  IP Sub-Networking Mini-Howto

  Robert Hart,  hartr@interweft.com.au <mailto: hartr@interweft.com.au>
  v1.0, 31 March 1997
  : 翵 dannybox@nownuri.net <mailto: dannybox@nownuri.net>

    IP Ʈũ  ϴ    Ѵ.
    Ʈũ  Ȳ  ϴ A,B,C Ŭ
  Ʈũ ȣ ϴ ̴.

  ______________________________________________________________________

  

  1. Copyright
  2. Introduction
     2.1 ٸ  

  3. IP ȣ غ
     3.1 IP ȣ ȣƮ ƴ ̽  ̴.
     3.2 "Dotted Quads" ǥ IP ȣ
     3.3 IP ȣ Ŭ
     3.4 Ʈũ ȣ, ̽ ּҿ εĳƮ ּҵ
     3.5 Ʈũ ũ(network mask)

  4. ̶ ΰ?
  5.   ϳ?
  6. IP Ʈũ ȣ   
     6.1   ϱ
     6.2  ũ ϱ
     6.3  ũ Ʈũ ȣ ϱ

  7. 
     7.1  ̺

  ______________________________________________________________________

  1.  Copyright

  2.  Introduction

    IP Ʈũ ȣ   ,   ڿ
  ȿ  ̿ϴ  ߿.   ϳ IP Ʈũ
  ȣ  ٸ Ʈũ   ֵ ϳ IP Ʈũ
  ȣ     ϰ ִ.   ַ Ŭ C
  IP Ʈũ ȣ   ,  Ģ A, B Ŭ
  ϰ ȴ.

  2.1.  ٸ  

  IP ȣ  ڼϰ ⺻  ˷ִ    ִ.
  ڰ о ϴ 

  o  The Linux Network Administrators Guide
     <sunsite.unc.edu/LDP/LDP/nag/nag.html
     <http://sunsite.unc.edu/LDP/LDP/nag/nag.html>>.

  o  The Linux System Administration Guide <www.db.erau.edu/SAG/
     <http://www.db.erau.edu/SAG/>>.

  o  TCP/IP Network Administration by Craig Hunt, published by O'Reilly
     and Associates <www.ora.com/catalog/tcp/noframes.html
     <http://www.ora.com/catalog/tcp/noframes.html>>.

  3.  IP ȣ غ

  Ʈŷ ſ ϱ   IP ȣ  ⺻
    Ѵ.

  3.1.  IP ȣ ȣƮ ƴ ̽  ̴.

  ٵ  ߸  ⺻  и ؾ Ѵ. IP
  ȣ ȣƮ Ҵ  ƴϴ. IP ȣ ȣƮ Ʈũ
  ̽ Ҵ ̴. (κ ƴ) IP Ʈũ
  ϴ ǻͰ ϳ Ʈũ ̽ (׸ 
   ϳ IP ȣ ), ̷ 츸 ִ  ƴϴ.
  ǻͿ ٸ ̽  ( ʴ) Ʈũ
  ̽ . ׸   Ʈũ ̽  IP
  ȣ . ׷Ƿ 6 Ȱȭ ̽  ̽
  6 IP ȣ . ׸  IP ȣ  
  Ʈũ  ̽ Ҵȴ.   IP Ʈũ  
  Ȯ.

  ׷ ұϰ, κ  IP ȣ   밳 ȣƮ
  ּҸ Ѵ. ⼭ ؾ   ̰ ȣƮ ϴ
  Ư ̽  IP ȣ ٿ ĪѴٴ ̴. ͳݿ
  ϴ  ̽ (ټ ƴϴ) ϳ ̽
  Ƿ ϳ IP ȣ .

  3.2.  "Dotted Quads" ǥ IP ȣ

   IP ȣ  Ϳ (IPv4), IP ȣ 4(8Ʈ)
  Ʈ Ǿ  32Ʈ Ͽ  ǥѴ.   
    ǥ  ִ.(10 ǥ Ǵ). ׸ 
  б  IP ȣ 밳 "dotted quad"  ǥȴ. IP ȣ

  192.168.1.24  (.)  4 (10) ̴.

  4   8Ʈ Ʈ 10 ǥ ̰,  4 ڴ
  0 255 ǥ  ִ.(⼭ ؾ   0 ϳ
  ̹Ƿ  256 ̴)

   ȣƮ IP ȣ Ϻδ ȣƮ ġ Ʈũ ǥϰ, 
    ȣƮ(Ʈũ ̽)  ü ǥѴ. Ȯϰ 
   Ʈ  Ʈũ ID ǰ, Ʈũ ִ ȣƮ
  ϴµ   Ʈ  Ǵ° ϴ  Ʈũ 'Ŭ'
  ȴ.

  3.3.  IP ȣ Ŭ

  IP ȣ 3 Ŭ ִ.( : δ ƼĳƮ 
  Ŭ D Ƿ 4̴. Ŭ D 224.0.0.0-240.0.0.0 ּҸ
  )

  o  Ŭ A IP ȣ Ʈũ ϴµ   8
     Ʈ(dotted quad  ) ϰ,  24Ʈ( 
      dotted quad) Ͽ Ʈũ ̽ Ѵ.
     Ŭ A ּ   Ʈ ׻ 0̴ -  ù ° dotted
     quad  0 127  . ׷Ƿ ִ 128
     Ŭ A Ʈũ ȣ ϰ,  33,554,430  
     ̽ . ׷ Ʈũ 0.0.0.0(⺻ Ʈ(default
     route))  127.0.0.0 (  Ʈũ) Ư ǹ̸ 
       Ʈũ ϴµ  ʴ´. ׷Ƿ 126
     Ŭ A Ʈũ ȣ   ִ.

  o  Ŭ B IP ȣ Ʈũ ϴµ  16 Ʈ(
     2 dotted quad) ϰ  16Ʈ( 2 dotted
     quad) Ͽ ȣƮ ̽ Ѵ. Ŭ B ּҴ 
      Ʈ 2  Ʈ ׻ 10 .( :
     2 ǥϸ 10xxxxxx.xxxxxxxx .xxxxxxxx.xxxxxxxx). ׷Ƿ
      14Ʈ Ͽ 32767 Ŭ B Ʈũ  
     ִ. ׷Ƿ Ŭ B Ʈũ dotted quad ù ° Ʈ
      128 191  ,  Ʈũ ִ
     32,766 ̿  ̽ .

  o  Ŭ C IP ȣ ó 24Ʈ Ͽ Ʈũ ϰ,
      8Ʈ ȣƮ ̽ Ѵ. Ŭ C ּҴ 
     3 Ʈ ׻ 110̰ų dotted quad 192 255 
     . ׷Ƿ   Ŭ C Ʈũ ȣ
     4,194,303̰  254 ̽ . (ù°
     Ʈ 223 ū Ʈũ ̹  Ǿ ־  
     ) ϸ

     ___________________________________________________________________
        Ʈũ Ŭ            ù ° Ʈ ()
                A                           1  126
                B                         128  191
                C                         192  254
     ___________________________________________________________________

  ϴ Ʈũ ͳݿ Ǿ  ʴ ͵̴. 
  ּҵ

  o  Ѱ Ŭ A Ʈũ 10.0.0.0

  o  16 Ŭ B Ʈũ 172.16.0.0 - 172.31.0.0

  o  256 Ŭ C Ʈũ 192.168.0.0 - 192.168.255.0  
     '' Ʈũ ȣƮ ȥ ϱ   
     ̴.

  3.4.  Ʈũ ȣ, ̽ ּҿ εĳƮ ּҵ

  IP ȣ 3 ǹ̸   ִ.

  o  IP Ʈũ ּ(  Űü ϴ IP ̽ ׷
     -  ̴ ׸Ʈ ϴ  ͵). Ʈũ ȣ ׻
     ּ  ̽(ȣƮ) Ʈ 0 Ѵ. (Ʈũ
       ʴ)

  o  IP Ʈũ  εĳƮ ּ(ּҴ IP Ʈũ 
     ̽ ÿ '̾߱'ϱ  ȴ.). Ʈũ 
     εĳƮ ּҴ ̽(ȣƮ) Ʈ 1 Ѵ.(
     Ʈũ    ʴ )

  o  ̽ ּ(ȣƮ ִ ̴ ī峪 PPP ̽,
      ,   ).  ּҵ  0 ̰ų 1 츦
          ִ.  ȣƮ Ʈ  0̸ 
     ּҴ Ʈũ ּҰ ǰ, ȣƮ Ʈ  1̸  ּҴ
     εĳƮ ּҰ ȴ.

     ϸ

       Ŭ A Ʈũ 
       (1Ʈ Ʈũ ּ  3Ʈ ȣƮ ּ )
         10.0.0.0  ּ  ȣƮ Ʈ 0̹Ƿ Ŭ A Ʈũ ȣ̴.
         10.0.1.0   Ʈũ  ȣƮ ̴ּ.
         10.255.255.255  ּ  ȣƮ Ʈ 1̹Ƿ  Ʈũ
         εĳƮ ̴ּ.

     Ŭ B Ʈũ 
       (2Ʈ Ʈũ ּ  2Ʈ ȣƮ ּ )
         172.17.0.0  Ŭ B Ʈũ ȣ̴.
         172.17.0.1   Ʈũ  ȣƮ ̴ּ.
         172.17.255.255  Ʈũ εĳƮ ̴ּ.

     Ŭ C Ʈũ 
       (3Ʈ Ʈũ ּ  1Ʈ ȣƮ ּ )
         192.168.3.0  Ŭ C Ʈũ ȣ̴.
         192.168.3.42   Ʈũ  ȣƮ ȣ̴.
         192.168.3.255  Ʈũ εĳƮ ̴ּ.

   ȣƮ Ҵ  κ IP Ʈũ ȣ Ŭ C
  ̴ּ.

  3.5.  Ʈũ ũ(network mask)

  Ʈũ ũ ' ũ' ҷ  Ȯϴ. ׷ 밳
  Ʈũ ũ θ.

  ⼭ 츮    ִ  IP ּҰ IP Ʈũ
     ؼǴ Ʈũ ϸ, ̰
  Ʈŷ ¸ Ѵ.  ⺻ Ʈũ ũ 
  Ʈũ Ʈ '1'̰  ȣƮ Ʈ ũ̴:-

  o  Ŭ A Ʈũ ũ: 255.0.0.0

  o  Ŭ B Ʈũ ũ: 255.255.0.0

  o  Ŭ C Ʈũ ũ: 255.255.255.0 Ʈũ ũ 
     ؾ  ΰ ߿  ִ:-

  o  Ʈũ ũ   IP ȣ  ؼ 
     ģ.  (⼭ ''̶ Ư Ʈũ κ ǹѴ)

  o  Ʈũ ũ IP ȣ ƴϴ - ̰  IP ȣ 
       ؼǴ   ȴ.

  4.  ̶ ΰ?

  ̶ ϳ IP Ʈũ ּҸ    ϳ
  Ʈũ IP ּҰ      Ʈũ 
   ֵ ϴ ̴.

  ⼭ ߿ ܾ ''  ̴. ӽ ٱ 
    IP Ʈũ ԵǴ  Ʈũ  
  ٲ  ϳ IP Ʈũ̴. ؾ   ϳ IP
  Ʈũ  ϳ Ʈũ   ִٴ ̴.

  5.    ϳ?

  Ʈŷ ϴ  ˷ â IP Ծ ߴ 
  ư Ѵ. ̶ Ŭ A Ʈũ ȣ 鼭  鸸
  ȣƮ   ־   Ʈ ߴ.

   Ŵ Ʈ ִ  IP ǻ͵   Ʈũ
  Ǳ Ѵٸ û ƮȰ   ߻ 
  ߴ: Ʈũ ϴ  Ŵ  ⸣ Ͱ 
  Ǹ ̰, Ʈũ Ƹ ( Ȯ) ڽ Ʈ 
  ر ̾.   Ʈŷ ϸ: Ŭ A Ʈũ
  ȣ  Ʈũ е ̴.   
  Ʈũ     ̴.

  ̰ ۰ ϱ () Ʈũ  
  ǹѴ.  - и  ٸ Ʈũ  ̿ϸ鼭. ׷ 
   Ʈũ ̴, ū , FDDI, ATM  
   .  Ʈŷ ϴ ٸ :-

  o   Ʈ   Ʈĵ  Ǿ
       (̺ ̵)   ִ. Ʈŷ ϳ
     IP ȣ Ͽ IP ȯ泻 ̰͵ ϵ Ѵ.  
     ̷ ϵ   鿡  Ʈũ  IP
     ȣ(static IP number) ְ ;ϴ ISP(Internet Service
     Provider)鿡  ſ  ̷ ִ.

  o  Ʈũ Ʈ ɰ ӵ ϸ ų   .
     Ʈũ  ν  Ʈũ   Ʈ
       ǵ   ִ.   ü Ʈ ٿ
      Ʈũ 뿪  ʰ Ʈũ ӵ ų
      ִ.

  o  Ȼ 䱸  ٸ Ŭ ִ ڵ  Ʈũ
        - Ʈũ  ƴ  ׻ ٸ Ʈũ
     Ʈ ç  ִ. Ʈŷ  μ R & D μ
     Ʈũ Ʈ ĺ ϰ Ѵ.(Ȥ л 
     Ʈũ ĺ ϵ ϰų)!

  o   ȣȯ ʴ Ʈŷ  ϴ  ̿ϸ鼭, ̵
     ̿ ȣ  ʿѴ.

  6.  IP Ʈũ ȣ   

   IP Ʈũ ȣ   ʿ䰡 ִٰ ߴٸ
    ؾұ? Ʒ  ؾ  ϵ ڼ ϰ
  ִ.

  o    Ѵ.(Ʈũ  Ϳ  Ʈũ
     )

  o  ݿ  ̽ κ  󸶳 Ŀ 
     Ѵ.  ٽ ϸ    󸶳  IP ȣ
     ʿ  Ѵ.

  o  .  Ʈũ ũ Ʈũ ּҸ Ѵ.

  o  Ʈũ  ̽  IP ּҿ  Ʈũ
     ũ ҴѴ.

  o  . Ϳ Ʈ ϰ Ʈũ ̽ 
     Ʈ̿ Ʈ ׸/Ȥ ⺻ Ʈ Ѵ.

  o  ý ׽Ʈغ  ߰ߵǸ ģ. ׸ Ѽ .
     ^^     ϳ Ŭ C Ʈũ ȣ
     192.168.1.0    Ѵ.

      IP Ʈũ ִ 254 ̽(ȣƮ)   ְ,
     ݵ Ʈũ ڽ ǥ Ʈũ ȣ(192.168.1.0) ׸
     εĳƮ ּ (192.168.1.255) .

  6.1.    ϱ

    ؾ Ʈũ    յǵ 
  ̽ ȣ ǵ ϱ Ȯ ̺ Ʈ
  (infrastructure) ġؾ  ̴.

    پ κ(, ̵ ȯ ) ȣ Ҽ
  ִ Ŀ ʿ  𸥴.  и ̰Ϳ  ڼ 
  Ұϴ.  ʿϴٸ ̷ 񽺸 ϴ  Ʈũ
  /ġ    .    ׷ 
   Ǵ     ִ.  (comp.os.linux.networking
  <http://comp.os.linux.networking>   ׷)

  6.2.   ũ ϱ

      'Ҿ' IP ȣ  ̿
  Ÿ ʿϴ.    IP Ʈũ 2 ּҸ
  ̽(ȣƮ) ּҷ    ȴ - Ʈũ IP ȣ 
  ü εĳƮ ּ.   ϸ  
  Ʈũ ڽ ǥ  IP Ʈũ ȣ εĳƮ ȣ
  ʿ ϸ,  ȣ  IP Ʈũ   
   ȿ ̾ Ѵ.

  ׷Ƿ IP Ʈũ ΰ  иϴ  2 Ʈũ
  ּҿ ΰ εĳƮ ʿϴٴ ̹Ƿ, ̴ 
  'Ұ' ̽ (ȣƮ) ּҰ Ѵٴ  ǹѴ.
   4  Ʈũ ٸ  ڴ 8 ϰ ȴ.

     ݵ 4 IP ȣ Ǿ ִ.

  o  ΰ 밡 IP ̽ ȣ- Ѱ  Ʈũ 
      ̽  ̰  Ѱ  Ʈũ ̱ ȣƮ
      

  o  Ѱ Ʈũ ȣ

  o  Ѱ εĳƮ ּ

      ̷  ϴ IP ڸ ÿ鼭  Ʈũ
       ϴ   ٸ ̴. Ʈũ  ϳ
     ȣƮ ִٸ  Ʈũ ŵ ٸ Ʈũ  Ѵ.
     ׷  Ե  ݿ Ǵ  ü Ģ 
      ̴.

  ̷ IP Ʈũ ȣ Ȱ ũ⸦(   
  Ʈũ   ִ.)  2^n   
  ִ.(̶ n  IP Ʈũ ȣ ȣƮ Ʈ  ϳ
   ̴)

  ׷Ƿ ڽ Ʈũ ϴµ ̾ Ѵ - 
  ,  , Ȼ ѵ Ͽ ϸ 
  Ʈũ ڸ ̴   ؾѴ.

  6.3.   ũ Ʈũ ȣ ϱ

  IP Ʈũ    ϴ  Ʈũ ũ
  ̴.     IP Ʈũ ȣ  Ʈũ
  ũ ܼ Ʈũ ȣ  'Ʈũ Ʈ' '1'
  ϰ  ȣƮ Ʈ '0'  ̴.

  ׷Ƿ IP ȣ  Ŭ  ǥ Ʈũ ũ 
  .

  o  Ŭ A (8 Ʈũ Ʈ) : 255.0.0.0

  o  Ŭ B (16 Ʈũ Ʈ): 255.255.0.0

  o  Ŭ C (24 Ʈũ Ʈ): 255.255.255.0

      ϴ  ϳ Ȥ  ̻ 밡 ȣƮ
     Ʈ ͼ ̽  Ʈ Ʈũ Ϻη
     ؼϵ ϴ ̴.  ׷Ƿ Ʈũ ȣ ΰ 
      ؼ ù° ȣƮ Ʈũ ũ Ʈ 
     Ʈ '1' Ͽ Ѱ ȣƮ Ʈ ´.

  Ŭ C ּҿ  Ʈũ ũ
  11111111.11111111.11111111.10000000 Ǵ 255.255.255.128 ȴ.
  츮 캸 ִ Ŭ C Ʈũ ȣ 192.168.1.0 
  е   ɼ   ִ.

  ______________________________________________________________________
    No of      No of
    subnets    Hosts/net    netmask
    2            126        255.255.255.128 (11111111.11111111.11111111.10000000)
    4             62        255.255.255.192 (11111111.11111111.11111111.11000000)
    8             30        255.255.255.224 (11111111.11111111.11111111.11100000)
    16            14        255.255.255.240 (11111111.11111111.11111111.11110000)
    32             6        255.255.255.248 (11111111.11111111.11111111.11111000)
    64             2        255.255.255.252 (11111111.11111111.11111111.11111100)
  ______________________________________________________________________

  ̷, ó  鶧 ݵ Ʈũ ũ Ʈ
   ߿ ȣƮ Ʈ   ߿ ȣƮ Ʈ 
  ʿ .  ׷      ʴ´ٸ
   IP ȣ ſ ̻   ̴.   2
  ͼġ ʴ 츮 ν IP ȣ  ݿ ִ ˱Ⱑ
  ſ .  (ݸ ǻʹ    ߴ
     ̴)  Ʈũ ߴٸ 
   Ʈũ ּҿ εĳƮ ּҿ  Ʈũ IP
  ȣ  ˾ƾ Ѵ. ٽ ѹ    Ŭ C
  IP Ʈũ ȣ ϰ  ȣƮ ȣ ֵ ϰڴ.

  ______________________________________________________________________
    Netmask         Subnets Network B'cast  MinIP   MaxIP   Hosts  Total Hosts
    --------------------------------------------------------------------------
        128            2       0     127       1     126    126
                             128     255     129     254    126     252
      192            4       0      63       1      62     62
                              64     127      65     126     62
                             128     191     129     190     62
                             192     255     193     254     62     248
      224            8       0      31       1      30     30
                              32      63      33      62     30
                              64      95      65      94     30
                              96     127      97     126     30
                             128     159     129     158     30
                             160     191     161     190     30
                             192     223     193     222     30
                             224     255     225     254     30     240
  ______________________________________________________________________

   ̴ ó ̵ ڿ   ϱ 
  ȮϱⰡ ſ . Ʈŷ Ʒ  ڰ Կ
   밡 ȣƮ ּ ü ڰ Ѵٴ  ش.
   κ  е ȣƮ Ʈũ IP ȣ ׸
  Ʈũũ  Ҵ  ְ Ǿ.

  7.  

    ΰ Ʈũ ̽   PC ΰ(Ȥ
   ̻)   Ʈϱ  Ѵٸ Ŀο IP (IP
  Forwarding) ϵ ؾѴ.

  ______________________________________________________________________
            cat /proc/ksyms | grep ip_forward
  ______________________________________________________________________

  ̷    ̴.

  ______________________________________________________________________
    00141364 ip_forward_Rf71ac834
  ______________________________________________________________________

   ̷ ޽ Ÿ ʴ´ٸ  Ŀ IP 
  ǵ    ̹Ƿ Ŀ    ο Ŀ
  ġؾ Ѵ.     Ŭ C IP Ʈũ ȣ 192.168.1.0
  4    Ѵ.( 62 밡
  ̽/ȣƮ IP ȣ  ȴ). ׷ ̵  ΰ 
   ū ϳ Ʈũ  ϵ յ ̹Ƿ  
   Ʈũ ϰ ȴ.  

  ______________________________________________________________________
    Ʈũ        εĳƮ    Ʈũ              ȣƮ 
    192.168.1.0     192.168.1.63    255.255.255.192         62
    192.168.1.64    192.168.1.127   255.255.255.192         62
    192.168.1.128   192.168.1.255   255.255.255.128         124 (see note)
  ______________________________________________________________________

  :  Ʈũ 124 밡 Ʈũ ּҸ 
  (Ʈũ ũκ   ִ 126 ƴ) ̰
  ΰ ݿ  ' '̱ ̴. ٸ ΰ Ʈũ
  ִ ȣƮ 192.168.1.192 ' ʴ'  Ʈũ
  ּҷ ؼ ̴. ̿ ϰ 192.168.1.191  ' ʴ'
   εĳƮ ּҷ ؼ ̴.

  ׷Ƿ   192.168.1.191 192 Ʈũ ȣƮ ּҷ
  Ѵٸ    ΰ Ʈũ ϴ ӽŵ ̵
     ̴.  ̰  ߿ Ѱ  
  ش.  밡 ּҴ  ּ    ݿ 
  ȴٴ ̴.

  7.1.   ̺

    ϴ ǻͰ  Ʈũ ͷ Ѵٰ 
  غ.  ǻʹ    3 Ʈũ ̽ 
  ְ Ƹ ׹° ̽  ͳݿ Ǿ  ̴.
  ( ̽ '⺻ Ʈ' ̴.)    ǻͰ 
  ݿ   IP ּҸ ̽ Ѵٰ Ѵ. 
  Ʈũ ̽   Ǿ ̴.

  ______________________________________________________________________
    ̽      IP ּ         ݸũ
    eth0            192.168.1.1     255.255.255.192
    eth1            192.168.1.65    255.255.255.192
    eth2            192.168.1.129   255.255.255.128
  ______________________________________________________________________

  ̰Ϳ     ̴.

  ______________________________________________________________________
     ּ     Ʈ      Genmask         ̽
    192.168.1.0     0.0.0.0         255.255.255.192 eth0
    192.168.1.64    0.0.0.0         255.255.255.192 eth1
    192.168.1.128   0.0.0.0         255.255.255.128 eth2
  ______________________________________________________________________

   ݿ  ȣƮ ڽ IP ȣ Ʈũ ũ 
  Ǿ  ̴.(Ư Ʈũ ϵ)  ȣƮ
  Ʈũ  ̽  PC IP ּҸ ν, 
  ǻ͸ ڽ Ʈ/ͷ Ѵ.  Robert Hart Melbourne,
  Australia March 1997.

