cidrinfo

Given an IP CIDR (e.g. 10.20.30.40/20), explain and illustrate the address, network, masks, and host address range.

Install

go get -u github.com/pda/cidrinfo

Usage example

IPv4

$ cidrinfo 10.20.30.40/20

          CIDR:  10.20.30.40/20

       IP bits:  32 (IPv4)        |-------------- 32 ---------------|
    IP address:  10.20.30.40      00001010 00010100 00011110 00101000

  Network bits:  20 (..../20)     |-------- 20 --------|
  Network mask:  255.255.240.0    11111111 11111111 11110000 00000000

     Host bits:  12 (32 - 20)                           |--- 12 ----|
     Host mask:  0.0.15.255       00000000 00000000 00001111 11111111

 Number of IPs:  4096 (2 ^ 12)
      First IP:  10.20.16.0       00001010 00010100 00010000 00000000
       Last IP:  10.20.31.255     00001010 00010100 00011111 11111111

IPv6

$ cidrinfo 2001:0db8:85a3:0000:0000:8a2e:0370:7334/64

          CIDR:  2001:0db8:85a3:0000:0000:8a2e:0370:7334/64

       IP bits:  128 (IPv6)                               |-------------------------------------------------------------------- 128 --------------------------------------------------------------------|
    IP address:  2001:db8:85a3::8a2e:370:7334             00100000 00000001 00001101 10111000 10000101 10100011 00000000 00000000 00000000 00000000 10001010 00101110 00000011 01110000 01110011 00110100

  Network bits:  64 (..../64)                             |-------------------------------- 64 ---------------------------------|
  Network mask:  ffff:ffff:ffff:ffff::                    11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

     Host bits:  64 (128 - 64)                                                                                                    |-------------------------------- 64 ---------------------------------|
     Host mask:  ::ffff:ffff:ffff:ffff                    00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111

 Number of IPs:  18446744073709551616 (2 ^ 64)
      First IP:  2001:db8:85a3::                          00100000 00000001 00001101 10111000 10000101 10100011 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
       Last IP:  2001:db8:85a3:0:ffff:ffff:ffff:ffff      00100000 00000001 00001101 10111000 10000101 10100011 00000000 00000000 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111

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	Made in Australia by Paul Annesley