Kugadzika kweTCP Connection
Patinotarisa pawebhu, kutumira email, kana kutamba mutambo wepamhepo, hatiwanzo funga nezve network connection yakaoma iri shure kwayo. Zvisinei, matanho aya anoita sediki ndiwo anoita kuti pave nekutaurirana kwakasimba pakati pedu neserver. Imwe yematanho akakosha ndeye TCP connection setup, uye chinangwa chikuru cheizvi ndechekubatana maoko nenzira nhatu.
Chinyorwa chino chichakurukura zvakadzama musimboti, maitiro uye kukosha kwekubatana kwemaoko nenzira nhatu. Danho nedanho, tichatsanangura kuti nei kubatana kwemaoko nenzira nhatu kuchidikanwa, kuti kunovimbisa sei kugadzikana uye kuvimbika kwekubatana, uye kukosha kwacho pakutumira data. Nekunzwisisa kwakadzama kwekubatana kwemaoko nenzira nhatu, tichanzwisisa zviri nani nzira dziripo dzekutaurirana kwenetiweki uye kuona zvakajeka kuvimbika kwekubatana kweTCP.
Maitiro eTCP Three-way Handshake uye State Transitions
TCP inzira yekufambisa inoenderana nekubatana, iyo inoda kugadzwa kwekubatana usati watumira data. Maitiro aya ekugadzira kubatana anoitwa nekubatana maoko kwemativi matatu.
Ngatinyatsoongorora mapaketi eTCP anotumirwa mukubatanidza kwega kwega.
Pakutanga, mutengi neseva zvese zvavharwa. Kutanga, sevha inoteerera zviri nyore pachiteshi uye iri muchimiro cheLISTEN, zvinoreva kuti sevha inofanira kutanga. Tevere, mutengi anenge agadzirira kutanga kupinda pawebhusaiti. Inofanira kutanga kubatana nesevha. Mafomati epaketi yekutanga yekubatanidza ndeaya anotevera:
Kana mutengi atanga kubatana, anogadzira nhamba yekutanga yekutevera isina kurongeka (client_isn) uye anoiisa mu "Sequence number" yeTCP header. Panguva imwe chete, mutengi anoisa chinzvimbo cheSYN flag ku1 kuratidza kuti packet iri kubuda iSYN packet. Mutengi anoratidza kuti anoda kutanga kubatana neserver nekutumira packet yekutanga yeSYN kuserver. Packet iyi haina data re application layer (ndiko kuti, data rakatumirwa). Panguva ino, mamiriro emutengi akanyorwa seSYN-SENT.
Kana sevha ikagamuchira packet yeSYN kubva kumutengi, inotanga nhamba yayo yeserial (server_isn) zvisina kurongeka uye yozoisa nhamba iyoyo mumunda we "Serial number" weTCP header. Tevere, sevha inopinda client_isn + 1 mumunda we "Acknowledgement number" uye inoisa mabhiti ese eSYN neACK ku1. Chekupedzisira, sevha inotumira packet kumutengi, iyo isina data reapplication-layer (uye isina data rekuti sevha itumire). Panguva ino, sevha iri muSYN-RCVD state.
Kana mutengi angogamuchira paketi kubva kuseva, anofanira kuita zvinotevera kuti apindure paketi yekupedzisira yemhinduro: Kutanga, mutengi anoisa ACK bit yemusoro weTCP yepaketi yemhinduro ku1; Chechipiri, mutengi anopinda kukosha server_isn + 1 mumunda we "Simbisa nhamba yemhinduro"; Chekupedzisira, mutengi anotumira paketi kuseva. Paketi iyi inogona kutakura data kubva kuvatengi kuenda kuseva. Kana mabasa aya apera, mutengi achapinda mu ESTABLISHED state.
Kana sevha yangogamuchira reply packet kubva kumutengi, inochinjawo kuenda ku ESTABLISHED state.
Sezvamunoona kubva mumaitiro ari pamusoro apa, kana muchibata maoko nenzira nhatu, kubata maoko kwechitatu kunobvumirwa kutakura data, asi kubata maoko kwekutanga kaviri hakubvumirwi. Uyu mubvunzo unowanzo bvunzwa mubvunzurudzo. Kana kubata maoko nenzira nhatu kwapera, mapato ese anopinda muchimiro cheESTABLISHED, zvichiratidza kuti kubatana kwacho kwabudirira, panguva iyo mutengi neseva vanogona kutanga kutumirana data.
Sei tichikwazisana katatu? Kwete kaviri, kana kana?
Mhinduro inowanzo taurwa ndeyekuti, "Nekuti kubatana maoko kwevanhu vatatu kunovimbisa kugona kugamuchira nekutumira." Mhinduro iyi yakarurama, asi chikonzero chekunze chete, haitauri chikonzero chikuru. Munyaya inotevera, ndichaongorora zvikonzero zvekubatana maoko katatu kubva muzvikamu zvitatu kuti tinzwisise nyaya iyi zvakadzama.
Kubatana maoko kwevanhu vatatu kunogona kudzivirira kutanga kwekubatana kwakadzokororwa kare (chikonzero chikuru)
Kubatana maoko kwevanhu vatatu kunovimbisa kuti mativi ese maviri agamuchira nhamba yekutanga yakavimbika.
Kubatana maoko kwevanhu vatatu kunodzivirira kutambisa zvinhu.
Chikonzero 1: Dzivisa Kubatana Kwekare Kwakadzokororwa
Muchidimbu, chikonzero chikuru chekubatana maoko nenzira nhatu ndechekudzivirira kuvhiringidzika kunokonzerwa nekutanga kwekubatana kwakapetwa kaviri. Munzvimbo yakaoma yenetwork, kutumira mapaketi edata hakugaro tumirwa kune host yekuenda zvinoenderana nenguva yakatarwa, uye mapaketi edata ekare anogona kusvika kune host yekuenda kutanga nekuda kwekuzara kwenetwork nezvimwe zvikonzero. Kuti izvi zvisaitike, TCP inoshandisa kubatana maoko nenzira nhatu kuti isimbise kubatana.
Kana mutengi akatumira mapaketi akawanda ekubatanidza eSYN akatevedzana, mumamiriro ezvinhu akadai sekuzara kwenetwork, zvinotevera zvinogona kuitika:
1- Mapaketi ekare eSYN anosvika paserver asati asvika mapaketi eSYN matsva.
2- Seva ichapindura paketi yeSYN + ACK kumutengi mushure mekugamuchira paketi yekare yeSYN.
3- Kana mutengi agamuchira packet yeSYN + ACK, anoona kuti connection yacho ndeyenhoroondo yekubatana (sequence number expired or timeout) zvichienderana nemamiriro ayo, uye obva atumira RST packet kuserver kuti imise connection yacho.
Nekubatana kwekubata maoko kaviri, hapana nzira yekuziva kana kubatana kuripo kuri kwekare. Kubatana maoko kwemativi matatu kunobvumira mutengi kuona kana kubatana kuripo kuri kwekare zvichienderana nemamiriro ezvinhu kana kwagadzirira kutumira paketi yechitatu:
1- Kana iri nhoroondo yekubatana (nhamba yekutevera yapera kana kuti nguva yapera), paketi inotumirwa nekukwazisana kwechitatu ipaketi yeRST yekudzima nhoroondo yekubatana.
2- Kana isiri nyaya yekubatana kwekare, pakiti inotumirwa kechitatu ipaketi yeACK, uye mapoka maviri ari kutaurirana anobudirira kusimbisa kubatana kwacho.
Saka, chikonzero chikuru chinoita kuti TCP ishandise kubatana kwevatatu ndechekuti inotanga kubatana uku kudzivirira kubatana kwekare.
Chikonzero chechipiri: Kuenzanisa nhamba dzekutanga dzemapato ese ari maviri
Mativi ese ari maviri eTCP protocol anofanira kuchengetedza nhamba yekutevera, inova chinhu chakakosha kuti ive nechokwadi chekuti kutumirwa kwakavimbika. Nhamba dzekutevera dzinoita basa rakakosha mukubatana kweTCP. Dzinoita zvinotevera:
Mugamuchiri anogona kubvisa data rakapetwa kaviri uye kuona kuti data racho rakarurama.
Mugamuchiri anogona kugamuchira mapaketi akatevedzana nenhamba yekutevera kuti ave nechokwadi chekuti data racho rakavimbika.
● Nhamba yekutevera inogona kuziva pakiti yedata yakagamuchirwa nemumwe munhu, zvichiita kuti data ritumirwe nenzira yakavimbika.
Saka, kana TCP yatanga kubatana, mutengi anotumira mapaketi eSYN ane nhamba yekutanga yekutevedzana uye anoda kuti sevha ipindure neACK packet inoratidza kugamuchira zvakanaka packet yeSYN yemutengi. Zvadaro, sevha inotumira packet yeSYN ine nhamba yekutanga yekutevedzana kumutengi uye inomirira kuti mutengi apindure, kamwe chete, kuti ive nechokwadi chekuti nhamba dzekutanga dzekutevedzana dzakabatana zvakavimbika.
Kunyangwe kukwazisana maoko nenzira ina kuchikwanisikawo kuti nhamba dzekutanga dzematanho ese dziri mbiri dzienderane nenzira yakavimbika, danho rechipiri nerechitatu rinogona kubatanidzwa kuita danho rimwe chete, zvichikonzera kukwazisana maoko nenzira nhatu. Zvisinei, kukwazisana maoko uku kunogona kungovimbisa kuti nhamba yekutanga yematanho ese iri muboka rimwe yagamuchirwa zvinobudirira nerimwe bato, asi hapana vimbiso yekuti nhamba yekutanga yematanho ese ari maviri inogona kusimbiswa. Saka, kukwazisana maoko nenzira nhatu ndiyo sarudzo yakanakisa yekutora kuitira kuve nechokwadi chekugadzikana uye kuvimbika kwekubatana kweTCP.
Chikonzero 3: Dzivisa Kuparadza Zvishandiso
Kana paine "kubatana maoko kaviri" chete, kana chikumbiro chemutengi cheSYN chakavharwa munetwork, mutengi haagone kugamuchira paketi yeACK yakatumirwa neseva, saka SYN ichadzoserwa. Zvisinei, sezvo pasina kubatana maoko kwechitatu, sevha haigone kuona kana mutengi akagamuchira ACK achibvuma kuti isimbise kubatana. Saka, sevha inogona chete kutanga kubatana mushure mekugamuchira chikumbiro chega chega cheSYN. Izvi zvinotungamira kune zvinotevera:
Kurasika kwezviwanikwa: Kana chikumbiro cheSYN chemutengi chikavharirwa, zvichikonzera kutumirwa kwemapaketi akawanda eSYN kakawanda, sevha ichagadzira kubatana kwakawanda kusina kushanda mushure mekugamuchira chikumbiro. Izvi zvinotungamira mukurasikirwa kwezviwanikwa zveseva zvisina kufanira.
Kuchengeta mameseji: Nekuda kwekushaikwa kwekubatana kwechitatu, sevha haina nzira yekuziva kana mutengi akagamuchira ACK accredit nemazvo kuti asimbise kubatana. Nekuda kweizvozvo, kana mameseji akamira panetwork, mutengi acharamba achitumira zvikumbiro zveSYN kakawanda, zvichiita kuti sevha igare ichigadzira ma connection matsva. Izvi zvichawedzera kuzara kwenetwork nekunonoka uye zvichakanganisa mashandiro ese enetwork.
Saka, kuti ive nechokwadi chekuti network connection yakagadzikana uye yakavimbika, TCP inoshandisa three-way handshake kusimbisa network kudzivirira kuitika kwematambudziko aya.
Pfupiso
IyoMutengesi weNetwork PacketKugadzwa kwekubatanidza kweTCP kunoitwa nekubata maoko kwemativi matatu. Munguva yekubatirana maoko kwemativi matatu, mutengi anotanga atumira paketi ine mureza weSYN kuseva, zvichiratidza kuti inoda kubatana. Mushure mekugamuchira chikumbiro kubva kumutengi, sevha inopindura paketi ine mureza weSYN neACK kumutengi, zvichiratidza kuti chikumbiro chekubatanidza chagamuchirwa, uye inotumira nhamba yayo yekutanga yekutevedzana. Pakupedzisira, mutengi anopindura nemureza weACK kuseva kuratidza kuti kubatana kwacho kwabudirira. Saka, mapato maviri ari muchimiro cheESTABLISHED uye anogona kutanga kutumirana data.
Kazhinji, nzira yekukwazisana kweTCP yakagadzirirwa kuva nechokwadi chekuti kubatana kwacho kwakasimba uye kwakavimbika, kudzivirira kuvhiringidzika uye kutambisa zviwanikwa nekuda kwekubatana kwekare, uye kuona kuti mapato ese ari maviri anokwanisa kugamuchira nekutumira data.
Nguva yekutumira: Ndira-08-2025
