SSH jump host example with vagrant –

This time shows the tutorial two topics in one. The first topic is: “How an easy to configure SSH host jump”. The 2nd topic is: “Provisioning examples for Vagrant”.

Precondition

Vagrant installed
VirtualBox installed

File content

---
- name: jump_host
  box: centos/7
  ip: 192.168.100.10
  cpus: 1
  memory: 1024
- name: host_a
  box: centos/7
  ip: 192.168.100.20
  cpus: 1
  memory: 1024
- name: host_b
  box: centos/7
  ip: 192.168.100.30
  cpus: 1
  memory: 1024

Host *
  Compression yes
  AddressFamily inet
  Protocol 2
  ServerAliveInterval 60
  ServerAliveCountMax 30

Host jump_host
  HostName 192.168.x.x
  User testuser

Host host_*
  ProxyCommand ssh jump_host -W %h:%p
  User testuser

# -*- mode: ruby -*-

require 'yaml'

machines = YAML.load_file('machines.yml')
API_VERSION = "2"
KEY_LOCATION = "~/.ssh/id_rsa.pub"

Vagrant.require_version ">= 1.8.1"
Vagrant.configure(API_VERSION) do |config|

  # loop
  machines.each do |machines|
    # vm setup + provisioning
    config.vm.define machines["name"] do |machine|
      machine.vm.box = machines["box"]
      machine.vm.synced_folder ".", "/vagrant", disabled: true
      machine.vm.network "private_network", ip: machines["ip"]

      machine.vm.provider :virtualbox do |vb|
        vb.name = machines["name"]
        vb.cpus = machines["cpus"]
        vb.memory = machines["memory"]
        vb.gui = false
      end

      # provisioning: only jump_host
      if machines["name"] == 'jump_host'
        # prompt for interface
        machine.vm.network "public_network"

        machine.vm.provision "shell", inline: <<-SHELL
          cd /etc && sudo sed -i '/#AllowTcpForwarding yes/c\AllowTcpForwarding yes' ssh/sshd_config
          sudo systemctl restart sshd.service
          cd /etc && sudo grep -q 'host_a' hosts || echo '192.168.100.20  host_a' >> hosts
          cd /etc && sudo grep -q 'host_b' hosts || echo '192.168.100.30  host_b' >> hosts
        SHELL
      end

      # provisioning: all
      machine.vm.provision "file", source: KEY_LOCATION, destination: "/tmp/pub.key"

      machine.vm.provision "shell", inline: <<-SHELL
        sudo useradd testuser
        sudo mkdir /home/testuser/.ssh
        sudo touch /home/testuser/.ssh/authorized_keys
        sudo cat /tmp/pub.key > /home/testuser/.ssh/authorized_keys
        sudo rm -f /tmp/pub.key
        sudo chmod 0700 /home/testuser/.ssh
        sudo chmod 0644 /home/testuser/.ssh/authorized_keys
        sudo chown -R testuser:testuser /home/testuser/.ssh
      SHELL
    end
  end
end

Note: Replace values for HostName “192.168.x.x” by real IP from jump_host and KEY_LOCATION “~/.ssh/id_rsa.pub”!

Steps

# create and goto project
$ mkdir ~/Projects/JumpHostExample && cd ~/Projects/JumpHostExample

# create yaml file
$ vim machines.yml

# create Vagrantfile
$ vim Vagrantfile

# start Vagrant
$ vagrant up

# get IP from jump_host (for config)
$ ssh jump_host -c "ip addr show enp0s9"

# create or edit ssh config
$ vim ~/.ssh/config

# ssh into hosts via jump_host
$ ssh host_a
$ ssh host_b

– Softwaretester –

knowledge is power

SSH jump host example with vagrant