通过浏览器前端访问Google Cloud实例终端失败：无法连接SSH 22端口

Hey there, let’s work through this SSH port 22 issue you’re hitting with your Google Cloud instance—this is a super common pain point, but we can troubleshoot it step by step to get you connected.

1. Verify the Instance is Running & Has a Valid External IP #

• Head over to the GCP Console’s VM Instances page and double-check your instance status: it needs to be marked Running. If it’s stopped or terminated, start it up first.
• Confirm the instance has an external IP (either static or ephemeral). Ephemeral IPs can change if you stop/restart the instance, so refresh your browser SSH tab to pick up the latest IP if needed.

2. Check Firewall Rules Allow SSH Traffic (Port 22) #

Firewall blocks are the #1 culprit here:

• Go to VPC Network > Firewall Rules and look for the default default-allow-ssh rule. Make sure it’s:
  • Enabled (not disabled)
  • Targeted to all instances in network (or tagged with a label your instance has)
  • Set to allow ingress traffic on tcp:22
  • Source IP range includes your current public IP (or 0.0.0.0/0 for broad access, though not ideal for production)
• If the default rule is missing or broken, create a new one:
  • Direction: Ingress
  • Action on match: Allow
  • Targets: Select "Specified target tags" and add a tag like allow-ssh (then add this tag to your instance under "Tags" in its details page)
  • Source IP ranges: Enter your public IP (find it via curl ifconfig.me locally) or 0.0.0.0/0
  • Protocols and ports: Select "tcp" and enter 22

3. Ensure the SSH Service (sshd) is Running on the Instance #

If the firewall is open but SSH still fails, the sshd service might be down:

• Use the Serial Console (found in your instance’s details page under "Connect > Serial console") to access the instance without SSH:
  • Once logged in, check the service status with:

    sudo systemctl status sshd
    

  • If it shows "inactive (dead)", start it up and enable it to run on boot:

    sudo systemctl start sshd
    sudo systemctl enable sshd
    

• Double-check the sshd config file to make sure port 22 isn’t disabled:

  sudo nano /etc/ssh/sshd_config
  

  Look for the line Port 22—if it’s commented out (starts with #), remove the # and save the file, then restart the service with sudo systemctl restart sshd.

4. Validate SSH Key Configuration #

Browser SSH relies on keys stored in GCP metadata—let’s make sure those are set up correctly:

• Go to your instance’s details page > Metadata > SSH Keys tab. Check if your public key is listed here (format should be ssh-rsa AAAAB3NzaC1yc2E... your-username@domain).
  • If it’s missing, click "Add item" and paste your local public key (or let the browser generate a new one when you try to connect again).
• From the Serial Console, verify the key is present in your user’s authorized_keys file:

  cat ~/.ssh/authorized_keys
  

  If it’s not there, manually add it, then fix file permissions (critical for SSH to trust the keys):

  chmod 700 ~/.ssh
  chmod 600 ~/.ssh/authorized_keys
  sudo systemctl restart sshd
  

5. Rule Out Network or Resource Issues #

• Try connecting from your local terminal instead of the browser to get more detailed error messages:

  ssh your-username@instance-external-ip
  

  This might tell you if it’s a key issue, timeout, or permission problem.
• Check instance resource usage (CPU, memory) in the GCP Console’s Monitoring tab. If CPU is spiking to 100%, the instance might be too overloaded to respond to SSH—restart the instance to free up resources.
• If the instance was just created, wait 2-3 minutes for full initialization. Sometimes sshd takes a moment to start up during the first boot.

If none of these steps resolve the issue, you might need to create a new instance (copying over disk data if needed) or check for more advanced VPC configuration issues (like routing tables or NAT gateways), but 9 times out of 10, one of the above fixes will get you connected.

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