Find out if an IP is within a range of IPs

Question

How can you tell if an ip, say 62.156.244.13 is within the range of 62.0.0.0 and 62.255.255.255

Answer 1

Inspired by jdl’s answer, but with a Range:

class String
  def to_ip
    split(".").inject(0) { |s, p| (s << 8) + p.to_i }
  end
end

("62.0.0.0".to_ip.."62.255.255.255".to_ip).include?("62.156.244.13".to_ip)

Answer 2

>> require "ipaddr"
=> true
>> low = IPAddr.new("62.0.0.0").to_i
=> 1040187392
>> high = IPAddr.new("62.255.255.255").to_i
=> 1056964607
>> ip = IPAddr.new("62.156.244.13").to_i
=> 1050473485
>> (low..high)===ip
=> true

If you are given the network instead of the start and end addresses, it is even simpler

>> net = IPAddr.new("62.0.0.0/8")
=> #<IPAddr: IPv4:62.0.0.0/255.0.0.0>
>> net===IPAddr.new("62.156.244.13")
=> true

IPAddr will also work with IPv6 addresses

>> low = IPAddr.new('1::')
=> #<IPAddr: IPv6:0001:0000:0000:0000:0000:0000:0000:0000/ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff>
>> high = IPAddr.new('2::')
=> #<IPAddr: IPv6:0002:0000:0000:0000:0000:0000:0000:0000/ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff>
>> (low..high)===IPAddr.new('1::1')
=> true

Answer 3

I prefer this approach for converting the IP address to an integer for range comparison:

# n_ip("192.1.1.23") will return the number 192001001023
def n_ip(input)
  input.split(".").collect{|p| p.rjust(3, "0")}.join.to_i
end

def ip_in_range?(from, to, given)
  (n_ip(from)..n_ip(to).include?(n_ip(given))
end

Now you can check the value as follows:

>> ip_in_range?("192.168.0.0",  "192.168.0.255","192.168.0.200")
ip_in_range?("192.168.0.0",  "192.168.0.255","192.168.0.200")
=> true
>> ip_in_range?("192.168.0.0",  "192.168.0.255", "192.168.1.200")
ip_in_range?("192.168.0.0",  "192.168.0.255", "192.168.1.200")
=> false

The integer returned is not a 32 bit representation of the IP address. The logic will work for all valid IP addresses.

Answer 4

I would use this killer little function to convert the IP addresses into integers, and then compare those.

def ip_addr_in_range?(low, high, addr)
  int_addr = numeric_ip(addr)
  int_addr <= numeric_ip(high) && int_addr >= numeric_ip(low)
end

def numeric_ip(ip_str)
  ip_str.split('.').inject(0) { |ip_num, part| ( ip_num << 8 ) + part.to_i }
end

def test_ip_addr_in_range(low, high, addr, expected)
  result = ip_addr_in_range?(low, high, addr)
  puts "#{addr} #{(expected ? 'should' : 'should not')} be within #{low} and #{high}: #{(expected == result ? 'PASS' : 'FAIL')}"
end


test_ip_addr_in_range("192.168.0.0", "192.168.0.255", "192.168.0.200", true)
test_ip_addr_in_range("192.168.0.0", "192.168.0.155", "192.168.0.200", false)
test_ip_addr_in_range("192.168.0.0", "192.168.255.255", "192.168.100.200", true)
test_ip_addr_in_range("192.168.0.0", "192.168.100.255", "192.168.150.200", false)
test_ip_addr_in_range("192.168.255.255", "192.255.255.255", "192.200.100.100", true)
test_ip_addr_in_range("192.168.255.255", "192.255.255.255", "192.100.100.100", false)
test_ip_addr_in_range("192.168.255.255", "255.255.255.255", "200.200.100.100", true)
test_ip_addr_in_range("192.168.255.255", "255.255.255.255", "180.100.100.100", false)

$ ruby ip_range.rb
192.168.0.200 should be within 192.168.0.0 and 192.168.0.255: PASS
192.168.0.200 should not be within 192.168.0.0 and 192.168.0.155: PASS
192.168.100.200 should be within 192.168.0.0 and 192.168.255.255: PASS
192.168.150.200 should not be within 192.168.0.0 and 192.168.100.255: PASS
192.200.100.100 should be within 192.168.255.255 and 192.255.255.255: PASS
192.100.100.100 should not be within 192.168.255.255 and 192.255.255.255: PASS
200.200.100.100 should be within 192.168.255.255 and 255.255.255.255: PASS
180.100.100.100 should not be within 192.168.255.255 and 255.255.255.255: PASS

Answer 5

jdl's answer is good. I would make the in_range? function a one-liner:

def ip_addr_in_range?(low, high, addr)
  (numeric_ip(low) .. numeric_ip(high)) === numeric_ip(addr)
end

Answer 6

Don't make it any harder than it has to be.

def check_ip(ip)
  '62.0.0.0' < ip and ip < '62.255.255.255'
end

check_ip '62.156.244.13' #=> true

Edit: Or, if you're using Rails / ActiveSupport:

def check_ip(ip)
  ip.starts_with? '62'
end

check_ip '62.156.244.13' #=> true