执行gcloud alpha cloud-shell ssh时PuTTY提示“Server refused our key”求助

Hey Michael, let's work through this Cloud Shell SSH issue you're hitting. Since you can access Cloud Shell just fine through the web console, we know the instance itself is healthy—so the problem is almost certainly tied to your local authentication setup or how the gcloud alpha cloud-shell ssh command is handling keys. Here are some actionable steps to fix this:

• Force a full key regeneration and session re-authorization
  Sometimes even after clearing your .ssh folder, gcloud might not properly sync a new key pair with Cloud Shell. Run this command to overwrite any existing keys and re-establish a trusted session:

  gcloud alpha cloud-shell ssh --authorize-session --force-key-file-overwrite
  

  This ensures the key gcloud generates locally is explicitly authorized by the Cloud Shell server.

• Verify gcloud is using the correct SSH key file
  Try manually specifying the key path to eliminate any ambiguity. First, regenerate the compute SSH keys with:

  gcloud compute config-ssh
  

  Then connect using the newly generated key:

  gcloud alpha cloud-shell ssh --ssh-key-file=C:\Users\[YourUsername]\.ssh\google_compute_engine
  

  Replace [YourUsername] with your actual Windows user folder name.

• Fix PuTTY key format compatibility
  On Windows, gcloud often relies on PuTTY, which uses .ppk formatted keys instead of OpenSSH's default format. You can either:

  1. Use PuTTYgen to convert the google_compute_engine private key to a .ppk file, then specify it in the command:

     gcloud alpha cloud-shell ssh --ssh-key-file=C:\Users\[YourUsername]\.ssh\google_compute_engine.ppk
     

  2. Switch gcloud to use the OpenSSH client instead of PuTTY with this config change:

     gcloud config set ssh/ssh_executable openssh
     

     This avoids format mismatches entirely.

• Reset your Cloud Shell instance
  Sometimes the Cloud Shell server side might have cached invalid key data. In the web console's Cloud Shell, run exit to terminate the instance, then click the "Start Cloud Shell" button again to spin up a fresh instance. Try connecting locally once it's ready.

• Check for local network interference
  Local SSH agents (like Pageant) or firewall/antivirus tools can block key authentication. Close any running SSH agents temporarily, disable your firewall's network filtering for a test, then re-run the gcloud alpha cloud-shell ssh command. If this works, you'll need to add exceptions for gcloud or the SSH port.

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