Troubleshooting SSH Issues in Vagrant (Oracle Linux 9)

This guide outlines the steps to resolve SSH authentication errors, such as "No supported authentication methods available," by properly configuring your Vagrantfile and managing SSH keys.

Step 1: Clean Up Vagrantfile

To avoid conflicts with legacy key paths, remove or comment out the following lines from your Vagrantfile:

# Remove these lines:
config.ssh.private_key_path = ["keys/vagrant_rsa", "~/.vagrant.d/insecure_private_key"]
config.vm.provision "file", source: "keys/vagrant_rsa.pub", destination: "~/.ssh/authorized_keys"

Step 2: Boot and Initial Connection

1. Boot up the Vagrant box as usual using vagrant up.

2. Use the native command vagrant ssh to connect to the box initially.

Step 3: Manual Key Configuration

Once connected to the box, follow these steps to use your own existing key pair:

• Navigate to the SSH directory: cd /home/vagrant/.ssh

• Open the authorized_keys file with a text editor.

• Add your Public Key to the file. Ensure the prefix matches the algorithm used:

• For RSA keys: ssh-rsa ...[key content]...

• For ED25519 keys: ssh-ed25519 ...[key content]...

• Save and exit the file.

Step 4: Local Agent Setup (Windows/Pageant)

To ensure a seamless connection from your host machine:

1. Convert your private key to .ppk format using PuTTYgen if you haven't already.

2. Load your .ppk private key into Pageant.

Common Error	Cause	Solution
PuTTY Fatal Error: No supported authentication methods available	The server rejects the key or the key is not provided to PuTTY.	Load the correct .ppk key in Pageant or PuTTY settings.
Pageant: Couldn't load this key (OpenSSH SSH-2 private key)	The key is in OpenSSH format instead of PuTTY's .ppk format.	Use PuTTYgen to load the OpenSSH key and "Save Private Key" as .ppk.

Once these steps are completed, you should be all set to connect via PuTTY or other SSH clients.