1
Write a post

Preparing & Securing Your Ubuntu Box for Deployment

Published Nov 18, 2015Last updated Feb 10, 2017
Preparing & Securing Your Ubuntu Box for Deployment

Background

Nowadays deployments have moved from bare-metal servers to virtual machines that are quicker to start, e.g. the one provided by Amazon, Digital Ocean, and OpenStack-based providers.
Thus, developers are no longer required to go through manual administration steps when configuring an Ubuntu box.

One of the ways you can get started is to use a ready-to-use pre-configured box images.

Another approach is to do an initial system restart and provision it according to your project needs with some provisioner tool like Ansible, Chef or Puppet.

If you decide to proceed with custom provisioning, your first step would be to perform basic box securing, as in some cases you are given with if you have a freshly-installed box with a root password.

Let me share with you quick recipe on initial box securing, which should be good for most of web deployments.

Challenges to Address

At the end of the article, we should be able secure an Ubuntu 14.04 LTS virtual server

  • configure firewall, allow only 22, 443 and 80 in.
  • register your public key(s) for deploy user
  • secure ssh to allow only authorization by keys.
  • put automatic process in play to ban open ssh port lovers from the internet.

Bootstrap Box Role

Ansible comes with a nice concept of reusing deployment snippets, called roles. So let's take a look,
what sa-box-bootstrap role does:

Configuration Options

Following variables might be overwritten:

  • root_dir - required, Ansible developer recipes repository
  • option_enforce_ssh_keys_login (true|false) - whenever to enforce ssh security
  • ufw_rules_default - default firewall policy. In most cases is not touched
  • ufw_rules_allow - set of inbound rules to be configured
  • sshd_config_lines - needed changes in SSHD config to secure the box.
  • option_file2ban - when true, file2ban package will additionally introduced
  • whitelistedips - set of ips that are considered safe - your office gateway, build server etc; To prevent you being accidentaly blocked

Step 1 : Set up a Firewall

1-st step install and configure ufw firewall:

- include: "{{root_dir}}/tasks_ufw.yml"

by default, following firewall rules apply (outgoing any, http https & ssh are allowed inside):

ufw_rules_default:
  - {
      policy: deny,
      direction: incoming
    }
  - {
      policy: allow,
      direction: outgoing
    }

ufw_rules_allow:
  - {
      port: 80,
      proto: tcp
     }
  - {
      port: 443,
      proto: tcp
    }
  - {
      port: 22,
      proto: tcp
     }

You can override these variables to match your needs.

Step 2: Create Deploy User

If you intend to work & provision this box, you most likely won't want to do it under the root.
Thus, your second step would be to create a deploy_user that is authorized by a set of provided SSH keys and allowed to become sudoer without a password (this is the base requirement for automated provisioning)

- include: "{{root_dir}}/use/__create_deploy_user.yml user={{deploy_user}} group={{deploy_user}} home=/home/{{deploy_user}}"
  when: deploy_user is defined

- name: SSH | Authorize keys
  authorized_key: user={{deploy_user}} key="{{ lookup('file', item) }}"
  when: deploy_user_keys is defined
  with_items: "{{deploy_user_keys}}"
  sudo: yes

You might define the user in your playbook, for example, in this way:

jenkins_user: jenkins
jenkins_authorized_keys:
  - "{{playbook_dir}}/components/files/ssh/vyacheslav.pub"

and later pass this as a parameter to a role:

roles:
   - {
       role: "sa-box-bootstrap",
       root_dir: "{{playbook_dir}}/public/ansible_developer_recipes",
       deploy_user: "{{jenkins_user}}",
       deploy_user_keys: "{{jenkins_authorized_keys}}"
     }

Step 3: Secure the SSH (optional)

- name: SSH | Enforce SSH keys security
  lineinfile: dest=/etc/ssh/sshd_config regexp="{{item.regexp}}" line="{{item.line}}"
  with_items: sshd_config_lines
  when: option_enforce_ssh_keys_login
  sudo: yes
  tags: ssh

If var option_enforce_ssh_keys_login is set to true, sshd config will be modified according to
sshd_config_lines rules. By default, it will use the v2 protocol, prohibit root login, and prohibit password authenticaton.

Step 4: Ban Suspicious Users from Guessing Your SSH User Access

If var option_fail2ban is set to true and the special tool fail2ban is installed, it will watch out for failure SSH logging attempts and ban intruders.
To prevent yourself from being accidentally blocked, it will be a good idea to whitelist your IPs. Both single IPs and network masks are supported, for example:

whitelistedips:
 - 127.0.0.1
 - 127.0.0.1/8

Creating Your Own Box Bootstrap Project

Let's prepare a basic bootstrap project that can be used in the future.
It includes following files:

  • bootstrap.sh - installs ansible alongside with dependences.
  • init.sh - initializes
  • .projmodules - fully compatible with .gitmodules git syntax and specifies a list of the dependencies that will be used by the playbook.
    In particular, it includes ansible--by default developer_recipes (repository with set of handy deployment recipes)--
    and an ansible role called sa-box-bootstrap responsible for box securing steps.
[submodule "public/ansible_developer_recipes"]
  path = public/ansible_developer_recipes
  url = git@github.com:Voronenko/ansible-developer_recipes.git
[submodule "roles/sa-box-bootstrap"]
        path = roles/sa-box-bootstrap
        url = git@github.com:softasap/sa-box-bootstrap.git
  • hosts - here's a list of the initial box credentials that were provided to you for the server
[bootstrap]
box_bootstrap ansible_ssh_host=192.168.0.17 ansible_ssh_user=your_user ansible_ssh_pass=your_password
  • box_vars.yml - set here specific environment overrides, like your preffered deploy user name and keys.
  • box_bootstrap.yml - here you put your box provisioning steps. Box securing is only the first step.
    In order, to override params for sa-box-bootstrap - pass the parameters like in example below.
- hosts: all

  vars_files:
    - ./box_vars.yml
  roles:
     - {
         role: "sa-box-bootstrap",
         root_dir: "{{playbook_dir}}/public/ansible_developer_recipes",
         deploy_user: "{{my_deploy_user}}",
         deploy_user_keys: "{{my_deploy_authorized_keys}}"
       }
       

The Code in Action

The code I'm using can be downloaded from the repository https://github.com/Voronenko/devops-bootstrap-box-template
Fork it, adjust parameters to your needs, and use.
Adjustments include: creation of a box_vars.yml file. You can override any of the above-mentioned variables.
The minimal required set is deploy_user and your public keys.

box_deploy_user: jenkins
box_deploy_authorized_keys:
  - "{{playbook_dir}}/components/files/ssh/vyacheslav.pub"

Ensure you have ansible (bootstrap.sh to install) and cloned roles directories (init.sh), then run setup.sh. If everything is configured correctly, you will see something like:

PLAY [all] ********************************************************************

GATHERING FACTS ***************************************************************
ok: [box_bootstrap]

TASK: [sa-box-bootstrap | Sets correctly hostname] ****************************
changed: [box_bootstrap]

TASK: [sa-box-bootstrap | debug var="ufw_rules_allow"] ************************
ok: [box_bootstrap] => {
    "var": {
        "ufw_rules_allow": [
            {
                "port": 80,
                "proto": "tcp"
            },
            {
                "port": 443,
                "proto": "tcp"
            },
            {
                "port": 22,
                "proto": "tcp"
            }
        ]
    }
}

TASK: [sa-box-bootstrap | UFW | Reset it] *************************************
ok: [box_bootstrap]

TASK: [sa-box-bootstrap | UFW | Configure incoming/outgoing defaults] *********
ok: [box_bootstrap] => (item={'policy': 'deny', 'direction': 'incoming'})
ok: [box_bootstrap] => (item={'policy': 'allow', 'direction': 'outgoing'})

TASK: [sa-box-bootstrap | UFW | Configure rules to allow incoming traffic] ****
ok: [box_bootstrap] => (item={'port': 80, 'proto': 'tcp'})
ok: [box_bootstrap] => (item={'port': 443, 'proto': 'tcp'})
ok: [box_bootstrap] => (item={'port': 22, 'proto': 'tcp'})

TASK: [sa-box-bootstrap | UFW | Configure rules to allow incoming traffic from specific hosts] ***
skipping: [box_bootstrap] => (item=ufw_rules_allow_from_hosts)

TASK: [sa-box-bootstrap | UFW | Enable it] ************************************
changed: [box_bootstrap]

TASK: [sa-box-bootstrap | Monit | Check if is installed] **********************
changed: [box_bootstrap]

TASK: [sa-box-bootstrap | Monit | libssl-dev dependency] **********************
changed: [box_bootstrap]

TASK: [sa-box-bootstrap | Monit | Download] ***********************************
changed: [box_bootstrap]

TASK: [sa-box-bootstrap | Monit | Install] ************************************
changed: [box_bootstrap]

TASK: [sa-box-bootstrap | debug msg="Creating deploy user {{my_deploy_user}}:{{my_deploy_user}} with home directory /home/{{my_deploy_user}}"] ***
ok: [box_bootstrap] => {
    "msg": "Creating deploy user jenkins:jenkins with home directory /home/jenkins"
}

TASK: [sa-box-bootstrap | Deploy User | Creating group] ***********************
changed: [box_bootstrap]

TASK: [sa-box-bootstrap | Deploy User | Creating user] ************************
changed: [box_bootstrap]

TASK: [sa-box-bootstrap | Deploy User | Check key presence] *******************
ok: [box_bootstrap]

TASK: [sa-box-bootstrap | Deploy User | Copy authorized_keys from {{ansible_user_id}}] ***
skipping: [box_bootstrap]

TASK: [sa-box-bootstrap | Deploy User | Set permission on authorized_keys] ****
skipping: [box_bootstrap]

TASK: [sa-box-bootstrap | Deploy User | Ensuring sudoers no pwd prompting] ****
changed: [box_bootstrap]

TASK: [sa-box-bootstrap | SSH | Authorize keys] *******************************
changed: [box_bootstrap] => (item=/home/slavko/labs/devops-bootstrap-box-template/components/files/ssh/vyacheslav.pub)

TASK: [sa-box-bootstrap | SSH | Enforce SSH keys security] ********************
ok: [box_bootstrap] => (item={'regexp': '^Protocol.*', 'line': 'Protocol 2'})
changed: [box_bootstrap] => (item={'regexp': '^PermitRootLogin.*', 'line': 'PermitRootLogin no'})
ok: [box_bootstrap] => (item={'regexp': '^RSAAuthentication.*', 'line': 'RSAAuthentication yes'})
ok: [box_bootstrap] => (item={'regexp': '^PubkeyAuthentication.*', 'line': 'PubkeyAuthentication yes'})
ok: [box_bootstrap] => (item={'regexp': '^ChallengeResponseAuthentication.*', 'line': 'ChallengeResponseAuthentication no'})
changed: [box_bootstrap] => (item={'regexp': '^PasswordAuthentication.*', 'line': 'PasswordAuthentication no'})
changed: [box_bootstrap] => (item={'regexp': '^MaxAuthTries.*', 'line': 'MaxAuthTries 3'})

TASK: [sa-box-bootstrap | SSH | Restart SSHD] *********************************
changed: [box_bootstrap]

TASK: [sa-box-bootstrap | Install base Ubuntu packages] ***********************
changed: [box_bootstrap] => (item=unzip,mc)

PLAY RECAP ********************************************************************
box_bootstrap              : ok=21   changed=13   unreachable=0    failed=0   

Finally, you'll have a secured box with the sudoer (deployed user) you specified, which is allowed to authorize only with keys you set. Root is not allowed to login. Only some inbound ports are allowed according to your rules.

Check with NMap and try to login:

ssh  192.168.0.17
Permission denied (publickey).

ssh -ldeploy_user 192.168.0.17
Welcome to Ubuntu 14.04.2 LTS (GNU/Linux 3.13.0-32-generic x86_64)
deploy_user@LABBOX17:~$

Points of interest

You can reuse this playbook to create your own box bootstrapping projects, and reuse the role to configure your environments in a quicker and more secure way with ansible

Discover and read more posts from Vyacheslav
get started
Enjoy this post?

Leave a like and comment for Vyacheslav

Be the first to share your opinion

Get curated posts in your inbox

Learn programming by reading more posts like this