Linux IP Masquerade mini HOWTO ¤¤Ä¶ª© : ­I´ºª¾ÃÑ
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2. ­I´ºª¾ÃÑ

2.1. ¤°»ò¬O IP Masquerade?

IP Masquerade ¬O Linux µo®i¤¤ªº¤@ºØºô¸ô¥\¯à¡D¦pªG¤@¥x Linux ¥D¾÷¨Ï¥Î IP Masquerade ¥\¯à³s½u¨ìºô»Úºô¸ô¤W¡A¨º»ò±µ¤W¥¦ªº¹q¸£¡]¤£½×¬O¦b¦P¤@­Ó°Ï°ìºô¸ô¤W©ÎÂǥѼƾھ÷³s½u¡^¤]¥i¥H±µÄ²ºô»Úºô¸ô¡A§Y¨Ï¥¦­Ì¨S¦³Àò±o¥¿¦¡«ü©wªº IP ¦ì§}¡D

³o¨Ï±o¤@¨Ç¹q¸£¥i¥HÁôÂæb¹h¹D(gateway) ¨t²Î«á­±¦s¨úºô»Úºô¸ô¦Ó¤£³Qµo²{¡A¬Ý°_¨Ó´N¹³¥u¦³³o­Ó¨t²Î¦b¨Ï¥Îºô»Úºô¸ô¡D¬ð¯}³]©w¨}¦nªº°°¸Ë(masquerade)¨t²Î¤§¦w¥þ¨¾Å@À³¸Ó·|¤ñ¬ð¯}¨}¦nªº«Ê¥]¹LÂo¦¡¨¾¤õÀð(packet filter firewall)¨Ó±o§ó¥[§xÃø¡]°²³]¨âªÌ¤§¤¤³£¨S¦³¿ù»~¡^¡D

2.2. ²{ªp

IP Masquerade ¤´µM¦b¹êÅç¶¥¬q¡DµL½×¦p¦ó¡A®Ö¤ß±q 1.3.x ¶}©l¤w¸g¤º«Ø³o¶µ¤ä´©¡D³\¦h­Ó¤H¬Æ¦Ü¤½¥q¥¿¦b¨Ï¥Î¥¦¡A¦Ó¦³º¡·Nªºµ²ªG¡D

ÂsÄýºô­¶¥H¤Î»·ºÝñ¤J(telnet)¤w¸g¦³¦^³øªí¥Ü¥i¥H¦b IP Masquerade ¤W¹B§@¡DÀÉ®×¶Ç¿é(FTP)¡Aºô¸ô¥æ½Í(IRC) ¥H¤Î²âÅ¥ Real Audio ²{¦b¥i¥H¸ü¤J¬Y¨Ç¼Ò²Õ°t¦X¡D¨ä¥¦ªººô¸ô¸ê®Æ¬y­µ°T (streaming audio) ¹³¬O True Speech ¥H¤Î Internet Wave ¤]¯à¹B§@¡D¤@¨Ç¶l»¼¦Cªí¤¤ªº¨Ï¥Î¹Ù¦ñ¬Æ¦ÜÁÙ¹Á¸Õ¹Lµø°T·|ij³nÅé¡D Ping ²{¦b°t¦X·sªñ¥i¥H¨ú±oªººô»Úºô¸ô±±¨î°T®§¨ó©w(ICMP)­×¸ÉÀɤ]¯à¹B§@¡D

§ó§¹¾ãªº¤ä´©³nÅé¦Cªí½Ð°Ñ¦Ò 4.3 ¸`¡D

IP Masquerade ¦b¼ÆºØ¤£¦Pªº§@·~¨t²Î¤Î¥­»O¤W»P '«È¤áºÝ¾÷¾¹' °t¦X¨}¦n¡D¦¨¥\ªº®×¨Ò¦³¨Ï¥Î Unix, Windows95, Windows NT, Windows for Workgroup (with TCP/IP package), OS/2, Macintosh System's OS with Mac TCP, Mac Open Transport, DOS with NCSA Telnet package, VAX, Alpha with Linux, ¬Æ¦Ü Amiga with AmiTCP ©Î AS225-stack ªº¨t²Î¡D

2.3. ½Ö¥i¥H±q IP Masquerade ¤¤Àò¯q?

2.4. ½Ö¤£»Ý­n IP Masquerade?

2.5. IP Masquerade ¬O¦p¦ó¹B§@ªº?

¸`¦Û Ken eves ªº IP Masquerade FAQ:

  ³o¬O¤j³¡¤À²³æªº³]©w¯ó¹Ï:

     SLIP/PPP         +------------+                         +-------------+
     to provider      |  Linux     |       SLIP/PPP          | Anybox      |
    <---------- modem1|            |modem2 ----------- modem |             |
      111.222.333.444 |            |           192.168.1.100 |             |
                      +------------+                         +-------------+

          ¤W­±ªº¯ó¹Ï¤¤¤@¥x¦w¸Ë¨Ã°õ¦æ ip_masquerading  ªº Linux
      ¾÷¾¹¨Ï¥Î modem1 ¸g¥Ñ SLIP/or/PPP  ³s±µºô»Úºô¸ô¡D¥¦¦³¤@­Ó
      «ü©wªº IP ¦ì§} 111.222.333.444¡D¥¦³]©w modem2 ¤¹³\¼·±µªÌ
      ñ¤J¨Ã°_©l SLIP/or/PPP  ³sµ²¡D

          ²Ä¤G­Ó¨t²Î¡]¤£¥²¬O°õ¦æ Linux  ªº¨t²Î¡^¼·±µ¶i¤J Linux
      ¾÷¾¹¨Ã°_©l SLIP/or/PPP  ³sµ²¡D¥¦¦bºô»Úºô¸ô¤W¨Ã¨S¦³«ü©wªº
      IP  ¦ì§}©Ò¥H¥¦¨Ï¥Î 192.168.1.100¡D¡]°Ñ¾\¤U­z¡^

          °t¦X ip_masquerade  ¤Î¾A·í»¼°e°t¸m(routing configured)
      Anybox  ³o¥x¾÷¾¹¥i¥H¸òºô»Úºô¸ô¥æ¬y´N¦p¦P¥¦¯uªº³s¦b¤W­±¯ë
      ¡]°£¤F¤Ö¼Æ¨Ò¥~¡^¡D

  ¸`¿ý Pauline Middelink:
      §O§Ñ°O´£¨ì ANYBOX À³¸Ó§â Linux  ¾÷¾¹·í§@¥¦ªº¹h¹D¡]µL½×¬O
      ¹w³]»¼°e¸ô®|©Î¥u¬O­Ó¤lºô¸ô³£¨SÃö«Y¡^¡D¦pªG ANYBOX ¤£¯à°÷
      ³o¼Ë³]¡A Linux  ¾÷¾¹À³¸Ó¬°©Ò¦³­n»¼°eªº¦ì§}°µ¥N²z¦ì§}¸ÑªR
      ªR¨ó©w(proxy arp) ªA°È¡A¦ý¥N²z¦ì§}¸ÑªRªº³]©w¶W¹L³o¥÷¤å¥ó
      ªº½d³ò¡D

  ¤U­±¸`¿ý¦Û comp.os.linux.networking ªº¤@½g¥¬§i¨Ã¥Bµy¥[½s¿è¥H
  ²Å¦X¤W­z½d¨Òªº¥Îµü:

  ¡C§Ú§i¶D ANYBOX ³o¥x¾÷¾¹¶] slip ªº linux  ¾÷¾¹¬O¥¦ªº¹h¹D¡D
  ¡C·í¤@­Ó«Ê¥]±q ANYBOX ¶i¤J linux  ¾÷¾¹®É¡A¥¦·|«ü©w·sªº¨Ó·½°ð
    ¸¹(source port number)¡A§â¥¦¦Û¤vªº ip ¦ì§}¶ë¤J«Ê¥]ªº¼ÐÀY¨Ã
    Àx¦s­ì¨Óªº¡DµM«á¥¦±N·|ÂÇ¥Ñ SLIP/or/PPP  ¬É­±§â­×§ï¹Lªº«Ê¥]
    °e¤Wºô»Úºô¸ô¡D
  ¡C·í¤@­Ó«Ê¥]±qºô»Úºô¸ô¨Ó¨ì linux  ¾÷¾¹®É¡A¦pªG°ð¸¹¬O¤W­±«ü©w
    ªº¨ä¤¤¤@­Ó¡A¥¦±N·|¨ú¥X­ì¨Óªº°ð¸¹¥H¤Î ip ¦ì§}¡A§â¥¦­Ì©ñ¦^«Ê
    ¥]ªº¼ÐÀY¡A¨Ã¥B§â«Ê¥]°e©¹ ANYBOX ¡D
  ¡C°e¥X«Ê¥]ªº¥D¾÷±N¥Ã»·¤£ª¾¹D¨ä¤¤ªº®t§O¡D

¤@­Ó IP Masquerading ªº¨Ò¤l:

¤U­±ªº¹Ï¥Ü¬O¨å«¬ªº¨Ò¤l:-


    +----------+
    |          |  Ethernet
    | abox     |::::::
    |          |2    :192.168.1.x
    +----------+     :
                     :   +----------+   PPP   
    +----------+     :  1|  Linux   |   link
    |          |     ::::| masq-gate|:::::::::// Internet
    | bbox     |::::::   |          |
    |          |3    :   +----------+
    +----------+     :
                     :
    +----------+     :
    |          |     :
    | cbox     |::::::
    |          |4    
    +----------+  
                

    <-Internal Network->
¦b³o­Ó¨Ò¤l¤¤§Ú­Ì¦Ò¼{¥|¥x¹q¸£¨t²Î¡]·Q¥²»»»·ªº¥k¤èÁÙ¦³¨ÇªF¦èÅý§A¨ìºô»Úºô¸ôªº IP ³s½u¯à°÷³s±µ¡A¥H¤Î¤@¨Ç¡]»·¶W¹L³o¤@­¶¡^¦bºô»Úºô¸ô¤W§A¦³¿³½ì¥æ´«¸ê°TªºªF¦è¡^¡D ³o­Ó Linux ¨t²Î masq-gate ¬O abox, bbox, cbox ¤º³¡ºô¸ô¾÷¾¹³s±µºô»Úºô¸ôªº°°¸Ë¹h¹D¡D ¤º³¡ºô¸ô¨Ï¥Î«ü©wªº¨p¥Î(private) ºô¸ô¦ì§}¡A¦b³o­Ó®×¨Ò¤¤¬O class C ºô¸ô 192.168.1.0, Linux ¾÷¾¹¾Ö¦³¦ì§} 192.168.1.1 ¦Ó¨ä¥¦¨t²Î¤]¾Ö¦³¦¹ºô¸ô¤Wªº¦ì§}¡D

³o¤T¥x¾÷¾¹ abox, bbox ¥H¤Î cbox (¥¦­Ì¥i¥H°õ¦æ¥ô¦ó§@·~¨t²Î ¡Ð ¹³¬O Windows 95, Macintosh MacTCP ©Î¬Æ¦Ü¬O¥t¤@¥x Linux ¾÷¾¹¡A¥u­n¥¦­Ì¯à¤F¸Ñ IP)¥i¥H³s½u¨ìºô»Úºô¸ô¤Wªº¨ä¥¦¾÷¾¹¥h¡AµM¦Ó³o­Ó°°¸Ë¨t²Î¹h¹D masq-gate Âà´«¥¦­Ì©Ò¦³ªº³s½u©Ò¥H³o¨Ç³s½u¬Ý°_¨Ó¹³¬O­ì¥»§Y±q°°¸Ë¹h¹D masq-gate ¥»¨­µo¥Xªº¡A¦Ó¥BÁÙ¦w±Æ°°¸Ë³s½u¶Ç¦^ªº¸ê®ÆÂà¦^­ì¥ýªº¨t²Î ¡Ð ©Ò¥H¦b¤º³¡ºô¸ô¤Wªº¨t²Î¬Ý¨ìªº¬Oª½±µ³q©¹ºô»Úºô¸ôªº»¼°e¸ô®|¦Ó¥B¤£ª¾¹D¥L­Ìªº¸ê®Æ³Q°°¸Ë¹L¡D

2.6. ¦b Linux 2.x ¤W¨Ï¥Î IP Masquerade ªº»Ý¨D

** ½Ð°Ñ¦Ò IP Masquerade Resource ¥HÀò±o³Ì·s¸ê°T¡A¦]¬°¸g±`§ó·s³o¥÷ HOWTO ¬Oº¡§xÃøªº¡D **


Linux IP Masquerade mini HOWTO ¤¤Ä¶ª© : ­I´ºª¾ÃÑ
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