如何实现Docker容器到服务器的SSH无密码认证？

Hey there! Let's get that passwordless SSH authentication working between your Docker container and the target server. Since you've already got the foundational setup done, here's a straightforward, step-by-step walkthrough tailored to your scenario:

1. 在Docker容器中生成SSH密钥对 #

Since your container runs with root privileges, we'll generate keys under the root user:

• First, access your running container (replace <container-name-or-id> with your actual container's name or ID):

  docker exec -it <container-name-or-id> bash
  

• Generate an RSA key pair—just press Enter for all prompts to use default settings:

  ssh-keygen -t rsa
  

This creates two files in /root/.ssh/: id_rsa (private key, keep this secure!) and id_rsa.pub (public key, which we'll share with the server).

2. 将容器的公钥添加到服务器的authorized_keys #

We have two easy methods to do this:

Method 1: Use ssh-copy-id (simplest, if you can SSH to the server with a password) #

From inside the container, run:

ssh-copy-id ramparn@173.33.255.20

When prompted, enter the password for the ramparn user on the server. This will automatically append your container's public key to the server's authorized_keys file.

Method 2: Manual copy (if ssh-copy-id isn't available) #

• Inside the container, print your public key and copy the entire output:

  cat /root/.ssh/id_rsa.pub
  

• Switch to your server's terminal, log in as the ramparn user:

  su - ramparn
  

• Ensure the .ssh directory exists with correct permissions:

  mkdir -p ~/.ssh && chmod 700 ~/.ssh
  

• Append the copied public key to authorized_keys (replace <your-container-public-key> with the text you copied):

  echo "<your-container-public-key>" >> ~/.ssh/authorized_keys
  

• Lock down permissions for authorized_keys (critical for SSH to accept it):

  chmod 600 ~/.ssh/authorized_keys
  

3. 测试无密码登录 #

From inside your Docker container, run:

ssh ramparn@173.33.255.20

You should be logged into the server as ramparn without entering a password!

Troubleshooting Common Issues #

• No ssh command in the container: Install the OpenSSH client first:

  apt update && apt install -y openssh-client
  

• Server rejects public key: Check the SSH config on the server:
  1. Edit /etc/ssh/sshd_config (as root on the server) and ensure these lines are uncommented:

     PubkeyAuthentication yes
     AuthorizedKeysFile .ssh/authorized_keys
     

  2. Restart the SSH service:

     sudo systemctl restart sshd
     

• Firewall blocking access: Make sure the server's port 22 is open to your container's IP address.

内容的提问来源于stack exchange，提问作者user9294423