서브넷 계산 및 표현법, 192.168.0.0/32, CIDR

출처 : http://blog.naver.com/woodair?Redirect=Log&logNo=100025890392

 

-- CIDR 위키

http://en.wikipedia.org/wiki/CIDR

 

-- 서브넷 계산법

http://jodies.de/ipcalc

 

-- Subnet Mask Information

http://www.ripe.net/rs/ipv4/subnets.html

 

 

우선 192.168.4.0/24 는 192.168.4.0/255.255.255.0과 같습니다.

슬래쉬 뒤의 부분은 서브넷을 나타내는 것이구요. 문의하신 형태로 표현하는 것을 CIDR 포맷이라고 합니다. 아래 첨부한 테이블을 보시면 그 의미를 아실 수 있을겁니다.

 

 

Wherever in Firestarter a single numerical IP address can be inputted as part of a policy rule, a human readable hostname or a network identifier can also be used. This last form allows you to apply rules to a range of IP addresses.

 

A range is entered as either address/netmask, for example 192.168.0.1/255.255.255.0, or more commonly in CIDR format as 192.168.0.1/24.

 

The CIDR address consists of a standard dotted format 32-bit IP address and a postfix of the number of network identifying bits. This might sound confusing, and it is, but it is the only valid way to group IP addresses on the Internet.

Luckily you don't have to break out your pocket calculator to work out an IP range, as there exists many IP calculators online.

 

CIDR range notation examples
CIDR format	First host	Last host	Number of hosts
192.168.0.1/24	192.168.0.1	192.168.0.254	254
192.168.0.1/25	196.168.0.1	192.168.0.126	126
192.168.0.1/26	192.168.0.1	192.168.0.62	62
192.168.0.1/27	192.168.0.1	192.168.0.30	30
192.168.0.1/28	192.168.0.1	192.168.0.14	15
192.168.0.9/29	192.168.0.9	192.168.0.14	6
192.168.0.10/30	192.168.0.10	192.168.0.11	2
10.0.0.0/8	10.0.0.1	10.255.255.254	16777214
10.0.1.17/28	10.0.1.17	10.0.1.30	14

 

계산해보면.. 아래와 같다..

 

11111111.11111111.11111111.00000000  1(Network) : 24

       255.        255.       255.           0   255개호스트(255-0)

11111111.11111111.11111111.10000000   1 : 25

       255.        255.        255.       128   127개호스트(255-128)

11111111.11111111.11111111.11000000   1 => 26

       255.        255.        255.       192    63개호스트(255-192)

11111111.11111111.11111111.11100000   1 => 27

       255.        255.        255.       224    31개호스트(255-224)

11111111.11111111.11111111.11110000   1 => 28

       255.        255.        255.       240   15개호스트(255-240)

11111111.11111111.11111111.11111000   1 => 29

       255.        255.        255.       248   7개호스트(255-248)

11111111.11111111.11111111.11111100   1 => 30

       255.        255.        255.       252    3개호스트(255-252)

11111111.11111111.11111111.11111110   1 => 31

       255.        255.        255.       254    1개 호스트(255-254)