Kafin mu fara koyawa ta bidiyo ta yau, ina so in gode wa duk wanda ya ba da gudummawa ga shaharar kwas na a YouTube. Lokacin da na fara shi kimanin watanni 8 da suka gabata, ban yi tsammanin irin wannan nasarar ba - a yau mutane 312724 sun kalli darasina, ina da masu biyan kuɗi 11208. Ban taba mafarkin cewa wannan kaskanci na farko zai kai irin wannan matsayi ba. Amma kada mu bata lokaci mu kai ga darasin yau. A yau za mu cike gibin da ya faru a darussan bidiyo 7 na karshe. Duk da cewa yau rana ta 6 ce kawai, rana ta 3 ta rabu gida biyu darussan bidiyo 3, don haka a yau za ku kalli darasin bidiyo na takwas.
A yau za mu rufe muhimman batutuwa guda 3: DHCP, sufuri na TCP, da kuma mafi yawan lambobin tashar jiragen ruwa. Mun riga mun yi magana game da adiresoshin IP, kuma ɗayan mahimman abubuwan da ke cikin tsarin adireshin IP shine DHCP.
DHCP yana tsaye ga Ƙa'idar Kanfigareshan Mai watsa shiri mai ƙarfi kuma ƙa'ida ce da ke taimakawa daidaita adiresoshin IP ga runduna. Don haka duk mun ga wannan taga. Lokacin da ka danna zaɓin "Sami adireshin IP ta atomatik", kwamfutar tana neman uwar garken DHCP wanda aka saita akan rukunin yanar gizon guda ɗaya kuma ta aika fakiti daban-daban da buƙatun adireshin IP. Ka'idar DHCP tana da saƙonni 6, waɗanda 4 ke da mahimmanci don sanya adireshin IP.
Saƙon farko shine saƙon GANO na DHCP. Sakon gano DHCP yayi kama da saƙon gaisuwa. Lokacin da sabuwar na'ura ta shiga cibiyar sadarwar, tana tambaya ko akwai uwar garken DHCP akan hanyar sadarwar.
Abin da kuke gani a cikin nunin yana kama da buƙatar watsa shirye-shirye inda na'urar ke tuntuɓar duk na'urorin da ke kan hanyar sadarwa suna neman sabar DHCP. Kamar yadda na ce, wannan buƙatun watsa shirye-shirye ne, don haka duk na'urorin da ke kan hanyar sadarwa za su iya ji ta.
Idan akwai uwar garken DHCP akan hanyar sadarwar, tana aika fakiti - tayin DHCP OFFER. Shawara tana nufin cewa uwar garken DHCP, don amsa buƙatun ganowa, ta aika da tsari ga abokin ciniki, yana tambayar abokin ciniki ya karɓi takamaiman adireshin IP.
Sabar DHCP ta tanadi adireshin IP, a wannan yanayin 192.168.1.2, baya samar da ita, sai dai ta tanadi wannan adireshin don na'urar. A lokaci guda, kunshin tayin ya ƙunshi adireshin IP ɗin sa na uwar garken DHCP.
Idan akwai sabar DHCP fiye da ɗaya akan wannan hanyar sadarwa, wata uwar garken DHCP, bayan karɓar buƙatar watsa shirye-shiryen abokin ciniki, kuma zata ba shi adireshin IP ɗin sa, misali, 192.168.1.50. Ba kowa ba ne don saita sabar DHCP daban-daban guda biyu akan hanyar sadarwa iri ɗaya, amma wani lokacin yana faruwa. Don haka lokacin da aka aika tayin DHCP ga abokin ciniki, yana karɓar tayin DHCP 2 kuma dole ne yanzu ya yanke shawarar wacce tayin DHCP yake son karɓa.
Bari mu ɗauka abokin ciniki ya karɓi aikace-aikacen farko. Wannan yana nufin cewa abokin ciniki ya aika buƙatun DHCP wanda a zahiri ya ce "Na karɓi adireshin IP 192.168.1.2 wanda uwar garken DHCP 192.168.1.1 ke bayarwa."
Bayan karɓar buƙatar, uwar garken 192.168.1.1 DHCP ta amsa "lafiya, na yarda," wato, ta yarda da buƙatar kuma ta aika da wannan DHCP ACK ga abokin ciniki. Amma mun tuna cewa wani uwar garken DHCP ya tanadi adireshin IP na 1.50 ga abokin ciniki. Da zarar ya karɓi buƙatun watsa shirye-shiryen abokin ciniki, zai san game da gazawar kuma zai mayar da adireshin IP a cikin tafkin domin ya sanya shi ga wani abokin ciniki idan ya karɓi wani buƙatun.
Waɗannan su ne mahimman saƙonni guda 4 waɗanda DHCP ke musanya yayin sanya adiresoshin IP. Bayan haka, DHCP yana da ƙarin saƙonnin bayanai guda 2. Abokin ciniki yana fitar da saƙon bayanai idan yana buƙatar ƙarin bayani fiye da wanda aka karɓa a cikin magana ta DHCP OFFER a mataki na biyu. Idan uwar garken bai samar da isassun bayanai ba a cikin tayin DHCP, ko kuma idan abokin ciniki yana buƙatar ƙarin bayani fiye da abin da ke ƙunshe a cikin fakitin tayin, yana buƙatar ƙarin bayanin DHCP. Akwai ƙarin saƙo ɗaya wanda abokin ciniki ya aika zuwa uwar garken - wannan shine SAKI na DHCP. Yana sanar da ku cewa abokin ciniki yana so ya saki adireshin IP ɗin da yake yanzu.
Koyaya, abin da ya fi faruwa sau da yawa shine mai amfani ya katse haɗin yanar gizo kafin abokin ciniki ya sami lokacin aika SAKI na DHCP zuwa uwar garken. Wannan yana faruwa lokacin da kuka kashe kwamfutar, wanda muke yi. A wannan yanayin, abokin ciniki na cibiyar sadarwa, ko kwamfuta, kawai ba su da lokacin sanar da uwar garken don sakin adireshin da aka yi amfani da shi, don haka SAKI na DHCP ba matakin da ake buƙata ba ne. Matakan da ake buƙata don samun adireshin IP sune: gano DHCP, tayin DHCP, buƙatar DHCP, da musafaha DHCP.
A cikin ɗayan darussa na gaba zan gaya muku yadda muke saita uwar garken DHCP lokacin ƙirƙirar tafkin DNCP. Ta haɗawa muna nufin cewa ka gaya wa uwar garken don sanya adiresoshin IP a cikin kewayon 192.168.1.1 zuwa 192.168.1.254. Don haka, uwar garken DHCP za ta ƙirƙiri tafkin, sanya adiresoshin IP 254 a ciki, kuma za su iya sanya adireshi ga abokan ciniki a kan hanyar sadarwa kawai daga wannan tafkin. Don haka wannan wani abu ne kamar tsarin gudanarwa wanda mai amfani zai iya yi.
Yanzu bari mu dubi TCP watsa. Ban sani ba ko kun saba da "wayar tarho" da ke hoton hoton, amma lokacin da muke yara muna amfani da waɗannan gwangwani da aka haɗa da igiya don yin magana da juna.
Abin baƙin ciki shine, tsararrakin yau ba za su iya samun irin wannan "alatu" ba. Ina nufin a yau yara suna gaban TV tun suna shekara ɗaya, suna wasan PSP kuma watakila wannan abin zance ne amma ina tsammanin muna da mafi kyawun yara, mun fita waje muna yin wasanni kuma yaran yau ba za a iya janye su daga gadon gado ba. .
Ɗana yana ɗan shekara ɗaya kuma na riga na ga ya kamu da iPad, ina nufin har yanzu yana ƙarami amma ina tsammanin yaran yau sun riga sun san yadda ake sarrafa na'urorin lantarki. Don haka, ina so in ce mu yara, idan muna wasa, sai mu yi ramuka a cikin gwangwani, idan muka ɗaure su da igiya, mu ce wani abu a cikin gwangwani ɗaya, a gefe guda kuma mutum yana jin abin da ake faɗa. gareshi, kawai ta hanyar saka gwangwani a kunnensa . Don haka yana kama da haɗin yanar gizo.
A yau, ko da canja wurin TCP dole ne ya sami hanyar haɗi wanda dole ne a kafa kafin ainihin canja wurin bayanai ya fara. Kamar yadda muka tattauna a cikin darussan da suka gabata, TCP shine watsawa ta hanyar haɗin kai yayin da UDP ke watsa hanyoyin sadarwa. Kuna iya cewa UDP ne inda na jefa kwallon kuma ya rage na ku don ganin ko za ku iya kama ta. Ko kin shirya ko kin shirya ba shine matsalata ba, zan barshi kawai.
TCP ya fi zama kamar ka yi magana da saurayi kuma ka gargade shi a gaba cewa za ka jefa kwallo, don haka ka kulla yarjejeniya, sannan ka jefa kwallon don abokin tarayya ya kasance a shirye ya kama ta. Don haka TCP a zahiri yana gina haɗin gwiwa sannan ya fara yin ainihin watsawa.
Bari mu dubi yadda yake haifar da irin wannan haɗin. Wannan ƙa'idar tana amfani da musafaha na hanyoyi 3 don ƙirƙirar haɗi. Wannan ba kalmar fasaha ba ce, amma an daɗe ana amfani da ita don kwatanta haɗin TCP. Na'urar aikewa ce ta fara yin musafaha mai-hanyoyi 3, tare da abokin ciniki ya aika fakiti mai alamar SYN zuwa uwar garken.
A ce yarinyar da ke gaba, wacce za mu iya ganin fuskarta, ita ce device A, kuma yarinyar da ke bayanta, wacce ba a ganin fuskarta, ita ce Device B. Girl A ta aika wa yarinya B takardar SYN, sai ta ce: "Mai girma, wanda ya ke so ya yi magana da ni. Don haka, ina buƙatar amsa cewa na shirya don sadarwa! ” Yadda za a yi? Mutum zai iya kawai aika wani fakitin SYN sannan kuma ACK mai nuni da samun ainihin fakitin SYN. Amma maimakon aika ACKs daban, uwar garken ta samar da fakiti na gama-gari wanda ke dauke da SYN da ACK kuma suna watsa shi ta hanyar sadarwar.
Don haka a wannan lokacin, na'urar A ta aika fakitin SYN kuma ta karɓi fakitin SYN/ACK. Yanzu dole ne na'urar A ta aika na'urar B fakitin ACK, wato, tabbatar da cewa ta karɓi izini daga na'urar B don kafa sadarwa. Don haka, duka na'urorin biyu sun sami fakitin SYN da ACK, kuma yanzu muna iya cewa an kafa haɗin gwiwa, wato, an kammala musabaha mai matakai 3 ta hanyar amfani da ka'idar TCP.
Na gaba za mu kalli fasahar Windowing TCP. A taƙaice, hanya ce da ake amfani da ita a cikin TCP/IP don yin shawarwari akan iyawar mai aikawa da mai karɓa.
Bari mu ce a cikin Windows muna ƙoƙarin canja wurin babban fayil, faɗi girman 2 GB, daga wannan tuƙi zuwa wancan. A farkon canja wurin, tsarin zai sanar da mu cewa canja wurin fayil zai ɗauki kimanin shekara 1. Amma bayan 'yan dakiku tsarin zai gyara kansa ya ce: "Oh, jira minti daya, ina tsammanin zai ɗauki kimanin watanni 6, ba shekara guda ba." Wani ɗan lokaci kaɗan zai wuce kuma Windows zai ce: "Ina tsammanin zan iya canja wurin fayil ɗin a cikin wata 1." Wannan zai biyo bayan saƙon "rana 1", "awanni 6", "awanni 3", "awa 1", "minti 20", "minti 10", "minti 3". A zahiri, duk aikin canja wurin fayil zai ɗauki mintuna 3 kawai. Ta yaya hakan ya faru? Da farko, lokacin da na'urarka ta yi ƙoƙarin sadarwa tare da wata na'ura, ta aika fakiti ɗaya tana jiran tabbaci. Idan na'urar ta jira dogon lokaci don tabbatarwa, tana tunanin: "Idan dole ne in canja wurin 2 GB na bayanai a wannan saurin, zai ɗauki kimanin shekaru 2." Bayan wani lokaci, na'urarka ta karɓi ACK kuma tana tunanin, “lafiya, na aika fakiti ɗaya na karɓi ACK, don haka mai karɓa zai iya karɓar fakiti 1. Yanzu zan yi ƙoƙarin aika masa fakiti 10 maimakon ɗaya.” Mai aikawa ya aika da fakiti 10 kuma bayan wani lokaci ya sami tabbacin ACK daga na'urar karɓa, wanda ke nufin cewa mai karɓa yana jiran fakiti na 11 na gaba. Mai aikawa ya yi tunani: “Madalla, tun da wanda aka karɓa ya ɗauki fakiti 10 a lokaci ɗaya, yanzu zan yi ƙoƙarin aika masa fakiti 100 maimakon goma.” Ya aika fakiti 100, kuma mai karɓa ya amsa cewa ya karɓa kuma yanzu yana jiran fakiti 101. Don haka, bayan lokaci, adadin fakitin da aka watsa yana ƙaruwa.
Wannan shine dalilin da ya sa kuke ganin raguwa cikin sauri a lokacin kwafin fayil idan aka kwatanta da abin da aka bayyana a asali - wannan ya faru ne saboda karuwar ikon canja wurin bayanai masu yawa. Koyaya, akwai ma'ana lokacin da ƙarin haɓaka ƙarar watsawa ya zama ba zai yiwu ba. A ce kun aika fakiti 10000, amma na'urar buffer na na'urar tana iya karɓar 9000 kawai. Daga wannan, mai aikawa ya kammala cewa buffer na na'urar yana da karfin 9000 kawai, wanda ke nufin cewa daga yanzu ba zan aika da fakiti fiye da 9001 ba a lokaci guda. A wannan yanayin, mai aikawa da sauri ya ƙididdige lokacin da zai ɗauke shi don canja wurin sauran adadin bayanai a cikin sassan 9000, ya ba da minti 9000. Waɗannan mintuna uku sune ainihin lokacin watsawa. Abin da TCP Windowing ke yi.
Wannan yana ɗaya daga cikin waɗannan hanyoyin tururuwa inda na'urar aika a ƙarshe ta fahimci menene ainihin ƙarfin cibiyar sadarwa. Kuna iya yin mamakin dalilin da yasa ba za su iya yarda da gaba ba akan menene ƙarfin na'urar karba? Gaskiyar ita ce, wannan ba zai yuwu a fasaha ba saboda akwai nau'ikan na'urori daban-daban akan hanyar sadarwa. Bari mu ce kana da iPad kuma yana da saurin canja wurin bayanai/karɓar bayanai daban-daban fiye da iPhone, ƙila kana da nau'ikan wayoyi daban-daban, ko wataƙila kana da tsohuwar kwamfuta. Saboda haka, kowa yana da bandwidth na cibiyar sadarwa daban-daban.
Wannan shine dalilin da ya sa aka haɓaka fasahar TCP Windowing, lokacin da watsa bayanai ke farawa da ƙaramin sauri ko tare da watsa mafi ƙarancin fakiti, sannu a hankali yana haɓaka zirga-zirga "taga". Kuna aika fakiti ɗaya, fakiti 5, fakiti 10, fakiti 1000, fakiti 10000 kuma sannu a hankali buɗe waccan taga har sai “buɗe” ya kai matsakaicin yuwuwar yawan zirga-zirgar zirga-zirgar da aka aika a cikin takamaiman lokaci. Don haka, manufar Windowing wani bangare ne na aikin ka'idar TCP.
Na gaba za mu dubi mafi yawan lambobin tashar jiragen ruwa. Yanayin al'ada shine lokacin da kake da babban uwar garken 1, watakila cibiyar bayanai. Ya haɗa da uwar garken fayil, sabar gidan yanar gizo, sabar saƙo da sabar DHCP. Yanzu, idan ɗaya daga cikin kwamfutocin abokin ciniki ya tuntuɓi cibiyar bayanai, wanda ke tsakiyar hoton, zai fara aika zirga-zirgar sabar fayil zuwa na'urorin abokin ciniki. Ana nuna wannan zirga-zirgar cikin ja kuma za a watsa shi akan takamaiman tashar jiragen ruwa don takamaiman aikace-aikacen daga takamaiman sabar.
Ta yaya uwar garken ta san inda wasu zirga-zirgar zirga-zirgar ya kamata su je? Ya koyi wannan daga lambar tashar tashar jirgin ruwa. Idan ka dubi firam ɗin, za ka ga cewa a cikin kowane canja wurin bayanai akwai ambaton lambar tashar tashar jiragen ruwa da lambar tashar tashar tushe. Kuna iya ganin cewa zirga-zirgar shuɗi da ja, da kuma zirga-zirgar shuɗi shine zirga-zirgar sabar gidan yanar gizo, duka suna zuwa uwar garken jiki iri ɗaya, wanda aka sanya sabobin daban-daban. Idan wannan cibiyar bayanai ce, to tana amfani da sabobin kama-da-wane. To ta yaya suka san cewa jajayen zirga-zirgar ya kamata su koma waccan kwamfutar tafi-da-gidanka ta hagu mai adireshin IP? Sun san wannan godiya ga lambobin tashar jiragen ruwa. Idan ka koma zuwa labarin Wikipedia "Jerin TCP da UDP Ports", za ka ga cewa ya jera duk daidaitattun lambobin tashar jiragen ruwa.
Idan ka gungurawa wannan shafin zaka iya ganin girman girman wannan jeri. Ya ƙunshi kusan lambobi 61. Lambobin tashar jiragen ruwa daga 000 zuwa 1 an san su da lambobin tashar jiragen ruwa da aka fi sani. Misali, tashar jiragen ruwa 1024/TCP shine don aika umarni na ftp, tashar jiragen ruwa 21 na ssh, tashar jiragen ruwa 22 na Telnet ne, wato don aika saƙonnin da ba a ɓoye ba. Shahararriyar tashar jiragen ruwa 23 tana ɗaukar bayanai akan HTTP, yayin da tashar jiragen ruwa 80 ke ɗaukar bayanan ɓoye akan HTTPS, wanda yayi kama da amintaccen sigar HTTP.
An sadaukar da wasu tashoshin jiragen ruwa ga duka TCP da UDP, wasu kuma suna yin ayyuka daban-daban dangane da ko haɗin TCP ne ko UDP. Don haka, a hukumance TCP tashar jiragen ruwa 80 ana amfani da HTTP, kuma UDP tashar jiragen ruwa 80 ana amfani da HTTP ba bisa ka'ida ba, amma ƙarƙashin wata yarjejeniya ta HTTP daban - QUIC.
Saboda haka, lambobin tashar jiragen ruwa a cikin TCP ba koyaushe ake nufin yin abu ɗaya kamar na UDP ba. Ba kwa buƙatar koyon wannan jeri da zuciya ɗaya, ba zai yuwu a tuna ba, amma kuna buƙatar sanin wasu shahararrun lambobin tashar jiragen ruwa na gama gari. Kamar yadda na fada, wasu daga cikin wadannan tashoshin jiragen ruwa suna da wata manufa ta hukuma, wacce aka bayyana a cikin ma'auni, wasu kuma suna da manufar da ba na hukuma ba, kamar yadda yake da Chromium.
Don haka, wannan tebur yana lissafin duk lambobin tashar jiragen ruwa na gama gari, kuma ana amfani da waɗannan lambobin don aikawa da karɓar zirga-zirga lokacin amfani da takamaiman aikace-aikace.
Yanzu bari mu dubi yadda bayanai ke tafiya a cikin hanyar sadarwa bisa ga ƙananan bayanan da muka sani. Bari mu ce kwamfuta 10.1.1.10 tana son tuntuɓar wannan kwamfutar, ko kuma wannan uwar garken, mai adireshin 30.1.1.10. A ƙasa adireshin IP na kowace na'ura akwai adireshin MAC. Ina ba da misalin adireshin MAC mai haruffa 4 na ƙarshe kawai, amma a aikace yana da lambar hexadecimal 48-bit mai haruffa 12. Tunda kowane ɗayan waɗannan lambobin ya ƙunshi 4 ragowa, lambobi 12 hexadecimal suna wakiltar lamba 48-bit.
Kamar yadda muka sani, idan wannan na'urar tana son tuntuɓar wannan uwar garken, mataki na farko na musafaha-hanyoyi 3 dole ne a fara yi, wato aika fakitin SYN. Lokacin da aka yi wannan buƙatar, kwamfutar 10.1.1.10 za ta ƙayyade lambar tashar tashar ruwa, wanda Windows ke ƙirƙira a hankali. Windows ba da gangan ya zaɓi lambar tashar jiragen ruwa tsakanin 1 zuwa 65,000 ba. Amma tun da farawa lambobi a cikin kewayon 1 zuwa 1024 sun shahara sosai, a wannan yanayin tsarin zai yi la'akari da lambobi sama da 25000 kuma ya ƙirƙiri tashar tashar tashar bazuwar, misali, lamba 25113.
Bayan haka, tsarin zai ƙara tashar tashar jiragen ruwa zuwa fakitin, a wannan yanayin shine tashar jiragen ruwa 21, saboda aikace-aikacen da ke ƙoƙarin haɗi zuwa uwar garken FTP ya san cewa ya kamata ya aika da zirga-zirgar FTP.
Na gaba, kwamfutarmu ta ce, "Ok, adireshin IP na 10.1.1.10, kuma ina buƙatar tuntuɓar adireshin IP 30.1.1.10." Duk waɗannan adireshi kuma ana haɗa su a cikin fakiti don samar da buƙatar SYN, kuma wannan fakitin ba zai canza ba har sai ƙarshen haɗin.
Ina so ku gane daga wannan bidiyon yadda bayanai ke tafiya a cikin hanyar sadarwa. Lokacin da kwamfutarmu da ke aika buƙatun ta ga adireshin IP na tushen da adireshin IP ɗin da za a nufa, ta fahimci cewa adireshin wurin ba a kan hanyar sadarwar gida yake ba. Na manta cewa waɗannan duka /24 adiresoshin IP ne. Don haka idan ka duba adireshin IP na /24, za ka gane cewa kwamfutoci 10.1.1.10 da 30.1.1.10 ba su kan hanyar sadarwa daya. Don haka, kwamfutar da ke aika buƙatun ta fahimci cewa don barin wannan hanyar sadarwa, dole ne ta tuntuɓi ƙofar 10.1.1.1, wanda aka saita akan ɗayan hanyoyin sadarwa na na'ura mai ba da hanya tsakanin hanyoyin sadarwa. Ya san cewa ya kamata ya je 10.1.1.1 kuma ya san adireshin MAC na 1111, amma bai san adireshin MAC na ƙofar 10.1.1.1 ba. Me yake yi? Yana aika buƙatun ARP na watsa shirye-shiryen cewa duk na'urorin da ke kan hanyar sadarwar za su karɓa, amma na'ura mai ba da hanya tsakanin hanyoyin sadarwa tare da adireshin IP 10.1.1.1 kawai zai amsa shi.
Na'ura mai ba da hanya tsakanin hanyoyin sadarwa zai amsa tare da adireshin MAC na AAAA, kuma duka tushen da adireshin MAC ɗin kuma za a sanya su a cikin wannan firam. Da zarar firam ɗin ya shirya, za a yi binciken amincin bayanan CRC, wanda shine algorithm don nemo adadin kuɗi don gano kurakurai, kafin barin hanyar sadarwar.
Cyclic Redundancy CRC yana nufin cewa gabaɗayan wannan firam, daga SYN zuwa adireshin MAC na ƙarshe, ana gudanar da shi ta hanyar hashing algorithm, in ji MD5, yana haifar da ƙimar zanta. Ƙimar zanta, ko MD5 checksum, sannan ana sanya shi a farkon firam.
Na yi masa lakabi da FCS/CRC saboda FCS Semalt Check Sequence ne, ƙimar CRC mai byte huɗu. Wasu mutane suna amfani da sunan FCS wasu kuma suna amfani da nadi CRC, don haka kawai na haɗa duka zayyana. Amma a zahiri ƙima ce kawai. Ana buƙatar tabbatar da cewa duk bayanan da aka karɓa akan hanyar sadarwar ba su ƙunshi kurakurai ba. Don haka, lokacin da wannan firam ɗin ya isa na'ura mai ba da hanya tsakanin hanyoyin sadarwa, abu na farko da na'ura mai ba da hanya tsakanin hanyoyin sadarwa zai yi shi ne lissafin checksum da kansa ya kwatanta shi da ƙimar FCS ko CRC wanda firam ɗin da aka karɓa ya ƙunshi. Ta wannan hanyar zai iya duba cewa bayanan da aka karɓa ta hanyar sadarwar ba su ƙunshi kurakurai ba, bayan haka zai cire checksum daga firam.
Na gaba, na'ura mai ba da hanya tsakanin hanyoyin sadarwa zai duba adireshin MAC kuma ya ce, "Ok, adireshin MAC na AAAA yana nufin firam ɗin yana magana da ni," kuma ya share ɓangaren firam ɗin da ke ɗauke da adiresoshin MAC.
Duban adireshin IP ɗin da ake nufi 30.1.1.10, zai fahimci cewa wannan fakitin ba a yi masa magana ba kuma dole ne ya ci gaba ta hanyar na'ura mai ba da hanya tsakanin hanyoyin sadarwa.
Yanzu na'ura mai ba da hanya tsakanin hanyoyin sadarwa "yana tunanin" yana buƙatar ganin inda cibiyar sadarwa tare da adireshin 30.1.1.10 yake. Har yanzu ba mu rufe cikakken ra'ayi na zirga-zirgar ababen hawa ba tukuna, amma mun san cewa masu amfani da hanyar sadarwa suna da tebur mai tuƙi. Wannan tebur yana da shigarwa don hanyar sadarwa tare da adireshin 30.1.1.0. Kamar yadda kuke tunawa, wannan ba adireshin IP ɗin mai masauki bane, amma mai gano hanyar sadarwa. Mai na'ura mai ba da hanya tsakanin hanyoyin sadarwa zai "tunani" cewa zai iya isa adireshin 30.1.1.0/24 ta hanyar hanyar sadarwa 20.1.1.2.
Kuna iya tambaya, ta yaya ya san wannan? Kawai ka tuna cewa zai san wannan ko dai daga ka'idojin zirga-zirga ko kuma daga saitunan ku idan ku a matsayin mai gudanarwa kun tsara madaidaiciyar hanya. Amma a kowane hali, teburin wannan na'ura mai ba da hanya tsakanin hanyoyin sadarwa yana dauke da madaidaicin shigarwa, don haka ya san ya kamata ya aika wannan fakiti zuwa 20.1.1.2. A zaton cewa na'ura mai ba da hanya tsakanin hanyoyin sadarwa ya riga ya san adireshin MAC na manufa, za mu ci gaba da tura fakitin kawai. Idan bai san wannan adireshin ba, zai sake farawa ARP, karɓar adireshin MAC na mai ba da hanya tsakanin hanyoyin sadarwa 20.1.1.2, kuma tsarin aika firam ɗin zai sake ci gaba.
Don haka muna ɗauka cewa ya riga ya san adireshin MAC, to, za mu sami adireshin MAC na tushen BBB da adireshin MAC na tashar CCC. Mai ba da hanya tsakanin hanyoyin sadarwa ya sake lissafin FCS/CRC kuma ya sanya shi a farkon firam.
Daga nan sai ta aika da wannan firam a kan hanyar sadarwa, firam ɗin ya kai 20.1.12 na na'ura mai ba da hanya tsakanin hanyoyin sadarwa, yana duba checksum, ya tabbatar da cewa bayanan ba su lalace ba, kuma ya goge FCS/CRC. Yana sa'an nan "truncates" da MAC adiresoshin, ya dubi manufa da kuma ganin cewa shi ne 30.1.1.10. Ya san cewa wannan adireshi yana da alaƙa da haɗin gwiwar sa. Ana maimaita tsarin samar da firam iri ɗaya, na'ura mai ba da hanya tsakanin hanyoyin sadarwa tana ƙara tushen da ƙimar adireshin adireshin MAC, yana yin hashing, haɗa zanta zuwa firam ɗin kuma aika shi cikin hanyar sadarwa.
Sabar tamu, daga ƙarshe ta karɓi buƙatar SYN da aka yi mata, tana bincika mashin ɗin hash, kuma idan fakitin bai ƙunshi kurakurai ba, yana goge zaren. Sannan ya cire adireshin MAC, ya duba adireshin IP kuma ya gane cewa wannan fakitin an aika masa da shi.
Bayan haka, yana yanke adiresoshin IP masu alaƙa da Layer na uku na samfurin OSI kuma yana duba lambobin tashar jiragen ruwa.
Yana ganin tashar jiragen ruwa 21, wanda ke nufin zirga-zirgar FTP, yana ganin SYN kuma saboda haka ya fahimci cewa wani yana ƙoƙarin sadarwa da shi.
Yanzu, bisa ga abin da muka koya game da musafaha, uwar garken 30.1.1.10 zai ƙirƙiri fakitin SYN/ACK kuma ya mayar da shi zuwa kwamfuta 10.1.1.10. Bayan samun wannan fakitin, na'urar 10.1.1.10 za ta ƙirƙiri ACK, ta wuce ta hanyar sadarwar kamar yadda fakitin SYN, kuma bayan uwar garken ta karɓi ACK, haɗin haɗin zai kasance.
Abu daya da ya kamata ku sani shine duk wannan yana faruwa a cikin ƙasa da daƙiƙa guda. Wannan tsari ne mai matukar sauri, wanda na yi kokarin rage gudu don komai ya bayyana a gare ku.
Ina fatan za ku sami abin da kuka koya a cikin wannan koyawa yana da amfani. Idan kuna da tambayoyi, da fatan za a rubuto mani a [email kariya] ko barin tambayoyi a ƙarƙashin wannan bidiyo.
Fara da darasi na gaba, zan zaɓi tambayoyi 3 mafi ban sha'awa daga YouTube, waɗanda zan sake dubawa a ƙarshen kowane bidiyo. Daga yanzu zan sami sashin "Top Questions" don haka zan buga tambaya tare da sunan ku kuma in amsa ta kai tsaye. Ina ganin wannan zai yi amfani.
Na gode da kasancewa tare da mu. Kuna son labaran mu? Kuna son ganin ƙarin abun ciki mai ban sha'awa? Goyon bayan mu ta hanyar ba da oda ko ba da shawara ga abokai, Rangwamen 30% ga masu amfani da Habr akan keɓaɓɓen analogue na sabar matakin shigarwa, wanda mu muka ƙirƙira muku: (akwai tare da RAID1 da RAID10, har zuwa 24 cores kuma har zuwa 40GB DDR4).
VPS (KVM) E5-2650 v4 (6 Cores) 10GB DDR4 240GB SSD 1Gbps kyauta har zuwa bazara lokacin biya na tsawon watanni shida, zaka iya yin oda .
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source: www.habr.com