most common ways to manage remote Ubuntu servers is via Secure Shell (SSH). However, encountering issues while trying to connect to an Ubuntu server using SSH can be frustrating. In this article, we will discuss a common issue where SSH credentials are added twice, preventing remote connectivity.

Context: SSH Credentials and Remote Connectivity

SSH is a cryptographic network protocol that allows secure remote access to servers. It is widely used for managing servers, transferring files, and executing commands remotely. The SSH protocol uses a pair of keys, a public key, and a private key, to authenticate the client and the server.

Adding SSH Credentials

To connect to an Ubuntu server via SSH, you need to add the server's public key to your local SSH known_hosts file or your ~/.ssh/authorized_keys file. This process is automated when you connect to a new server for the first time using SSH.

Issue: SSH Credentials Added Twice

In some cases, you might encounter an issue where your SSH credentials are added twice. This can prevent you from connecting to the server via SSH. Let's explore the possible causes and solutions for this issue.

Possible Causes

• ssh-keygen or ssh-copy-id command execution error.

• Duplicate SSH keys in your local SSH directory.

• Misconfigured SSH daemon on the server.

Solution: Execution Error

If you encounter an error while executing ssh-keygen or ssh-copy-id commands, try the following steps:

1. Delete the problematic key pair by running:

   rm ~/.ssh/id_rsa* rm ~/.ssh/id_rsa.pub

2. Generate a new key pair by running:

   ssh-keygen -t rsa -b 4096 -C "[email protected]"

3. Add the new public key to the server's authorized_keys file by running:

   ssh-copy-id user@server_ip

Solution: Duplicate SSH Keys

If you have duplicate SSH keys in your local SSH directory, you can remove them using the following steps:

1. List all the keys in your ~/.ssh directory:

   ls ~/.ssh

2. Remove the duplicate keys:

   rm ~/.ssh/ rm ~/.ssh/.pub

Solution: Misconfigured SSH Daemon

If the issue is caused by a misconfigured SSH daemon on the server, you can try the following steps:

1. Check the SSH configuration file:

   sudo nano /etc/ssh/sshd_config

2. Make sure the following lines are uncommented:

   • PermitRootLogin no
   • PasswordAuthentication yes
   • PubkeyAuthentication yes

3. Restart the SSH service:

   sudo systemctl restart ssh

In this article, we discussed the issue of SSH credentials being added twice, preventing remote connectivity to an Ubuntu server via SSH. We explored the possible causes and solutions for this issue, including execution errors, duplicate SSH keys, and misconfigured SSH daemons. By following the steps outlined in this article, you should be able to resolve the issue and successfully connect to your Ubuntu server via SSH.

References

• How to Set Up SSH Keys on Ubuntu 20.04
• How do I remove a SSH key from the agent?
• How to remove a public key from an authorized_keys file?