8應(yīng)用層E-MAIL

2008–2009文件傳輸協(xié)議FTP簡(jiǎn)單文件傳送協(xié)議引 的FTP服務(wù)器建立連接并登錄后,才RFC959文檔詳細(xì)描述了FTPCUTEFTP,服務(wù)器軟件:SERVER-U,WU-是控制連接，TCP端口為21,主要用于傳輸命令和參數(shù);另一條是數(shù)據(jù)連接,TCP端口為20，主要用于傳送數(shù)據(jù)。文件傳輸協(xié)議FTP簡(jiǎn)單文件傳送協(xié)議FTP 計(jì)算 文件 FTPFTP使用TCP可靠 服務(wù)FTPFTP客戶服務(wù)器方式FTP多個(gè)客戶進(jìn)程提供服務(wù);FTP的服務(wù)器進(jìn)程由兩大部分組主進(jìn)程的工 兩個(gè)連控制連接在整個(gè)會(huì)話期間一直保持打開(kāi)，F(xiàn)TP客實(shí)際用于傳輸文件的是“數(shù)據(jù)連接”。服務(wù)器端的控制進(jìn)程在接收到FTP客戶發(fā)送來(lái)的文件傳輸請(qǐng)求后就創(chuàng)建“數(shù)據(jù)傳送進(jìn)程”和“數(shù)據(jù)連接”，用FTPTCP控制控制用戶控制控制

數(shù)據(jù)

服務(wù)兩個(gè)不同的當(dāng)客戶進(jìn)程向服務(wù)器進(jìn)程發(fā)出建立連接請(qǐng)求時(shí)，要尋找連接服務(wù)器進(jìn)程的端口(21)，同時(shí)還要告訴服務(wù)器進(jìn)程自己的另一個(gè)端碼，用于建立數(shù)據(jù)傳送連接。接著，服務(wù)器進(jìn)程用自己傳送數(shù)據(jù)的熟知端口(20)與客戶進(jìn)程所提供的端碼建立數(shù)據(jù)傳送連接。由于FTP使用了兩個(gè)不同的端，所以數(shù)據(jù)連接與控制連接不會(huì)發(fā)生。在傳輸文件時(shí)還可以利用控制連接來(lái)傳輸命令（例如，F(xiàn)TPftpconnectedto220nicFTPserver(SunosP

e:uestloginok,sendidentas:loginok,accessrestrictions [[[01]用戶要用FTP和 [ NIC上的主機(jī))(7,1401)(4318226ASCIITransferlocal:nicinforemote:4488bytesreceivedin15seconds(0.3ftp>221FTPftpconnectedto220nicFTPserver(Sunos[04]ame:loginok,sendidentas2tloginok,accessrestrictionscand[02]FTP[150ASCIIdataconnectionfor(7,1401)(4318226ASCIITransferlocal:nicinforemote:4488bytesreceivedin15seconds(0.3ftp>221FTPftpconnectedto220nicFTPserver(SunosName:[07]

31Guestloginok,sendidentaspassword.ord:abc@tloginok,accessrestrictions[10]

dxt[1[03]從遠(yuǎn)地服務(wù)器返回的信息，220表示“服務(wù)就緒”[1(7,1401)(4318226ASCIITransferlocal:nicinforemote:4488bytesreceivedin15seconds(0.3ftp>221FTPftpconnectedto220nicFTPserver(SunosName:331Guestloginok,sendidentas[08]

ssword:uestloginok,accessrestrictions[09]200

mand61.txt[04]FTP[表示 local:nicinforemote:4488bytesreceivedin15seconds(0.3ftp>221FTPftpconnectedto220nicFTPserver(SunosName:331Guestloginok,sendidentasPassword:[09]

30Guestloginok,accessrestrictionscdDcommand

rfc1261.txtmandconnectionfor[05]331表示“用戶名正確”local:nicinforemote:4488bytesreceivedin15seconds(0.3ftp>221FTPftpconnectedto220nicFTPserver(SunosName:331Guestloginok,sendidentasPassword:230Guestloginok,accessrestrictions

p>cdCWDcommandrfc1261.txt

mmandconnectionfor1)(4318 guest作 FTPftpconnectedto220nicFTPserver(SunosName:331Guestloginok,sendidentasPassword:230Guestloginok,accessrestrictionsftp>cd250CWDcommand[12]

>getrfc1261.txtORTcommandIIdataconnectionfor27,1401)(4318 ansfer 完畢。3[[15]221FTPftpconnectedto220nicFTPserver(SunosName:331Guestloginok,sendidentasPassword:230Guestloginok,accessrestrictionsftp>cd[09250CWDcommandtp>getrfc1261.txtPORTcommand[12][13]

CIIdataconnectionfor2.27,1401)(4318ansferremote:rfc1261“ftp>”FTP

FTPftpconnectedto220nicFTPserver(SunosName:331Guestloginok,sendidentasPassword:230Guestloginok,accessrestrictionsftp>cd250CWDcommandftp>getrfc1261.txt200PORTcommand[13]

ASCIIdataconnectionfor36.12.27,1401)(4318IITransferinforemote:eceivedin15seconds(0.3[[[09]CWDFTP的標(biāo)準(zhǔn)命令，ChangeWorkingDirectory。[FTP 331

nok,sendidentasestloginok,accessrestrictions>cd250CWDcommandftp>getrfc1261.txt200PORTcommand150ASCIIdataconnectionfor(7,1401)(4318226ASCIITransfercomplete.local:nicinforemote:rfc1261.txt4488bytesreceivedin15seconds(0.3ftp>221FTP[11]PORTFTP建立數(shù)據(jù)連接。200表示“命令正確”Name:331f

ok,sendidentastloginok,accessrestrictionscd0CWDcommandftp>getrfc1261.txt200PORTcommand150ASCIIdataconnectionfor(7,1401)(4318226ASCIITransferlocal:nicinforemote:4488bytesreceivedin15seconds(0.3ftp>221FTP[12]150表示“f

oginok,sendidentasstloginok,accessrestrictionscd CWDcommandftp>getrfc1261.txt200PORTcommand150ASCIIdataconnectionfor(7,1401)(4318226ASCIITransferlocal:nicinforemote:4488bytesreceivedin15seconds(0.3ftp>221FTP[13]226是“釋放數(shù)據(jù)連接”[09]

ginok,sendidentastloginok,accessrestrictionsdWDcommand>getrfc1261.txt00PORTcommand[12150ASCIIdataconnectionfor(7,1401)(4318226ASCIITransfercomplete. local:nicinforemote:rfc1261.txt 4488bytesreceivedin15seconds(0.3Kbytes/s).ftp>221FTPftpconnectedto220nicFTPserver(SunosName:331Guestloginok,sendidentasPassword:230Guestloginokaccessrestrictions[08][09]

c1261.txtcommandIIdataconnectionfor36.12.27,1401)(431826ASCIITransferlocal:nicinforemote:4488bytesreceivedin15seconds(0.3ftp>221FTPftpconnectedto220nicFTPserver(SunosName:331Guestloginok,sendidentasPassword:230Guestloginokaccessrestrictions[08][09]

ftp>200

1261.txtommandIdataconnectionfor 6.12.27,1401)(4318 ASCIITransfercal:nicinforemote:4488bytesreceivedin15seconds(0.3ftp>221NFSNFS可使用戶只 ANFS寫(xiě)數(shù)據(jù)的請(qǐng)求一起發(fā)送到遠(yuǎn)端計(jì)算機(jī)B的NFSNFS文件傳輸協(xié)議FTP簡(jiǎn)單文件傳送協(xié)議(TrivialFileTransferTFTPUDPTFTP沒(méi)有一個(gè)龐大 令集，沒(méi)有列 的功 TFTPPDU512512 PDU文件塊(block)，每個(gè)塊按序編號(hào)，從1開(kāi)始。ASCIITFTP發(fā)完數(shù)據(jù)后在規(guī)定時(shí)間內(nèi)收不到確認(rèn)就要重發(fā)數(shù)據(jù)PDUPDUPDU;這樣就可保證文件的傳送不致因在一開(kāi)始工作時(shí);TFTP客戶進(jìn)程發(fā)送一個(gè)