1. ã¯ããã«
1.1 DHCPãšã¯ïŒ
DHCPãšã¯ãDynamic Host Configuration Protocolã®ç¥ã§ããããã¯ãŒã¯æ¥ç¶ã容æã«ããããã®æè¡ã®äžã€ã§ããå ·äœçã«ã¯ãã³ã³ãã¥ãŒã¿ãŒããããã¯ãŒã¯ã«æ¥ç¶ããéã«èªåçã«IPã¢ãã¬ã¹ãå²ãåœãŠã圹å²ãæãããŸããIPã¢ãã¬ã¹ã¯ã€ã³ã¿ãŒãããäžã®äœæã®ãããªãã®ã§ãããããã®ããã€ã¹ãäžæã«èå¥ããŸãã
äžè¬çã«ãIPã¢ãã¬ã¹ã¯æåã§èšå®ããããšãå¯èœã§ããã倧èŠæš¡ãªãããã¯ãŒã¯ã§ã¯ãã®äœæ¥ã¯è€éã§æéãããããŸããããããDHCPã䜿çšãããšãèªåçã«IPã¢ãã¬ã¹ãå²ãåœãŠãããããããããã¯ãŒã¯ç®¡çè ã®è² æ ã軜æžããããšãã§ããŸãããŸããDHCPã¯ãµãããããã¹ã¯ãããã©ã«ãã²ãŒããŠã§ã€ãDNSãµãŒããŒã®æ å ±ãªã©ããããã¯ãŒã¯æ¥ç¶ã«å¿ èŠãªä»ã®èšå®æ å ±ãèªåçã«æäŸããŸãã
1.2 æ¬èšäºã®ç®ç
ãã®èšäºã§ã¯ãDHCPã®åºæ¬çãªä»çµã¿ãç解ãããã®éèŠæ§ãšå©ç¹ãæ確ã«ããããšãç®æããŸããå ·äœçãªå©çšã·ãŒã³ãDHCPã®èšå®æ¹æ³ã«ã€ããŠã觊ããŸãããŸãããã®èšäºã¯ãããã¯ãŒã¯ã«èå³ãããæ¹ããITã®åºæ¬çãªç¥èãæ·±ããããšèããŠããæ¹åãã«æžãããŠããŸãã
æ å ±éä¿¡æè¡ã®é²åã«äŒŽããç§ãã¡ã®ç掻ã¯ãŸããŸãããžã¿ã«åããŠããŸãããã®ãããªç¶æ³äžã§ãDHCPã®ãããªãããã¯ãŒã¯ã®åºæ¬çãªæ©èœãç解ããããšã¯ãããããã®ããã€ã¹ãã©ã®ããã«ã€ã³ã¿ãŒãããã«æ¥ç¶ããæ å ±ãããåãããŠããã®ããç解ããäžã§éåžžã«åœ¹ç«ã¡ãŸãã
2. DHCPã®åºæ¬æŠå¿µ
2.1 ãããã¯ãŒã¯ãšã¯
ãããã¯ãŒã¯ãšã¯ãè€æ°ã®ã³ã³ãã¥ãŒã¿ãŒãããã€ã¹ãæ¥ç¶ãããæ å ±ããªãœãŒã¹ãå ±æã§ããããã«ããã·ã¹ãã ã®ããšãæããŸããã€ã³ã¿ãŒãããã¯ãäžçäžã®å€æ°ã®ã³ã³ãã¥ãŒã¿ãŒãšãããã¯ãŒã¯ãçžäºã«æ¥ç¶ãããæ倧ã®ãããã¯ãŒã¯ã§ãããããã¯ãŒã¯ã«ã¯ããŸããŸãªçš®é¡ããããèŠæš¡ãæ¥ç¶æ¹æ³ã«ãã£ãŠåé¡ãããŸããããšãã°ãèªå® ããªãã£ã¹ã§äœ¿çšãããå°èŠæš¡ãªãããã¯ãŒã¯ãLANïŒLocal Area NetworkïŒãšåŒã³ãåºç¯ãªå°åãã«ããŒãããããã¯ãŒã¯ãWANïŒWide Area NetworkïŒãšåŒã³ãŸãã
2.2 IPã¢ãã¬ã¹ãšã¯
IPã¢ãã¬ã¹ã¯ãã€ã³ã¿ãŒããããããã³ã«ïŒIPïŒã«ãã£ãŠåããã€ã¹ã«å²ãåœãŠãããäžæã®èå¥åã§ããããã¯ã€ã³ã¿ãŒãããäžã®ãäœæãã®ãããªãã®ã§ãåããã€ã¹ãä»ã®ããã€ã¹ãšéä¿¡ããéã«ãã¡ãã»ãŒãžãæ£ç¢ºã«éä¿¡å ã«å±ãããã«ããããã«äœ¿çšãããŸããIPã¢ãã¬ã¹ã«ã¯ãIPv4ïŒã€ã³ã¿ãŒããããããã³ã«ããŒãžã§ã³4ïŒãšIPv6ïŒã€ã³ã¿ãŒããããããã³ã«ããŒãžã§ã³6ïŒã®2ã€ã®ããŒãžã§ã³ããããŸããIPv4ã¯32ãããã®ã¢ãã¬ã¹ç©ºéãæã¡ãæ倧çŽ43åã®ã¢ãã¬ã¹ãæäŸã§ããŸããäžæ¹ãIPv6ã¯128ãããã®ã¢ãã¬ã¹ç©ºéãæã¡ãã»ãŒç¡éã®æ°ã®ã¢ãã¬ã¹ãæäŸã§ããŸãã
2.3 DHCPã®åœ¹å²
DHCPã®äž»ãªåœ¹å²ã¯ãããã€ã¹ã«èªåçã«IPã¢ãã¬ã¹ãå²ãåœãŠãããšã§ããããã€ã¹ããããã¯ãŒã¯ã«æ¥ç¶ããéãDHCPãµãŒããŒã¯å©çšå¯èœãªIPã¢ãã¬ã¹ã®ããŒã«ããäžã€ãéžãã§ããã€ã¹ã«å²ãåœãŠãããã€ã¹ãä»ã®ãããã¯ãŒã¯ããã€ã¹ãšéä¿¡ã§ããããã«ããŸãã
ãŸããDHCPã¯å²ãåœãŠãIPã¢ãã¬ã¹ãããªãŒã¹ãããŸããããã¯äžæçãªå²ãåœãŠã§ãããç¹å®ã®æéãçµéãããšæŽæ°ãŸãã¯å€æŽãããŸããããã«ãããäžèŠã«ãªã£ãIPã¢ãã¬ã¹ãåå©çšå¯èœã«ãªããIPã¢ãã¬ã¹ã®å¹ççãªäœ¿çšãå¯èœãšãªããŸãã
ããã«ãDHCPã¯IPã¢ãã¬ã¹ã ãã§ãªãããµãããããã¹ã¯ãããã©ã«ãã²ãŒããŠã§ã€ãDNSãµãŒããŒã®æ å ±ãªã©ããããã¯ãŒã¯æ¥ç¶ã«å¿ èŠãªèšå®æ å ±ãæäŸããŸããããã«ããããŠãŒã¶ãŒã¯ãããã®æ å ±ãæåã§å ¥åããå¿ èŠããªãããããã¯ãŒã¯æ¥ç¶ã®æéã軜æžã§ããŸãã
3. DHCPã®åäœããã»ã¹
3.1 DORAããã»ã¹ãšã¯
DHCPã®åäœã¯äžè¬çã«DORAããã»ã¹ãšåŒã°ããããã¯DiscoveryãOfferãRequestãAcknowledgementã®4ã€ã®ã¹ãããããæãç«ã£ãŠããŸãã
ã¹ããã | 説æ |
---|---|
Discovery | ã¯ã©ã€ã¢ã³ãïŒIPã¢ãã¬ã¹ãå¿ èŠãšããããã€ã¹ïŒããããã¯ãŒã¯ã«DHCP Discoverã¡ãã»ãŒãžããããŒããã£ã¹ãããŸããããã¯ãIPã¢ãã¬ã¹ãå¿ èŠãšããŠããŸãããšããèŠæ±ã®ãããªãã®ã§ãã |
Offer | DHCPãµãŒããŒã¯ãã®èŠæ±ãåãåããå©çšå¯èœãªIPã¢ãã¬ã¹ãéžãã§ãããã¯ã©ã€ã¢ã³ãã«OfferïŒæäŸïŒããŸãã |
Request | ã¯ã©ã€ã¢ã³ãã¯Offerãåãåãããã®IPã¢ãã¬ã¹ã䜿çšããããã®RequestïŒèŠæ±ïŒãDHCPãµãŒããŒã«éããŸãã |
Acknowledgement | DHCPãµãŒããŒã¯æçµçã«ãã®èŠæ±ãAcknowledgementïŒæ¿èªïŒããã¯ã©ã€ã¢ã³ãã«ãã®IPã¢ãã¬ã¹ã®äœ¿çšãèš±å¯ããŸãããããšåæã«ãä»ã®ãããã¯ãŒã¯æ å ±ïŒäŸãã°ããµãããããã¹ã¯ãããã©ã«ãã²ãŒããŠã§ã€ãªã©ïŒãã¯ã©ã€ã¢ã³ãã«éãããŸãã |
3.2 DHCPãµãŒããšã¯ã©ã€ã¢ã³ãã®ã³ãã¥ãã±ãŒã·ã§ã³
DHCPãµãŒããšã¯ã©ã€ã¢ã³ãã®éã®ã³ãã¥ãã±ãŒã·ã§ã³ã¯ãäžèšã®DORAããã»ã¹ã«åºã¥ããŠããŸãããã®ããã»ã¹ãéããŠããããã¯ãŒã¯äžã®æ°ããããã€ã¹ã¯èªåçã«IPã¢ãã¬ã¹ãååŸããä»ã®ããã€ã¹ãšéä¿¡ããæºåãæŽããããšãã§ããŸãã
DHCPã®ãã®èªåçãªããã»ã¹ã¯ããããã¯ãŒã¯ç®¡çè ãåããã€ã¹ã«æåã§IPã¢ãã¬ã¹ãå²ãåœãŠãæéãçããæ°ããããã€ã¹ãã¹ã ãŒãºã«ãããã¯ãŒã¯ã«æ¥ç¶ãããããšãä¿èšŒããŸãããŸãããã®ããã»ã¹ã¯éæã§ããšã³ããŠãŒã¶ãŒãä»å ¥ããããšãªãèªåçã«è¡ãããŸãã
4. DHCPã®èšå®æ¹æ³
4.1 DHCPãµãŒãã®èšå®
DHCPãµãŒãã®èšå®ã¯ãéåžžããããã¯ãŒã¯ç®¡çè ãŸãã¯ITå°é家ã«ãã£ãŠè¡ãããŸãããŸãæåã«ã管çè ã¯DHCPãµãŒããœãããŠã§ã¢ãã€ã³ã¹ããŒã«ãããã®äžã§å¿ èŠãªèšå®ãè¡ããŸããããã«ã¯ãå²ãåœãŠãIPã¢ãã¬ã¹ã®ç¯å²ïŒã¹ã³ãŒãïŒãIPã¢ãã¬ã¹ã®ãªãŒã¹æéããããã¯ãŒã¯ã®ä»ã®è©³çŽ°ïŒãµãããããã¹ã¯ãããã©ã«ãã²ãŒããŠã§ã€ãDNSãµãŒããªã©ïŒãæå®ããäœæ¥ãå«ãŸããŸãã
ãããã®èšå®ã¯äžåºŠè¡ãã°ã以éã¯DHCPãµãŒããèªåçã«IPã¢ãã¬ã¹ãããã€ã¹ã«å²ãåœãŠããªãŒã¹æéãçµéãããæŽæ°ãããšããããã»ã¹ã管çããŸãã
4.2 DHCPã¯ã©ã€ã¢ã³ãã®èšå®
ã¯ã©ã€ã¢ã³ãåŽã§ã®DHCPã®èšå®ã¯ã倧æµã®å ŽåãOSã®ãããã¯ãŒã¯èšå®ã®äžéšãšããŠè¡ãããŸããWindowsãmacOSãLinuxãªã©ã®ã»ãšãã©ã®OSã§ã¯ããããã¯ãŒã¯ã€ã³ã¿ãŒãã§ãŒã¹ã«ãŒãïŒNICïŒã®èšå®ã§ãIPã¢ãã¬ã¹ãèªåååŸããããŸãã¯ãDHCPã䜿çšããããéžæããããšã§ãDHCPã¯ã©ã€ã¢ã³ããšããŠåäœããŸãã
ãã®èšå®ãè¡ããšãããã€ã¹ããããã¯ãŒã¯ã«æ¥ç¶ããéã«ã¯èªåçã«DHCPãµãŒãã«å¯ŸããŠIPã¢ãã¬ã¹ã®ãªã¯ãšã¹ããè¡ãããµãŒãããæäŸãããIPã¢ãã¬ã¹ãšãã®ä»ã®ãããã¯ãŒã¯èšå®ã䜿çšããŸãã
éåžžããšã³ããŠãŒã¶ãŒã¯ãã®ããã»ã¹ã«ã€ããŠæ·±ãèããå¿ èŠã¯ãããŸããããªããªããã»ãšãã©ã®ããã€ã¹ã¯ããã©ã«ãã§DHCPã䜿çšããèšå®ã«ãªã£ãŠãããç¹ã«äœãããªããŠãèªåçã«é©åãªãããã¯ãŒã¯èšå®ãååŸããŸãã
5. DHCPã®å©ç¹ãšæ¬ ç¹
5.1 DHCPã®å©ç¹
DHCPã«ã¯å€ãã®å©ç¹ããããŸãããã®äžã€ã¯ãIPã¢ãã¬ã¹ã®å²ãåœãŠãèªååããããšã§ãããã¯ãŒã¯ç®¡çè ã®è² æ ã軜æžãããããã¯ãŒã¯æ¥ç¶ã®ããã»ã¹ãã¹ã ãŒãºã«è¡ãããšãã§ããŸããç¹ã«å€§èŠæš¡ãªãããã¯ãŒã¯ãé »ç¹ã«ããã€ã¹ãè¿œå ãããç°å¢ã§ã¯ãDHCPã¯è²ŽéãªããŒã«ãšãªããŸãã
ãŸããDHCPã䜿çšããããšã§ãIPã¢ãã¬ã¹ã®ç«¶åãéè€ãé²ãããšãã§ããŸããããããã®IPã¢ãã¬ã¹ã¯ãããã¯ãŒã¯å ã§ãŠããŒã¯ã§ããå¿ èŠããããŸãããæåã§ç®¡çããŠãããšèª€ã£ãŠåãIPã¢ãã¬ã¹ã2ã€ã®ããã€ã¹ã«å²ãåœãŠãŠããŸãå¯èœæ§ããããŸããããããDHCPãèªåçã«IPã¢ãã¬ã¹ãå²ãåœãŠãããšã§ããã®ãããªåé¡ãé¿ããããšãã§ããŸãã
5.2 DHCPã®æ¬ ç¹
äžæ¹ãDHCPã«ã¯ããã€ãã®æ¬ ç¹ãååšããŸããäžã€ã¯ãã»ãã¥ãªãã£äžã®åé¡ã§ããDHCPã¯åºæ¬çã«ã¯ãããã¯ãŒã¯ã«æ¥ç¶ããããšããå šãŠã®ããã€ã¹ã«IPã¢ãã¬ã¹ãæäŸããŸããããã¯äžæ£ãªããã€ã¹ããããã¯ãŒã¯ã«æ¥ç¶ããã®ã容æã«ããŠããŸãå¯èœæ§ããããŸãããã®åé¡ãé²ãããã«ã¯ãDHCPãµãŒãã®èšå®ã§ç¹å®ã®ããã€ã¹ã®MACã¢ãã¬ã¹ã®ã¿ã«IPã¢ãã¬ã¹ãæäŸãããªã©ãè¿œå ã®ã»ãã¥ãªãã£æªçœ®ãå¿ èŠãšãªããŸãã
ãŸããIPã¢ãã¬ã¹ãåçã«å€æŽãããããšã¯ãç¹å®ã®ãããã¯ãŒã¯ãµãŒãã¹ãæäŸãããµãŒããªã©ãåºå®ã®IPã¢ãã¬ã¹ãå¿ èŠãšããããã€ã¹ã«ã¯äžé©åã§ããããããããã«ã€ããŠã¯DHCPãµãŒãã®èšå®ã§ç¹å®ã®ããã€ã¹ã«ã¯åžžã«åãIPã¢ãã¬ã¹ãå²ãåœãŠããäºçŽããè¡ãããšã§å¯Ÿå¿ããããšãã§ããŸãã
6. DHCPã®æŽ»çšäºäŸ
6.1 家åºå ã®ãããã¯ãŒã¯
å€ãã®å®¶åºã§ã¯ãWi-Fiã«ãŒã¿ãDHCPãµãŒããšããŠæ©èœãã家åºå ã®åããã€ã¹ã«èªåçã«IPã¢ãã¬ã¹ãå²ãåœãŠãŠããŸããã¹ããŒããã©ã³ãã¿ãã¬ãããããœã³ã³ãã²ãŒã æ©ãªã©ãWi-Fiã«æ¥ç¶ããå šãŠã®ããã€ã¹ãDHCPã®ã¯ã©ã€ã¢ã³ããšãªããã«ãŒã¿ããIPã¢ãã¬ã¹ãååŸããŸãã
ãã®ã·ã¹ãã ã®ãããã§ãæã ã¯åããã€ã¹ã®ãããã¯ãŒã¯èšå®ãæ°ã«ããããšãªããç°¡åã«ã€ã³ã¿ãŒãããã«æ¥ç¶ããããšãã§ããŸããç¹ã«ã蚪åè ãæã ã®ãããã¯ãŒã¯ã«äžæçã«æ¥ç¶ããå ŽåãDHCPã¯ãã®éçšã倧ãã«ç°¡çŽ åããŸãã
6.2 äŒæ¥å ã®ãããã¯ãŒã¯
äŒæ¥ã®ãªãã£ã¹å ã§ããDHCPã¯æ¬ ãããªãããŒã«ã§ããäŒæ¥ãããã¯ãŒã¯ã§ã¯ã瀟å¡ã®ããœã³ã³ãã¢ãã€ã«ããã€ã¹ãããªã³ã¿ãVoIPé»è©±ãªã©ãæ°å€ãã®ããã€ã¹ããããã¯ãŒã¯ã«æ¥ç¶ããŸãããããå šãŠã®ããã€ã¹ã«IPã¢ãã¬ã¹ãæåã§å²ãåœãŠãããšã¯ãæéãšåŽåã®å€§å¹ ãªæµªè²»ãæå³ããŸãã
ãã®ãããäŒæ¥ã§ã¯éåžžãäžå€®ã®ãããã¯ãŒã¯ãµãŒãã«DHCPãµãŒããèšçœ®ããå šãŠã®ããã€ã¹ãèªåçã«IPã¢ãã¬ã¹ãååŸã§ããããã«ããŸãããŸãããããã¯ãŒã¯ã®å®å šæ§ã確ä¿ããããã«ãMACã¢ãã¬ã¹ã«åºã¥ããŠç¹å®ã®ããã€ã¹ã®ã¿ã«IPã¢ãã¬ã¹ãå²ãåœãŠããããªèšå®ãå¯èœã§ãã
7. DHCPã®ãã©ãã«ã·ã¥ãŒãã£ã³ã°
7.1 ããããåé¡ãšè§£æ±ºæ¹æ³
DHCPã¯ãããã¯ãŒã¯ã®éèŠãªéšåãæ ã£ãŠãããããåé¡ãçºçããå Žåãããã¯ãããã¯ãŒã¯æ¥ç¶ã®ãã©ãã«ãšããŠçŸããŸãã以äžã«ãäžè¬çãªDHCPé¢é£ã®åé¡ãšãã®è§£æ±ºçãããã€ã玹ä»ããŸãã
1. IPã¢ãã¬ã¹ãååŸã§ããªã: ãã®åé¡ã®äžè¬çãªåå ã¯DHCPãµãŒãã®ããŠã³ã¿ã€ã ããŸãã¯ãããã¯ãŒã¯äžã®ä»ã®åé¡ã§ããããã解決ããããã«ã¯ããŸãã«ãŒã¿ãDHCPãµãŒããåèµ·åãããããåé¡ã解決ããªãå Žåã¯ããããã¯ãŒã¯æ¥ç¶ã確èªããããšãæ±ããããŸãã
2. IPã¢ãã¬ã¹ã®ç«¶å: 2ã€ã®ããã€ã¹ãåãIPã¢ãã¬ã¹ãæã€ãšãIPã¢ãã¬ã¹ã®ç«¶åãçºçããŸããããã¯äžè¬çã«ãæåã§èšå®ãããéçIPãšDHCPã«ãã£ãŠå²ãåœãŠãããIPã®éã§èµ·ãããŸãããã®åé¡ã解決ããããã«ã¯ã競åããŠããIPã¢ãã¬ã¹ãæã€ããã€ã¹ã®èšå®ã確èªããå¿ èŠã«å¿ããŠå€æŽããŸãã
3. DHCPãµãŒããç¯å²å€ã®IPã¢ãã¬ã¹ãå²ãåœãŠã: DHCPãµãŒããèšå®ç¯å²å€ã®IPã¢ãã¬ã¹ãå²ãåœãŠãŠããŸãå Žåããã®ããã€ã¹ã¯ãããã¯ãŒã¯ã«é©åã«æ¥ç¶ã§ããŸããããã®åé¡ã解決ããããã«ã¯ãDHCPãµãŒãã®èšå®ã確èªããæ£ããIPã¢ãã¬ã¹ç¯å²ãèšå®ãããŠããããšã確èªããå¿ èŠããããŸãã
ãããã®äžè¬çãªåé¡ãç解ãããããã«å¯ŸåŠããããšã§ãDHCPãçšãããããã¯ãŒã¯éçšãããã¹ã ãŒãºã«è¡ãããšãå¯èœã«ãªããŸãã
8. ãŸãšã
8.1 DHCPã®éèŠæ§
ä»åã®èšäºãéããŠãDHCPã®åºæ¬æŠå¿µãããã®å®çšçãªå©çšæ³ãããã«ã¯ãã©ãã«ã·ã¥ãŒãã£ã³ã°ãŸã§ã詳ããåŠã³ãŸããããããã¯ãŒã¯æè¡ã¯ããžã¿ã«å瀟äŒãæ¯ããåºç€ãšãªã£ãŠããããã®äžã§ãDHCPã¯ããã€ã¹ããããã¯ãŒã¯ã«æ¥ç¶ããããã«å¿ èŠäžå¯æ¬ ãªãµãŒãã¹ã§ãã
DHCPã®èœåã«ãããIPã¢ãã¬ã¹ã®æåèšå®ã管çã®æéãå€§å¹ ã«æžå°ãããããã¯ãŒã¯ç°å¢ã®èšå®ãèªååãããŸããããã«ãã£ãŠå¹çæ§ãåäžãããŠãŒã¶ãŒãšã¯ã¹ããªãšã³ã¹ãæ¹åããŸãããã ããDHCPã®æ©èœãæ£ããåäœããªããšãããã¯ãŒã¯å šäœã«åœ±é¿ãåãŒãå¯èœæ§ããããããé©åãªç解ãšéçšãæ±ããããŸãã
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