Change Insecure Key to Custom Key on Vagrant

Vagrant changes the insecure key pair to randomly generated key on first setup by default. To Change the insecure key pair to your own key for secure login.

Setup multiple keys for e.g keys/private and keys/public.

mkdir -p ./keys/private ./keys/public
chmod 700 ./keys/private ./keys/public

for i in {1..3}; do
  ssh-keygen -t ed25519 -f ./keys/private/id_ed25519_vagrant$i -C "vagrant$i" -N ""
  mv ./keys/private/id_ed25519_vagrant$i.pub ./keys/public/
done

chmod 600 ./keys/private/*
chmod 644 ./keys/public/*

Define custom keys in order of priority:

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config.ssh.private_key_path = ["keys/private", "~/.vagrant.d/insecure_private_key"]

Disable automatic key generation and prevent vagrant from replacing the default insecure key with a new random key.

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config.ssh.insert_key = false

Copy the public key into the box

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config.vm.provision "file", source: "keys/public", destination: "~/.ssh/authorized_keys"

Disable password authentication (default creds: vagrant:vagrant)

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config.vm.provision "shell", inline: <<-EOC
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 sudo sed -i -e "\\#PasswordAuthentication yes# s#PasswordAuthentication yes#PasswordAuthentication no#g" /etc/ssh/sshd_config
3
 sudo service ssh restart
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EOC

vagrant up and connect the box with the private key.

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Vagrant.configure(2) do |config|
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  config.vm.box = "ubuntu/trusty64"
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  # ssh settings
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  config.ssh.insert_key = false
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  config.ssh.private_key_path = ["keys/private", "~/.vagrant.d/insecure_private_key"]
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  config.vm.provision "file", source: "keys/public", destination: "~/.ssh/authorized_keys"
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  config.vm.provision "shell", inline: <<-EOC
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    sudo sed -i -e "\\#PasswordAuthentication yes# s#PasswordAuthentication yes#PasswordAuthentication no#g" /etc/ssh/sshd_config
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    sudo service ssh restart
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  EOC
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end