Windows SSH: Permissions for 'private-key' are too open

Solution 1:

You locate the file in Windows Explorer, right-click on it then select "Properties". Navigate to the "Security" tab and click "Advanced".

Change the owner to you, disable inheritance and delete all permissions. Then grant yourself "Full control" and save the permissions. Now SSH won't complain about file permission too open anymore.

It should end up looking like this:

Solution 2:

Keys must only be accessible to the user they're intended for and no other account, service, or group.

• GUI:
  [File] Properties → Security → Advanced
  1. Owner: The key's user
  2. Permission Entries: Remove all except for the key's user
  3. Set key's user to Full Control
     
     
• Cmd:

  ::# Set Key File Variable:
      Set Key="%UserProfile%\.ssh\id_rsa"
  
  ::# Remove Inheritance:
      Icacls %Key% /c /t /Inheritance:d
  
  ::# Set Ownership to Owner:
      :: # Key's within %UserProfile%:
           Icacls %Key% /c /t /Grant %UserName%:F
  
      :: # Key's outside of %UserProfile%:
           TakeOwn /F %Key%
           Icacls %Key% /c /t /Grant:r %UserName%:F
  
  ::# Remove All Users, except for Owner:
      Icacls %Key% /c /t /Remove:g "Authenticated Users" BUILTIN\Administrators BUILTIN Everyone System Users
  
  ::# Verify:
      Icacls %Key%
  
  ::# Remove Variable:
      set "Key="
  

  
  
• PowerShell:

  # Set Key File Variable:
    New-Variable -Name Key -Value "$env:UserProfile\.ssh\id_rsa"
  
  # Remove Inheritance:
    Icacls $Key /c /t /Inheritance:d
  
  # Set Ownership to Owner:
    # Key's within $env:UserProfile:
      Icacls $Key /c /t /Grant ${env:UserName}:F
  
     # Key's outside of $env:UserProfile:
       TakeOwn /F $Key
       Icacls $Key /c /t /Grant:r ${env:UserName}:F
  
  # Remove All Users, except for Owner:
    Icacls $Key /c /t /Remove:g Administrator "Authenticated Users" BUILTIN\Administrators BUILTIN Everyone System Users
  
  # Verify:
    Icacls $Key
  
  # Remove Variable:
    Remove-Variable -Name Key
  

Solution 3:

In addition to the answer provided by ibug. Since i was using the ubuntu system inside windows to to run the ssh command. It still was not working. So i did

sudo ssh ...

and then it worked