There is a known problem with the interaction of Vagrant and recent versions of Windows where the system (Windows) OpenSSH client is installed (for example: https://github.com/hashicorp/vagrant/issues/13027 ).
Most advice suggests telling Vagrant to use it’s own internally shipped SSH client, but I’ve found that to be buggy (particularly its handling of Ctrl+C). Windows’ own SSH client only complains because of the open ownership of the SSH private key generated by Vagrant.
The following PowerShell (which I keep as fix_ssh.ps1 in the root of my Vagrant-powered codebase) resolves the problem. Credit to https://superuser.com/a/1329702 for the PS method of fixing the permissions.
Write-Host "Trying to retrieve Vagrant SSH details ... (this may take a moment)"
$VagrantSshKey = "$(vagrant ssh-config | Select-String -Pattern "^ IdentityFile ")".Split(" ")[3]
If (!$VagrantSshKey.EndsWith("private_key")) {
Write-Host "Could not determine Vagrant private SSH Key location. Unable to proceed."
Exit 1
}
Write-Host "Key location is: $VagrantSshKey"
Write-Host "Fixing key permissions..."
# Remove Inheritance:
icacls $VagrantSshKey /c /t /Inheritance:d
# Set Ownership to Owner:
icacls $VagrantSshKey /c /t /Grant:r ${env:UserName}:F
# Remove All Users, except for Owner:
icacls $VagrantSshKey /c /t /Remove:g Administrator "Authenticated Users" BUILTIN\Administrators BUILTIN Everyone System Users
# Verify:
icacls $VagrantSshKey
Write-Host "Fixed SSH private key permissions."