root@generate-random:~/ip-addresses/ruby$ _

Generate Random IP Addresses in Ruby

Complete code tutorial with examples and best practices

Ruby

[ Code Example - Quick Summary ]

Language: Ruby

What: Generate random IPv4 and IPv6 addresses in Ruby using rand and IPAddr. Includes validation, RFC 1918 private ranges, and integration with Faker gem for Rails testing.

Try it: Use our interactive Ip-addresses generator or integrate this code into your Ruby application.

Generate random IPv4 and IPv6 addresses in Ruby using rand and IPAddr. Includes validation, RFC 1918 private ranges, and integration with Faker gem for Rails testing. Looking for other languages? Check our code examples in PHP , JavaScript , Python , Java , C# , C++ and Go or use our interactive web generator.

Ruby Code Example

require 'ipaddr'

# Generate random IPv4 address
def random_ipv4
  Array.new(4) { rand(0..255) }.join('.')
end

# Generate random private IPv4 (RFC 1918)
def random_private_ipv4
  ranges = [
    -> { "10.#{rand(0..255)}.#{rand(0..255)}.#{rand(0..255)}" },
    -> { "172.#{rand(16..31)}.#{rand(0..255)}.#{rand(0..255)}" },
    -> { "192.168.#{rand(0..255)}.#{rand(0..255)}" }
  ]
  ranges.sample.call
end

# Check if IP is private
def private_ip?(ip)
  return true if ip.start_with?('10.')
  return true if ip.match?(/^172\.(1[6-9]|2[0-9]|3[01])\./)
  return true if ip.start_with?('192.168.')
  return true if ip.start_with?('127.')
  return true if ip.start_with?('0.')
  false
end

# Generate random public IPv4
def random_public_ipv4
  loop do
    ip = random_ipv4
    return ip unless private_ip?(ip)
  end
end

# Generate random IPv6 address
def random_ipv6
  Array.new(8) { rand(0..0xFFFF).to_s(16).rjust(4, '0') }.join(':')
end

# Generate IPv4 with CIDR notation
def random_ipv4_with_cidr(min_cidr: 8, max_cidr: 32)
  ip = random_ipv4
  cidr = rand(min_cidr..max_cidr)
  "#{ip}/#{cidr}"
end

# Validate IP address using IPAddr
def valid_ip?(ip_string)
  IPAddr.new(ip_string)
  true
rescue IPAddr::InvalidAddressError
  false
end

# Check if IP is private using IPAddr
def private_ip_addr?(ip_string)
  ip = IPAddr.new(ip_string)
  ip.private?
rescue IPAddr::InvalidAddressError
  false
end

# Generate multiple IP addresses
def generate_ip_addresses(count = 10, type: :ipv4)
  count.times.map do
    type == :ipv6 ? random_ipv6 : random_ipv4
  end
end

# Using Faker gem (add to Gemfile: gem 'faker')
# require 'faker'
# ipv4 = Faker::Internet.ip_v4_address
# ipv4_private = Faker::Internet.private_ip_v4_address
# ipv4_public = Faker::Internet.public_ip_v4_address
# ipv6 = Faker::Internet.ip_v6_address

# Usage examples
puts "Random IPv4: #{random_ipv4}"
puts "Private IPv4: #{random_private_ipv4}"
puts "Public IPv4: #{random_public_ipv4}"
puts "IPv6: #{random_ipv6}"
puts "IPv4 with CIDR: #{random_ipv4_with_cidr}"
puts "Batch: #{generate_ip_addresses(5).join(', ')}"
puts "Is valid: #{valid_ip?('192.168.1.1')}"
puts "Is private: #{private_ip_addr?('192.168.1.1')}"

[EXPLANATION]

Ruby's Array.new(4) { rand(0..255) } creates 4 random octets, joined with dots. The built-in IPAddr class provides validation and the private? method for detecting RFC 1918 addresses. rand(0..255) generates inclusive random numbers. For IPv6, to_s(16) converts to hexadecimal and rjust(4, '0') zero-pads to 4 digits. The Faker gem offers convenient methods like ip_v4_address, private_ip_v4_address, and ip_v6_address for Rails and RSpec testing.

Expected Output

Random IPv4: 198.51.100.42
Private IPv4: 192.168.15.234
Public IPv4: 203.0.113.89
IPv6: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
IPv4 with CIDR: 198.51.100.42/24
Batch: 203.0.113.15, 198.51.100.89, 192.0.2.45, 198.51.100.123, 203.0.113.67
Is valid: true
Is private: true

Common Use Cases

Generate test data for Rails network applications
Create factory data with FactoryBot for IP fields
Mock API responses in RSpec integration tests
Test IP-based geolocation and routing features
Populate databases with realistic network test data

Important Notes

IPAddr is part of Ruby standard library, no gem installation needed
IPAddr#private? automatically detects RFC 1918, loopback, and link-local addresses
Faker gem integrates seamlessly with FactoryBot for Rails testing
SecureRandom can be used for cryptographically secure random bytes
Use IPAddr#mask for subnet calculations and CIDR operations