SSH Key Authentication Setup Guide

Introduction

As your instructor for this course, I’ll guide you through setting up SSH key authentication for accessing our CS server (cs-ssh.uwf.edu). This method is both more secure and convenient than traditional password authentication, eliminating the need to enter your password each time you connect.

Key Concepts

Public Key Authentication

SSH key authentication uses a pair of cryptographic keys:

  • Public Key: Like a padlock that you can freely share. It’s placed on the server you want to access.

  • Private Key: Like the unique key that opens your padlock. Must be kept secret and secure on your computer.

Benefits

  • Increased security through cryptographic strength

  • No need to remember or type passwords

  • Protection against brute-force attacks

  • Automated secure file transfers and remote operations

Step-by-Step Instructions

1. Generate Your SSH Key Pair

Open a bash terminal and run:

ssh-keygen -t ed25519 -C "your_email@uwf.edu"

When prompted:

  • Press Enter to accept the default file location

  • Enter a passphrase (recommended) or press Enter twice for no passphrase

2. Verify Key Generation

Check that your keys were created:

ls ~/.ssh/

You should see two files:

  • id_ed25519 (private key)

  • id_ed25519.pub (public key)

3. Copy Public Key to Server

ssh-copy-id -i ~/.ssh/id_ed25519.pub your_username@cs-ssh.uwf.edu

4. Test Connection

Try connecting to the server:

ssh your_username@cs-ssh.uwf.edu

You should now connect without being prompted for a password.

Important Security Notes

  • Never share your private key

  • Keep your private key file secure (600 permissions on Unix-like systems)

  • Back up your private key securely

  • If using a passphrase, remember it can’t be recovered if forgotten

Troubleshooting

If you encounter issues:

  1. Check file permissions:

# On Linux/macOS
chmod 600 ~/.ssh/id_ed25519
chmod 600 ~/.ssh/id_ed25519.pub

  1. Verify public key installation:

ssh your_username@cs-ssh.uwf.edu "cat ~/.ssh/authorized_keys"

  1. Enable verbose SSH output for debugging:

ssh -v your_username@cs-ssh.uwf.edu

Support

If you continue to experience problems, please:

  • Check your key file locations and permissions

  • Ensure you’re using the correct username

  • Contact me during office hours or via email for assistance

You can now use this SSH key authentication to securely access our CS server for compiling and running your C++ and Java assignments without password prompts.