BO CO N TI: FTP PROTOCOL

BO CO N TI: FTP PROTOCOLSinh vin thc hin:L Hu Ti. 1352xxxxNguyn Thnh Vin. 1352xxxxng Phan Xun Hong.13520294Ni dung trnh byTng quan v giao thc FTPM hnh hot ng ca giao thc FTPThit lp iu khin v chng thc ngi dung trong FTPQun l knh d liuCc phng thc truyn trong FTPMt s vn bo mt trong FTP

Tng quan v giao thc FTPFTP(File Tranfer Protocol) l giao thc thng dng trao i tp tin gia 2 my tnh xa dng giao thc TCP/IP.Thng chy trn cng 20 v 21, trn nn ca TCP

Mc ch ca giao thc:Khuyn khch dng chung tp tin (d liu hay chng trnh my tnh)Khuyn khch vic s dng my tnh xa mt cch gin tip Che y s khc bit v h thng lu tr tp tin gia cc my chTruyn ti d liu mt cch tin cy v c hiu qu cao.

Hot ng ca giao thc FTPL ng dng theo m hnh Client Server

Server: chy phn mm cung cp dch v FTP, c nhim v lng nghe nhu cu ca cc my tnh khch trong mng liClient: chy phn mm FTP cho ngi s dng. My khch lin kt vi my ch v c th x l cc thao tc v tp tin nh: ti file ln (xung) my ch, i tn, xa file,.Hot ng ca giao thc FTP

Dng khi to mt phin kt ni FTPD liu s c truyn qua kt ni ny Thit lp iu khin v chng thc ngi dung trong FTPM hnh hot ng ca FTP gm 2 knh d liu v iu khin c thit lp gia FTP client v FTP server. Trc khi kt ni c s dng thc s truyn file, knh iu khin cn phi c thit lp. Mt tin trnh ch nh sau c dng to kt ni v to ra phin FTP lu bn gia cc thit b truyn files.B1: Client s gii mt Username bng lnh USER.Sau Client s password bng lnh PASS n SeverB2: Sever kim tra tn v mt khu ca ngi dng trong Database.Nu hp l,kt ni s c m Qun l knh d liu FTP Dng ch ngPha client s cung cp cc cng cha dng v bt u lng nghe trn cng .Client s dng lnh FTP PORT bo cho server l n ang lng nghe trn port no.Server dng port 20.Server khi to mt kt ni v client.

Qun l knh d liu FTP Dng b ngServer s cp nhng port cha dng v bt u lng nghe trn port .Server s dng lnh FTP PORT bo cho client l port no server ang lng nghe.Pha client s cung cp mt port cha dng.Pha client s khi to mt kt ni d liu n server.Server s xc nhn rng kt ni d liu ny n t client m server gi thng ip trong bc

Cc phng thc truyn d liu trong FTPFTP c ba phng thc truyn d liu, nu ln cch m d liu c truyn t mt thit b ti thit b khc trn mt knh d liu c khi to, l: stream mode, block mode, v compressed mode

Stream ModeD liu c truyn i di dng cc byte khng cu trc lin tip. Thit b gi ch n thun y lung d liu qua kt ni TCP ti pha nhn.Khng c mt trng tiu nht nh c s dng trong phng thc ny lm cho n kh khc so vi nhiu giao thc gi d liu ri rc khc.Phng thc ny ch yu da vo tnh tin cy trong truyn d liu ca TCPBlock modeL phng thc truyn d liu mang tnh quy chun hn, vi vic d liu c chia thnh nhiu khi nh v c ng gi thnh cc FTP blocks. Mi block ny c mt trng header 3 byte bo hiu di, v cha thng tin v cc khi d liu ang c gi.Mt thut ton c bit c s dng kim tra cc d liu c truyn i v pht hin, khi to li i vi mt phin truyn d liu b ngt.Compressed modeL mt phng thc truyn s dng mt k thut nn kh n gin - run-length encoding c tc dng pht hin v x l cc on lp trong d liu c truyn i gim chiu di ca ton b thng ip.Thng tin khi c nn, s c x l nh trong block mode, vi trng header.Mt s vn bo mt FTPPhng php ng nhp n gin ca FTP l mt s k tha ca nhng giao thc thi k u ca Internet. Ngy nay khng cn m bo an ton trn mi trng Internet ton cuChun RFC 2228 v cc phn m rng cho bo mt FTP nh ra thm nhiu ty chn chng thc v m ha phc tp cho nhng ai mun tng thm mc an ton vo trong phn mm FTP ca hCc lnh trong FTP v cc nhm lnhMi lnh c xc nh bi mt on ngn ba ch hay bn ch m lnh, v thc hin mt nhim v c th trong cc chc nng tng th ca FTP. C vi chc cc lnh giao thc, v qun l chng, trong FTP phn loi chng thnh ba nhm, da trn tng th loi chc nng:Access Control Commands: dng ng nhp v xc thc, hoc c s dng truy cp ti nguyn, v iu khin kt ni gia user v serverTransfer Parameter Commands: lnh s xc nh d diu c truyn i nh th no.FTP Service Commands: cha tt c cc lnh thc hin trn tp tin, chng hn nh l gi (nhn) tp tin, xa, i tn tp tin ,.Access Control CommandsCommand codeCommandDescriptionUSERUser NameUser name dng ng nhp vo FTPPASSPasswordMt khu xc thc ca ngi dng sau lnh USERACCTAccountcho php ngi dng chn mt ti khon c nhn no nu nh user c nhiu hn mt ti khon.CWDChange Working DirectoryThay i th mc lm vicCDUPChange To Parent Directory (Change Directory Up)Thay i th mc chaSMNTStructure MountGn kt mt h thng tp tin c thREINReinitializeKhi to li kt niQUITLogoutNgt kt niTransfer Parameter CommandsCommand CodeCommandDescriptionPORTData PortCng m my ch s kt ni nPASVPassiveChuyn sang ch passive modeTYPERepresentation TypeThit lp ch truyn tp tinSTRUFile StructureThit lp cu trc cho cc tp tin (file, record, page)MODETransfer ModeThit lp ch truyn tp tin (Stream, Block or Compressed).Command CodeCommandDescriptionRETRRetrieveYu cu server gi user mt tp tinSTORStoreGi mt tp n serverSTOUStore UniqueGi mt tp tin n server nhng server s kim tra tn tp tin c trn server cha (trnh trng hp ghi )APPEAppend (with Create)nhng nu mt tp tin vi tn c ch nh tn ti, cc d liu c gi c ni vo tp tin tn ti thay v thay th n.ALLOAllocateTo mt khng gian trng nhn mt tp tinRESTRestartKhi ng li mt tp tin chuyn giao ti mt im c nh duRNFRRename Fromi tn t//ni cch khc l tn c ca tp cn c i tnRNTORename Toi tn thnh// ni cch khc l tn mi ca tp tin. RNFR RNTO ABORAbortHy b lnh FTP sau cng v (hoc) hy b chuyn tp tin ang thc hinCommand CodeCommandDescriptionDELEDeleteXa tp tinRMDRemove DirectoryXa th mcMKDMake DirectoryTaoh th mcPWDPrint Working DirectoryTr v cc th mc ang lm vic trn my ch, cho ngi dng bit c h ang u trong h thng tp tin trn serverLISTListTr v thng tin th mc hoc tp tin nu c ch r, ngc li s tr v thng tin ca mc ang lm vic hin tiNLSTName ListGing LIST nhng ch tr v tn cc tp tin trong th mcSITESite ParametersThc hin cc chc nng trn trang web c thSYSTSystemTr v thng tin h iu hnh ca my chSTATStatusTr v trng thi hin tiHELPHelpS tr v cch s dng ca lnh c ch nh, ngc li n s in cc lnh tng qutFTP Reply, Reply Code FormatTi mi thi im User-PI s gi mt lnh n Server-PI qua knh iu khin, server s gi li mt reply. FTP reply server c dng phc v ba mc ch chnh:u tin, xc nhn rng server nhn c mt lnh.Th hai, bo cho cc user divice rng cc lnh c chp nhn hay khng, v nu c li xy ra, n l ci g.Th ba, h truyn cc loi thng tin n ngi dng ca phin hot ng , chng hn nh tnh trng ca qu trnh truyn.

FTP Reply, Reply Code FormatMi m c ba ch s m mi giao tip mt loi hnh c th ca thng tin v tr li phn loi. Mt m c th c coi l hnh thc "xyz", trong "x" l cc ch s u tin, "y" th hai v "z" th ba.

Ch s u tin ca reply code cho bit lnh c gi thnh cng hay tht bi mt cch tng qutCh s th hai c s dng phn loi messenger vo cc nhm chc nngCh s cui cng ca reply code cho bit mt loi hnh c th ca thng ip trong mi nhm chc nng c m t bi ch s th hai y. ch s th ba cho php tng nhm chc nng vi 10 reply code khc nhau cho tng loi reply c a ra bi ch s m u tin xReply Code FormatMeaningDescription1yzPositivePreliminary Replylnh c chp nhn v x l ca n vn ang c tin hnh. User s tip tc ch mt reply khc trc khi c th thm mt lnh mi2yzPositive Completion ReplyLnh c x l thnh cng3yzPositive Intermediate ReplyLnh c chp nhn nhng qu trnh ca n b tr hon trong khi ch nhn thm thng tin. y l dng reply c x dng gia chui lnh4yzTransient Negative Completion Replylnh khng c chp nhn v khng c hnh ng c thc hin, nhng li ny l tm thi v cc lnh c th s c th li mt ln na. iu ny c s dng cho cc li c th l kt qu ca trc trc hoc iu kin c th thay i tm thi5yzPermanent Negative Completion Replylnh khng c chp nhn v khng c hnh ng c thc hin. ang c gng th lnh mt ln na c th s dn n mt li khc.Reply Code FormatMeaningDescriptionx0zSyntaxLi c phpx1zInformationTr li cc yu cu v thng tin, chng hn nh yu cu trng thi.x2zConnectionsTr li lin quan n vic kim sot kt ni hoc kt ni d liu.x3zAuthentication and AccountingTr li lin quan n th tc ng nhp v accountingx4zUnspecifiedKhng xc nh

FTP Reply Code FormatThis diagram shows how the three-digit FTP reply code format is interpreted. In this example, reply code 530, the 5 indicates a permanent error, the 3 specifies that the error is related to authentication or accounting, and the 0 is the specific error type. A similar method is used for reply codes in many other TCP/IP application protocols, including SMTP and HTTP.