1. NATïŒãããã¯ãŒã¯ã¢ãã¬ã¹å€æïŒã®æŠèŠ
NATïŒãããã¯ãŒã¯ã¢ãã¬ã¹å€æïŒã¯ãã€ã³ã¿ãŒãããæ¥ç¶ãå¯èœã«ãããã³ã³ãã¥ãŒã¿ãããã¯ãŒã¯ã®éèŠãªèŠçŽ ã§ãããã®æè¡ã¯ãäžèŠè€éã«èŠãããããããŸããããæ¬è³ªçã«ã¯éåžžã«ã·ã³ãã«ã§çŽæçã§ããæ¬èšäºã§ã¯ãNATã®åºæ¬çãªæŠå¿µãåäœã«ã€ããŠè©³ãã解説ããã©ã®ããã«ããŠã€ã³ã¿ãŒããããçŸåšã®åœ¢ã«ãªã£ãã®ããç解ããæå©ããããŸãã
1.1 NATã®å¿ èŠæ§ãšç®ç
NATã¯ãäžé£ã®ã«ãŒã«ã䜿çšããŠããããã¯ãŒã¯äžã®ã³ã³ãã¥ãŒã¿ãŒéã§æ å ±ãéåä¿¡ãããæ¹æ³ãå¶åŸ¡ããŸãããã®äž»ãªç®çã¯ãIPã¢ãã¬ã¹ã®æå¹ãªäœ¿çšãä¿é²ããåæã«ãã©ã€ãã·ãŒãšã»ãã¥ãªãã£ã匷åããããšã§ãã
äžã€ã®ãããã¯ãŒã¯å ã«ããè€æ°ã®ããã€ã¹ãåæã«ã€ã³ã¿ãŒãããæ¥ç¶ãè¡ãå Žåãããããã®ããã€ã¹ã«åºæã®ãããªãã¯IPã¢ãã¬ã¹ãå²ãåœãŠãããšã¯å¹ççã§ã¯ãããŸãããããã ãã§ãªããIPã¢ãã¬ã¹ã¯æéã®ãªãœãŒã¹ã§ãããå šäžçã§äœ¿çšå¯èœãªIPv4ã¢ãã¬ã¹ã¯çŽ43ååãããããŸããããã®æ°ã¯äººé¡ã䜿çšããããã€ã¹ã®æ°ãã¯ããã«äžåã£ãŠããŸãããããNATãååšããæãéèŠãªçç±ã§ãã
ãŸããNATã¯ããã€ã¹ã®èå¥æ å ±ãå€éšããèŠããªãããããšã§ããããã¯ãŒã¯ã»ãã¥ãªãã£ãåäžãããŸããå éšãããã¯ãŒã¯ã®IPã¢ãã¬ã¹ãçŽæ¥å€éšã«é²åºããªããããå€éšã®æ»æè ãç¹å®ã®ããã€ã¹ãã¿ãŒã²ããã«ããããšãå°é£ã«ãªããŸãã
1.2 NATã®åºæ¬çãªä»çµã¿
NATã®ä»çµã¿ã¯ããããã¯ãŒã¯äžã®ããã€ã¹ïŒãã©ã€ããŒããããã¯ãŒã¯ïŒãšã€ã³ã¿ãŒãããïŒãããªãã¯ãããã¯ãŒã¯ïŒãšã®éã§ãIPã¢ãã¬ã¹ãå€æããããšã«åºã¥ããŠããŸãã
ããã€ã¹ãã€ã³ã¿ãŒãããäžã®ãªãœãŒã¹ã«ã¢ã¯ã»ã¹ããããšãããšããã®ãªã¯ãšã¹ãã¯ãŸãNATã«ãŒã¿ã«éãããŸããNATã«ãŒã¿ã¯ããã€ã¹ã®ãã©ã€ããŒãIPã¢ãã¬ã¹ããããªãã¯IPã¢ãã¬ã¹ã«å€æãããã®å€æãèšé²ããŸãããããŠãå€æåŸã®IPã¢ãã¬ã¹ã䜿ã£ãŠãªã¯ãšã¹ããã€ã³ã¿ãŒãããã«éããŸãã
ã€ã³ã¿ãŒãããäžã®ãªãœãŒã¹ããã®ã¬ã¹ãã³ã¹ãNATã«ãŒã¿ã«å°çãããšãã«ãŒã¿ã¯èªèº«ãèšé²ããå€ææ å ±ãå ã«ããããªãã¯IPã¢ãã¬ã¹ãå ã®ãã©ã€ããŒãIPã¢ãã¬ã¹ã«æ»ããŸãããããŠããã®ã¬ã¹ãã³ã¹ãæ£ããããã€ã¹ã«éä¿¡ããŸããããã«ãããè€æ°ã®ããã€ã¹ãåããããªãã¯IPã¢ãã¬ã¹ãå ±æããªããããããããç¬ç«ããã€ã³ã¿ãŒãããæ¥ç¶ãä¿ã€ããšãã§ããŸãã
ããã€ã¹ | ãã©ã€ããŒãIPã¢ãã¬ã¹ | ãããªãã¯IPã¢ãã¬ã¹ |
---|---|---|
ããã€ã¹1 | 192.168.1.2 | 203.0.113.0 |
ããã€ã¹2 | 192.168.1.3 | |
ããã€ã¹3 | 192.168.1.4 |
ãã®è¡šã¯NATã®åºæ¬çãªæ©èœã瀺ããŠããŸãã3ã€ã®ããã€ã¹ãåããããªãã¯IPã¢ãã¬ã¹ãå ±æããªããããããããç°ãªããã©ã€ããŒãIPã¢ãã¬ã¹ãæã€ããšãã§ããŸãã
2. NATã®çš®é¡ãšãã®ç¹åŸŽ
NATã«ã¯äž»ã«äžã€ã®ç°ãªã圢åŒãååšããŸãïŒéçNATïŒStatic NATïŒãåçNATïŒDynamic NATïŒããããŠããŒãã¢ãã¬ã¹å€æïŒPATïŒããããã®å圢åŒã¯ç¹å®ã®ç¶æ³ãèŠä»¶ã«å¯Ÿå¿ããããã«èšèšãããŠãããããããããããã¯ãŒã¯æ¥ç¶ã«ç¬ç¹ã®å©ç¹ãæäŸããŸãã
2.1 éçNAT (Static NAT)
éçNATã¯ããã©ã€ããŒãIPã¢ãã¬ã¹ãšãããªãã¯IPã¢ãã¬ã¹ã®éã®äžå¯Ÿäžã®é¢ä¿ãäœããŸãããã®åœ¢åŒã§ã¯ãã«ãŒã¿ããã©ã€ããŒãIPã¢ãã¬ã¹ãšãããªãã¯IPã¢ãã¬ã¹ã®ãã¢ãèšæ¶ãããã®ãã¢ãåžžã«äžç·ã«äœ¿çšããŸãããã®æ¹åŒã¯ãç¹å®ã®ããã€ã¹ãåžžã«åããããªãã¯IPã¢ãã¬ã¹ãæã€ããšãå¿ èŠãšããç¶æ³ãäŸãã°ããµãŒããŒãå€éšããçŽæ¥ã¢ã¯ã»ã¹å¯èœã§ããã¹ãå Žåãªã©ã«åœ¹ç«ã¡ãŸãã
2.2 åçNAT (Dynamic NAT)
åçNATã¯ããã©ã€ããŒãIPã¢ãã¬ã¹ãšãããªãã¯IPã¢ãã¬ã¹ã®éã®é¢ä¿ãåçã«äœããŸããããã¯äžå¯Ÿäžã®ãããã³ã°ã§ãããç¹å®ã®ãã©ã€ããŒãIPã¢ãã¬ã¹ãåžžã«åããããªãã¯IPã¢ãã¬ã¹ã«ãããã³ã°ãããããã§ã¯ãããŸããã代ããã«ãå©çšå¯èœãªãããªãã¯IPã¢ãã¬ã¹ã®ããŒã«ããå¿ èŠã«å¿ããŠã¢ãã¬ã¹ãå²ãåœãŠãããŸããããã¯ã倧éã®ããã€ã¹ãåæã«ã€ã³ã¿ãŒãããæ¥ç¶ãå¿ èŠãšããã倧èŠæš¡ãªãããã¯ãŒã¯ç°å¢ã§æçšã§ãã
2.3 ããŒãã¢ãã¬ã¹å€æ (PAT)
ããŒãã¢ãã¬ã¹å€æïŒPATïŒãå¥åNATãªãŒããŒããŒããšã¯ãè€æ°ã®ãã©ã€ããŒãIPã¢ãã¬ã¹ãåäžã®ãããªãã¯IPã¢ãã¬ã¹ã«ãããã³ã°ããæ¹åŒã§ããPATã¯IPã¢ãã¬ã¹ã ãã§ãªããéä¿¡ã®ããã®ããŒãçªå·ã䜿çšããŸãããã®æ¹åŒã§ã¯ãåããããªãã¯IPã¢ãã¬ã¹ã䜿çšããªããããç°ãªãããã€ã¹éã®éä¿¡ãåºå¥ããããšãå¯èœã§ãããã®æè¡ã¯ãéãããæ°ã®ãããªãã¯IPã¢ãã¬ã¹ãæã€ãããã¯ãŒã¯ã§ãå€æ°ã®ããã€ã¹ãã€ã³ã¿ãŒãããã«æ¥ç¶ããå¿ èŠãããå Žåã«ç¹ã«åœ¹ç«ã¡ãŸãã
NATã®çš®é¡ | ç¹åŸŽ | é©çšç¶æ³ |
---|---|---|
éçNAT | äžå¯Ÿäžã®IPã¢ãã¬ã¹ã®ãããã³ã°ãåžžã«åããããªãã¯IPã¢ãã¬ã¹ã䜿çšã | ç¹å®ã®ããã€ã¹ïŒäŸãã°ãµãŒããŒïŒãå€éšããçŽæ¥ã¢ã¯ã»ã¹å¯èœã§ããã¹ãå Žåã |
åçNAT | äžå¯Ÿäžã®IPã¢ãã¬ã¹ã®ãããã³ã°ãå©çšå¯èœãªãããªãã¯IPã¢ãã¬ã¹ããåçã«å²ãåœãŠã | 倧éã®ããã€ã¹ãåæã«ã€ã³ã¿ãŒãããæ¥ç¶ãå¿ èŠãšããã倧èŠæš¡ãªãããã¯ãŒã¯ç°å¢ã |
ããŒãã¢ãã¬ã¹å€æïŒPATïŒ | å€å¯Ÿäžã®IPã¢ãã¬ã¹ã®ãããã³ã°ãIPã¢ãã¬ã¹ãšããŒãçªå·ã䜿çšã | éãããæ°ã®ãããªãã¯IPã¢ãã¬ã¹ãæã€ãããã¯ãŒã¯ã§ãå€æ°ã®ããã€ã¹ãã€ã³ã¿ãŒãããã«æ¥ç¶ããå¿ èŠãããå Žåã |
ãã®è¡šã¯ãåçš®NATã®åºæ¬çãªç¹åŸŽãšãã®é©çšç¶æ³ããŸãšããŠããŸããããããã®NAT圢åŒã¯ãç¹å®ã®ãããã¯ãŒã¯èŠä»¶ãç¶æ³ã«å¯Ÿå¿ããããã«äœ¿çšãããŸãã
3. NATã®å ·äœçãªé©çšäŸ
ãããŸã§ã§NATã®åºæ¬çãªæŠå¿µãšçš®é¡ãèŠãŠããŸããããããããå ·äœçã«ã©ã®ããã«äœ¿ãããŠãããã«ã€ããŠèå¯ããŸããããã§ã¯ãããŒã ãããã¯ãŒã¯ãšäŒæ¥ãããã¯ãŒã¯ã®äºã€ã®äžè¬çãªç°å¢ã§ã®NATã®é©çšäŸãåãäžããŸãã
3.1 ããŒã ãããã¯ãŒã¯ã«ãããNAT
家åºã®ãããã¯ãŒã¯ç°å¢ã§æãäžè¬çã«äœ¿çšãããNATã®åœ¢åŒã¯ããŒãã¢ãã¬ã¹å€æïŒPATïŒã§ããå€ãã®å®¶åºã§ã¯ãäžã€ã®ãããªãã¯IPã¢ãã¬ã¹ã䜿çšããŠãè€æ°ã®ããã€ã¹ïŒã¹ããŒããã©ã³ãããœã³ã³ãã²ãŒã æ©ãªã©ïŒãã€ã³ã¿ãŒãããã«æ¥ç¶ããŸãã家åºã®Wi-Fiã«ãŒã¿ã¯éåžžããã®PATã®åœ¹å²ãæãããŠããã家åºå ã®åããã€ã¹ãã€ã³ã¿ãŒããããšéä¿¡ã§ããããã«ããŸãã
3.2 äŒæ¥ãããã¯ãŒã¯ã«ãããNAT
äžæ¹ãäŒæ¥ã®ãããã¯ãŒã¯ç°å¢ã§ã¯ãéçNATãåçNATããããŠPATã®åçš®NATãé©åã«å©çšãããŸããäŸãã°ãäŒæ¥ãå éšãµãŒãïŒã¡ãŒã«ãµãŒãããŠã§ããµãŒããªã©ïŒãéçšããŠããããããå€éšããçŽæ¥ã¢ã¯ã»ã¹å¯èœã§ããã¹ãå ŽåãéçNATã䜿çšãããŸãããã®éçNATã«ããããµãŒãã¯åžžã«åããããªãã¯IPã¢ãã¬ã¹ãæã€ããšã«ãªããã€ã³ã¿ãŒãããäžããäžè²«ããŠã¢ã¯ã»ã¹å¯èœãšãªããŸãã
äžæ¹ãäžè¬ã®ç€Ÿå¡ãæ¥åçšããã€ã¹ããã€ã³ã¿ãŒãããã«æ¥ç¶ããå¿ èŠãããå ŽåãåçNATãPATã䜿çšãããŸãããããã®æ¹åŒã«ãããäŒæ¥ã¯æéãªæ°ã®ãããªãã¯IPã¢ãã¬ã¹ãå¹ççã«äœ¿çšããªãããå€æ°ã®ããã€ã¹ãã€ã³ã¿ãŒãããã«æ¥ç¶ã§ããããã«ããŸãã
ãã®ããã«ãNATã¯ãããã¯ãŒã¯ç°å¢ã®ããŒãºãèŠä»¶ã«å¿ããŠãæ§ã ãªåœ¢ã§é©çšãããŸãã
4. NATãšIPã¢ãã¬ã¹
NATãã€ã³ã¿ãŒãããæ¥ç¶ã«éèŠãªåœ¹å²ãæããçç±ã®äžã€ã¯ããããIPã¢ãã¬ã¹ãšå¯æ¥ã«é¢é£ããŠããããã§ãããã®ã»ã¯ã·ã§ã³ã§ã¯ãIPã¢ãã¬ã¹ã®çš®é¡ãšåœ¹å²ãIPv4ã¢ãã¬ã¹ã®æ¯æžåé¡ããããŠIPv6ãšNATã®é¢ä¿ã«ã€ããŠæãäžããŠãããŸãã
4.1 IPã¢ãã¬ã¹ã®çš®é¡ãšåœ¹å²
IPã¢ãã¬ã¹ã¯ã€ã³ã¿ãŒãããäžã®ããã€ã¹ãäžæã«èå¥ããããã®æ°åã®çµã¿åããã§ããäž»ã«äºã€ã®çš®é¡ãIPv4ãšIPv6ããããŸããIPv4ã¯32ãããã®ã¢ãã¬ã¹ã§ã4ã€ã®1ãã€ãã®æ°å€ãããªãªãã§åºåãããŠè¡šçŸãããŸããäžæ¹ãIPv6ã¯128ãããã®ã¢ãã¬ã¹ã§ã8ã€ã®4æåã®16é²æ°ãã³ãã³ã§åºåãããŠè¡šçŸãããŸãã
IPã¢ãã¬ã¹ã¯å€§ããããããªãã¯ã¢ãã¬ã¹ããšããã©ã€ããŒãã¢ãã¬ã¹ãã«åããããŸãããããªãã¯ã¢ãã¬ã¹ã¯ã€ã³ã¿ãŒãããäžã§äžæã§ãããå€éšã®ããã€ã¹ããçŽæ¥ã¢ã¯ã»ã¹å¯èœãªã¢ãã¬ã¹ã§ããäžæ¹ããã©ã€ããŒãã¢ãã¬ã¹ã¯ããŒã«ã«ãããã¯ãŒã¯å ã§ã®ã¿æå¹ãªã¢ãã¬ã¹ã§ãå€éšããã¯çŽæ¥ã¢ã¯ã»ã¹ããããšãã§ããŸãããNATã®äž»ãªåœ¹å²ã®äžã€ã¯ããã®ãã©ã€ããŒãã¢ãã¬ã¹ãšãããªãã¯ã¢ãã¬ã¹ãšã®éã§éä¿¡ãå¯èœã«ããããšã§ãã
4.2 NATãšIPv4ã®æ¯æžåé¡
IPv4ã¢ãã¬ã¹ã¯çè«äžçŽ43åã®äžæã®ã¢ãã¬ã¹ãæäŸã§ããŸãããã€ã³ã¿ãŒãããã®æ¥éãªçºå±ãšãšãã«ããããã®ã¢ãã¬ã¹ãæ¯æžãå§ããŠããŸããNATã¯ãã®IPv4ã¢ãã¬ã¹æ¯æžåé¡ã®ç·©åçãšããŠéèŠãªåœ¹å²ãæãããŠããŸãããNATã¯ãã©ã€ããŒãIPã¢ãã¬ã¹ã䜿çšããããšã§ãäžã€ã®ãããªãã¯IPã¢ãã¬ã¹ã§è€æ°ã®ããã€ã¹ãã€ã³ã¿ãŒãããã«æ¥ç¶ã§ããããã«ããŸããããã«ãããéãããIPv4ã¢ãã¬ã¹ã®å¹ççãªå©çšãå¯èœãšãªã£ãŠããŸãã
4.3 NATãšIPv6ã®é¢ä¿
IPv6ã¯IPv4ã¢ãã¬ã¹ã®æ¯æžåé¡ã解決ããããã«éçºãããŸãããIPv6ã¯128ãããã®é·ããæã€ãããã»ãŒç¡éãšããããæ°ã®äžæã®ã¢ãã¬ã¹ãæäŸããããšãå¯èœã§ãããã®ãããçè«çã«ã¯NATã®ãããªæè¡ã¯å¿ èŠãªããªããŸãã
ããããçŸå®çã«ã¯IPv4ãšIPv6ã®æ··åšç°å¢ãç¶ããšäºæ³ããããã®éãNATã¯åŒãç¶ãéèŠãªåœ¹å²ãæããã§ãããããŸããNATãæäŸããäžéšã®ã»ãã¥ãªãã£æ©èœããã©ã€ãã·ãŒä¿è·ã®èŠ³ç¹ããããNATã®å©çšãç¶ãå¯èœæ§ããããŸãã
5. NATã®èšå®æ¹æ³ãšãã®ãã€ã³ã
ãããŸã§ã«NATã®åºæ¬æŠå¿µããã®éèŠæ§ãçš®é¡ãšç¹æ§ããããŠIPã¢ãã¬ã¹ãšã®é¢é£æ§ã«ã€ããŠèª¬æããŠããŸãããä»åºŠã¯ãå ·äœçã«NATãã©ã®ããã«èšå®ããã®ãããããŠèšå®ããéã®éèŠãªãã€ã³ãã«ã€ããŠè©³ããèŠãŠãããŸãããã
5.1 ã«ãŒã¿ãŒã«ãããNATèšå®ã®åºæ¬æé
äžè¬çãªããŒã ã«ãŒã¿ãŒãäŒæ¥åãã®ã«ãŒã¿ãŒã§ã¯ãåºæ¬çã«NATæ©èœãããªã€ã³ã¹ããŒã«ãããŠãããéåžžã¯ç¹å¥ãªèšå®ãè¡ãå¿ èŠã¯ãããŸãããããããå ·äœçãªæé ãç¥ã£ãŠããããšã§ãèªåã®ãããã¯ãŒã¯ç°å¢ãããæ·±ãç解ããå¿ èŠãªå Žåã«ã¯èªåã§èšå®ãè¡ãããšãå¯èœãšãªããŸãã
èšå®æ¹æ³ã¯ã«ãŒã¿ãŒã®ã¡ãŒã«ãŒãã¢ãã«ã«ããç°ãªããŸãããäžè¬çãªæé ã¯æ¬¡ã®ãšããã§ãïŒ
1. ã«ãŒã¿ãŒã®ç®¡çç»é¢ã«ã¢ã¯ã»ã¹ããŸããéåžžã¯ããã©ãŠã¶ã®ã¢ãã¬ã¹ããŒã«ã«ãŒã¿ãŒã®IPã¢ãã¬ã¹ãå
¥åããEnterããŒãæŒãããšã§ã¢ã¯ã»ã¹ã§ããŸãã
2. 管çç»é¢ã®ã¡ãã¥ãŒããNATãŸãã¯ãã¡ã€ã¢ãŠã©ãŒã«èšå®ã®ããŒãžãæ¢ããŸãã
3. å¿
èŠã«å¿ããŠãéçNATãåçNATããŸãã¯PATã®èšå®ãè¡ããŸãã
4. å€æŽãä¿åããŸãã
5.2 NATèšå®æã®æ³šæç¹
NATèšå®æã«ã¯ãããã€ãã®éèŠãªç¹ã«æ³šæããå¿ èŠããããŸãããŸãäžã€ç®ã¯ãã»ãã¥ãªãã£ã§ããNATèªäœã¯äžå®ã®ã»ãã¥ãªãã£æ©èœãæäŸããŸãããå šãŠã®è åšããä¿è·ããããã§ã¯ãããŸããããããã£ãŠããã¡ã€ã¢ãŠã©ãŒã«ãã¢ã³ããŠã€ã«ã¹ãœãããŠã§ã¢ãªã©ã®è¿œå ã®ã»ãã¥ãªãã£å¯Ÿçãšçµã¿åãããŠäœ¿çšããããšãæšå¥šãããŸãã
ãŸããç¹å®ã®ã¢ããªã±ãŒã·ã§ã³ãã²ãŒã ã䜿çšããéã«ã¯ãããããå¿ èŠãšããç¹å®ã®ããŒããéæŸããèšå®ãå¿ èŠã«ãªãããšããããŸãããã®ãããªå Žåã¯ãããŒããã©ã¯ãŒãã£ã³ã°ãšããæè¡ãçšããŠãç¹å®ã®ããŒããå€éšããã®éä¿¡ã«éæŸããŸãããã ããããŒããéæŸããããšã¯ã»ãã¥ãªãã£ãªã¹ã¯ãå¢å€§ãããå¯èœæ§ããããããå¿ èŠæå°éã®ããŒãã®ã¿ãéæŸãã䜿çšåŸã¯éããããã«ããããšãéèŠã§ãã
æåŸã«ãNATèšå®ãè¡ã£ãåŸã¯ãèšå®ãæ£ããæ©èœããŠããã確èªããããšãå¿ããªãããã«ããŸããããã€ã³ã¿ãŒããããžã®æ¥ç¶ç¶æ³ãç¹å®ã®ã¢ããªã±ãŒã·ã§ã³ã®åäœãªã©ã確èªããããšã§ãèšå®ãé©åã«è¡ããããããã§ãã¯ããããšãã§ããŸãã
6. NATã®å©ç¹ãšéç
NATã«ã¯å€ãã®å©ç¹ããããŸãããäžæ¹ã§éçãåé¡ç¹ãååšããŸããããããã«ã€ããŠè©³ããèŠãŠãããŸãããã
6.1 NATã®ã¡ãªãã
NATã®æ倧ã®ã¡ãªããã¯ããã©ã€ããŒãIPã¢ãã¬ã¹ã®äœ¿çšã«ããå ¬éIPã¢ãã¬ã¹ã®æ¶è²»ãæå¶ã§ããããšã§ããããã«ãããIPv4ã¢ãã¬ã¹ã®æ¯æžåé¡ãç·©åãããããã¯ãŒã¯ã€ã³ãã©ã®æ¡å€§ãæ¯ããŠããŸããã
ãŸããNATã¯ããçšåºŠã®ã»ãã¥ãªãã£ãæäŸããŸããå éšãããã¯ãŒã¯ã®IPã¢ãã¬ã¹ãå€éšã«å ¬éããã«éä¿¡ãè¡ãããããå€éšããã®äžæ£ã¢ã¯ã»ã¹ãé²ãå¹æããããŸãã
ããã«ãNATã¯ãããã¯ãŒã¯ã®åèšèšãè¡ãããšãªããIPã¢ãã¬ã¹ãå€æŽããããšãå¯èœã§ããããã«ãããäŒæ¥ã®ãããã¯ãŒã¯æ¡å€§ãåç·šæã«æè»ã«å¯Ÿå¿ããããšãã§ããŸãã
6.2 NATã®ãã¡ãªãããšåé¡ç¹
NATã«ã¯å€ãã®ã¡ãªããããããŸããããã¡ãªãããåé¡ç¹ãååšããŸããäžã€ç®ã¯ãäžéšã®ã¢ããªã±ãŒã·ã§ã³ãšã®äºææ§ã§ããNATã¯IPã¢ãã¬ã¹ãå€æãããšããæ§è³ªäžãIPã¢ãã¬ã¹ã«äŸåããéä¿¡ãè¡ãã¢ããªã±ãŒã·ã§ã³ããããã³ã«ãšã¯äžæŽåãèµ·ããããšããããŸãã
ãŸããNATã¯éä¿¡ã®ãšã³ãããŒãšã³ãååãç Žããããã€ã³ã¿ãŒãããã®åºæ¬çãªèšèšååãšã¯ç°ãªãåããããŸããããã«ããããããã¯ãŒã¯ã®ãã©ãã«ã·ã¥ãŒãã£ã³ã°ãè€éã«ãªãå ŽåããããŸãã
ããã«ãNATã¯IPã¢ãã¬ã¹ã®æ¯æžåé¡ãç·©åããäžæ¹ã§ããããæªåãããèŠå ãšããªã£ãŠããŸããNATã®ååšã«ãããIPv6ãžã®ç§»è¡ãé ããIPv4ã¢ãã¬ã¹ã®éèŠãé«ãŸã£ãŠããŸãã
7. ãŸãšãïŒNATã®ç解ãšæŽ»çšæ³ã®å確èª
æ¬èšäºã§ã¯ããããã¯ãŒã¯ã¢ãã¬ã¹å€æïŒNATïŒã®æŠèŠãããã®çš®é¡ãé©çšäŸãIPã¢ãã¬ã¹ãšã®é¢é£ãèšå®æ¹æ³ãå©ç¹ãšéçã«ã€ããŠèª¬æããŸãããNATã¯ãçŸä»£ã®ã€ã³ã¿ãŒãããéä¿¡ã«ãããŠæ¬ ããããšã®ã§ããªãæè¡ã§ããããã®ç解ãšé©åãªå©çšã¯ãããã¯ãŒã¯ç®¡çã®åºæ¬ãšèšããã§ãããã
äžæ¹ã§ãNATã®å©çšã¯ã»ãã¥ãªãã£ãéä¿¡ã®å¶çŽã䌎ããŸãããããã®åé¡ãç解ããé©åãªèšå®ãšç®¡çãè¡ãããšã§ãNATãæ倧éã«æŽ»çšããŸãããããããŠãåžžã«æ°ããæè¡ååãç¹ã«IPv6ã®æ®åç¶æ³ã«ç®ãåããé©åãªææã«ç§»è¡ããæºåãããŠããããšãéèŠã§ãã
ããããããããã¯ãŒã¯æè¡ã®çºå±ãšãšãã«ãNATã®ç解ãšæŽ»çšæ³ãæ·±ããŠãããŸãããã