树莓派通过以太网SSH连接Ubuntu时权限拒绝的求助

Hey there, let's troubleshoot this SSH permission denied issue together—this is a pretty common snag, but we'll get your Pi connected to Ubuntu in no time. Let's go through the most likely fixes step by step:

1. Double-check the basics first #

• Make sure you're using the correct Ethernet IP address for your Raspberry Pi. On the Pi itself (connect a monitor or use serial access), run hostname -I to get its wired IP—don't accidentally use the WiFi IP if both are enabled.
• Confirm the Pi's username is actually pi. Some newer Raspberry Pi OS builds let you set a custom username during setup, so if you changed it, replace pi with your actual username in the SSH command.

2. Verify SSH is enabled and configured correctly on the Pi #

• First, check if the SSH service is running on the Pi:

  sudo systemctl status ssh
  

  If it shows active (running), great. If not, enable and start it with:

  sudo systemctl enable --now ssh
  

• Next, make sure password authentication is allowed in the SSH config:
  Edit the config file with sudo nano /etc/ssh/sshd_config, then find these lines:

  PasswordAuthentication yes
  ChallengeResponseAuthentication no
  

  Ensure PasswordAuthentication is set to yes (remove the # if it's commented out). Save the file (Ctrl+O, then Enter) and exit nano (Ctrl+X), then restart SSH to apply changes:

  sudo systemctl restart ssh
  

3. Don't overlook password typos! #

• Raspberry Pi passwords are case-sensitive, and when you type them into SSH, you won't see any characters (no asterisks, nothing)—this is normal. Double-check you're entering the exact password, then hit Enter.
• If you're unsure, log into the Pi locally first to confirm the password works.

4. Check Ubuntu's firewall settings #

• Ubuntu's default UFW firewall might be blocking incoming SSH connections. Try temporarily disabling it to test:

  sudo ufw disable
  

  If you can connect now, add a rule to allow SSH permanently, then re-enable the firewall:

  sudo ufw allow ssh
  sudo ufw enable
  

5. Bypass public key authentication (if it's interfering) #

• The error mentions publickey, which means your Ubuntu system might be trying to use SSH keys instead of a password, but the Pi doesn't have your public key stored. Force password-only authentication with this command:

  sudo ssh -o PreferredAuthentications=password -o PubkeyAuthentication=no pi@<your-pi-ip>
  

  This skips public key attempts and only uses password login.

6. Reset SSH on the Pi (last resort) #

• If nothing else works, completely reinstall the SSH server on the Pi to reset to default settings:

  sudo apt-get purge openssh-server
  sudo apt-get install openssh-server
  sudo systemctl enable --now ssh
  

  Then try connecting again.

内容的提问来源于stack exchange，提问作者user7910594