private snippets

How to check if an IP address is private (IPv6, IPv4, cidr)

Tagged ip, private, validate, cidr, ipv4, ipv6  Languages ruby
require 'resolv'
require 'ipaddr'

class PrivateIP
  # https://en.wikipedia.org/wiki/Private_network#Private_IPv4_address_spaces
  IPV4_NETWORKS = %w[0.0.0.0/8
  10.0.0.0/8
  100.64.0.0/10
  127.0.0.0/8
  169.254.0.0/16
  172.16.0.0/12
  192.0.0.0/24
  192.0.0.0/29
  192.0.0.8/32
  192.0.0.9/32
  192.0.0.170/32
  192.0.0.171/32
  192.0.2.0/24
  192.31.196.0/24
  192.52.193.0/24
  192.88.99.0/24
  192.168.0.0/16
  192.175.48.0/24
  198.18.0.0/15
  198.51.100.0/24
  203.0.113.0/24
  240.0.0.0/4
  255.255.255.255/32
  224.0.0.0/24
  239.0.0.0/8].map { |cidr| IPAddr.new(cidr) }

  # https://en.wikipedia.org/wiki/Unique_local_address
  IPV6_NETWORKS = %w[fd00::/8
  fc00::/8
  0000:0000:0000:0000:0000:0000:0000:0000/64].map { |cidr| IPAddr.new(cidr) }

  class InvalidHost < ArgumentError; end

  # Examples:
  # private?('127.0.0.1') => true
  # private?('localhost') => true
  # private?('google.com') => false
  def self.private?(ip_or_host)
    address = IPAddr.new(ip_or_host)
    if address.ipv4?
      IPV4_NETWORKS.any? { |cidr| cidr.include?(ip_or_host) }
    elsif address.ipv6?
      IPV6_NETWORKS.any? { |cidr| cidr.include?(ip_or_host) }
    else
      false
    end
  rescue IPAddr::InvalidAddressError
    private_host?(ip_or_host)
  end

  # Example: private_host?('localhost') => true
  def self.private_host?(host)
    host_ips(host).any? do |type, ips|
      ips.any? { |ip| private?(ip) }
    end
  end

  # Example: host_ips('localhost') => {ipv4: ['127.0.0.1'], ipv6: []}
  def self.host_ips(host)
    ipv4 = Resolv::DNS.new.getresources(host, Resolv::DNS::Resource::IN::A)
    ipv6 = Resolv::DNS.new.getresources(host, Resolv::DNS::Resource::IN::AAAA)
    raise InvalidHost, "unknown host: #{host}" if ipv4.empty? && ipv6.empty?
    { ipv4: ipv4.map { |r| r.address.to_s },
      ipv6: ipv6.map { |r| r.address.to_s } }
  end
end
require 'test_helper'
require 'private_ip'

class PrivateIPTest < ActiveSupport::TestCase
  test "private?" do
    assert PrivateIP.private?('localhost')
    assert PrivateIP.private?('127.0.0.1')
    assert PrivateIP.private?('0.0.0.0')
    refute PrivateIP.private?('google.com')
    refute PrivateIP.private?('209.216.230.240')
  end

  test "private? (IPV6)" do
    assert PrivateIP.private?('fd7b:5886:20a0:11a0:1111:2222:3333:4444')
    assert PrivateIP.private?('::1') # Try http://[::1]:3000 in browser
    assert PrivateIP.private?('::')
    assert PrivateIP.private?('0:0:0:0:0:0:0:1')
  end

  test "private? (CIDR)" do
    PrivateIP::IPV4_NETWORKS.each do |cidr|
      assert PrivateIP.private?(cidr.to_s)
    end
    PrivateIP::IPV6_NETWORKS.each do |cidr|
      assert PrivateIP.private?(cidr.to_s)
    end
  end

  test "private_host?" do
    assert PrivateIP.private_host?('localhost')
    refute PrivateIP.private_host?('google.com')
  end

  test "host_ips" do
    assert_equal({ ipv4: ["127.0.0.1"], ipv6: [] }, PrivateIP.host_ips('localhost'))
    assert_equal({ ipv4: ["209.216.230.240"], ipv6: []}, PrivateIP.host_ips('news.ycombinator.com'))
  end

  test "host_ips (invalid)" do
    assert_raise PrivateIP::InvalidHost do
      PrivateIP.host_ips('https://google.com')
    end
    assert_raise PrivateIP::InvalidHost do
      PrivateIP.host_ips('127.0.0.1')
    end
    assert_raise PrivateIP::InvalidHost do
      PrivateIP.host_ips('::1')
    end
    assert_raise PrivateIP::InvalidHost do
      PrivateIP.host_ips('[::1]')
    end
    assert_raise PrivateIP::InvalidHost do
      PrivateIP.host_ips('::')
    end
  end
end

How to configure Kubernetes to pull images from a private Docker registry

Tagged docker, kubernetes, private, registry  Languages bash, yml

How to configure Kubernetes to pull images from a private Docker registry:

  • First configure Docker by following the steps outlined here:

https://snippets.aktagon.com/snippets/869-configure-docker-to-use-a-private-container-registry-using-a-self-signed-certificate

  • Verify that the Docker configuration contains the authentication information
sudo cat ~/.docker/config.json
{
    "auths": {
        "<registry-server>": {
            "auth": "<hash>"
        }
    },
    "HttpHeaders": {
        "User-Agent": "Docker-Client/18.09.4 (linux)"
    }
}
  • Base64 encode the config.json file
cat ~/.docker/config.json | base64 -w0 > config.base64.json
  • Create secret.yml and add the contents of config.base64.json to dockerconfigjson
apiVersion: v1
kind: Secret
metadata:
 name: registrypullsecret
data:
 .dockerconfigjson: <config.base64.json>
type: kubernetes.io/dockerconfigjson
  • Import the secret into Kubernetes
kubectl create -f secret.yml && kubectl get secrets
  • Test that the secret was imported into Kubernetes
kubectl get secrets

How to use private Github repositories with Bundler

Tagged bundler, git, github, private, repository  Languages bash

Does your Gemfile reference private Github repositories?

Option 1: ENV variable

export BUNDLE_GITHUB__COM=username:password
export BUNDLE_GITHUB__COM=<personal-oauth-token>:x-oauth-basic

Option 2: bundle config

bundle config https://github.com/bundler/bundler.git username:password

Option 3: ~/.git-credentials

echo 'https://user:pass@example.com' >> ~/.git-credentials

References https://github.com/rubygems/bundler/pull/3898 https://git-scm.com/docs/git-credential-store