文件傳輸服務(wù)FTP(中山大學(xué)計(jì)算機(jī)網(wǎng)絡(luò)實(shí)驗(yàn)資料)

1、 FTP服務(wù)的工作過程服務(wù)的工作過程 TCP通信過程 TCP數(shù)據(jù)報(bào)格式 正常TCP通信過程: 建立連接 數(shù)據(jù)傳輸 斷開連接TCP數(shù)據(jù)報(bào)格式TCP數(shù)據(jù)報(bào)格式 TCP標(biāo)志位 ACK：確認(rèn)標(biāo)志 RST： 復(fù)位標(biāo)志 URG：緊急標(biāo)志 SYN：建立連接標(biāo)志 PSH： 推標(biāo)志 FIN： 結(jié)束標(biāo)志TCP連接建立過程TCP數(shù)據(jù)傳輸過程TCP PacketEstablishedEstablishedSEQ=1001,ACK=751,dataLen=256Sending1Waiting1SEQ=751,ACK=1257OK1ACK1SEQ=751,ACK=1513OK2ACK2SEQ=1257,ACK=751,d

2、ataLen=256Sending2Waiting2TCP連接斷開過程TCP PacketEstablishedEstablishedSEQ=1513,ACK=751,CTL=FIN|ACKFIN-WAIT-1CLOSE-WAITSEQ=751,ACK=1514,CTL=ACKFIN-WAIT-2CLOSE-WAITSEQ=751,ACK=1514,CTL=FIN|ACKTIME-WAITLAST-ACKSEQ=1514,ACK=752,CTL=ACKTIME-WAITCLOSEDCLOSED實(shí)驗(yàn)環(huán)境 位于同一局域網(wǎng)內(nèi)的兩臺主機(jī)，IP分別為：4，19

3、 一個(gè)C/S模式的程序，實(shí)現(xiàn)簡單的TCP數(shù)據(jù)發(fā)送與接收 Client運(yùn)行在4 Server運(yùn)行在19實(shí)驗(yàn)環(huán)境 Client發(fā)送兩次數(shù)據(jù)，內(nèi)容分別為123和456，然后發(fā)送0結(jié)束TCP連接。 程序截圖如下?？蛻舳税l(fā)送數(shù)據(jù)客戶端發(fā)送數(shù)據(jù)服務(wù)端接收到數(shù)據(jù)服務(wù)端接收到數(shù)據(jù)捕獲數(shù)據(jù)包 在Client發(fā)送數(shù)據(jù)之前，在4主機(jī)(Client)上開啟Ethereal。 在捕獲前不進(jìn)行過濾，直接捕獲所有數(shù)據(jù)包。 當(dāng)Client結(jié)束TCP連接之后，停止捕獲數(shù)據(jù)包。 采用捕獲后過濾的方法，過濾規(guī)則是tcp AND ip.addr=

4、19其中，19是Server主機(jī)。 過濾后，共得到11個(gè)數(shù)據(jù)包，見下頁圖。數(shù)據(jù)包詳細(xì)分析 這11個(gè)數(shù)據(jù)包的含義如下： 13：三次握手，建立連接 45：第一次發(fā)送數(shù)據(jù) 67：第二次發(fā)送數(shù)據(jù) 811：斷開連接 下面將對這11個(gè)數(shù)據(jù)包進(jìn)行詳細(xì)分析。1 CS SYNSEQ=X+0與與TCP報(bào)報(bào)文文格格式式相相對對應(yīng)應(yīng)2 SC SYN,ACKSEQ=Y+0ACK=X+13 CS ACKSEQ=X+1ACK=Y+1三次握手結(jié)束三次握手結(jié)束4 CS PSH,ACKSEQ=X+1, data length=256, next seq=257ACK=Y+1數(shù)據(jù)內(nèi)容見下頁圖數(shù)據(jù)內(nèi)容見下頁圖T

5、CP segment data(256 bytes)這是第一次這是第一次發(fā)送的數(shù)據(jù)發(fā)送的數(shù)據(jù)1235 SC ACKSEQ=Y+1ACK=X+257第一次傳輸數(shù)據(jù)結(jié)束第一次傳輸數(shù)據(jù)結(jié)束6 CS PSH,ACKSEQ=X+257, data length=256, next seq=513ACK=Y+1數(shù)據(jù)內(nèi)容見下頁圖數(shù)據(jù)內(nèi)容見下頁圖TCP segment data(256 bytes)這是第二次這是第二次發(fā)送的數(shù)據(jù)發(fā)送的數(shù)據(jù)4567 SC ACKSEQ=Y+1ACK=X+513第二次傳輸數(shù)據(jù)結(jié)束第二次傳輸數(shù)據(jù)結(jié)束8 CS FIN,ACKSEQ=X+513ACK=Y+19 SC ACKSEQ=Y+

6、1ACK=X+51410 SC FIN,ACKSEQ=Y+1ACK=X+51411 CS ACKSEQ=X+514ACK=Y+2TCP連接已經(jīng)斷開連接已經(jīng)斷開 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restricti

7、ons apply.08 ftp cd rfc09 250 CWD command successful.10 ftp get rfc1261.txt nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kb

8、ytes/s).14 ftp quit15 221 Goodbye.01 用戶要用 FTP 和遠(yuǎn)地主機(jī)建立連接。 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc

9、09 250 CWD command successful.10 ftp get rfc1261.txt nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 2

10、21 Goodbye.02 本地 FTP 發(fā)出的連接成功信息。 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command succes

11、sful.10 ftp get rfc1261.txt nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.03 從遠(yuǎn)地服務(wù)器返回的信息

12、，220 表示“服務(wù)就緒”。 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command successful.10 ftp get r

13、fc1261.txt nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.04 本地 FTP 提示用戶鍵入名字。用戶鍵入的名字表示“匿名

14、”。用戶只需鍵入 anonymous 即可。 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command successful.10 f

15、tp get rfc1261.txt nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.05 數(shù)字 331 表示“用戶名正確”，需要口

16、令。 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command successful.10 ftp get rfc1261.txt n

17、icinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.06 本地 FTP 提示用戶鍵入口令。用戶這時(shí)可鍵入guest 作為匿名的口令，也可以

18、鍵入自己的電子郵件地址，即名為 xyz 的主機(jī)上的 abc。 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command success

19、ful.10 ftp get rfc1261.txt nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.07 數(shù)字 230 表示用戶已

20、經(jīng)注冊完畢。 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command successful.10 ftp get rfc1261.t

21、xt nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.“ftp”是 FTP 的提示信息。用戶鍵入的是將目錄改變?yōu)榘?RFC 文件的

22、目錄。 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command successful.10 ftp get rfc1261.txt

23、nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.09 字符 CWD 是 FTP 的標(biāo)準(zhǔn)命令，代表 Change Working Di

24、rectory。 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command successful.10 ftp get rfc1261

25、.txt nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.10 用戶要求將名為 rfc1261.txt 的文件復(fù)制到本地主機(jī)上，并改

26、名為 nicinfo。 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command successful.10 ftp get rfc1

27、261.txt nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.11 字符 PORT 是 FTP 的標(biāo)準(zhǔn)命令，表示要建立數(shù)據(jù)連接。2

28、00 表示“命令正確”。 01 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command successful.10 ftp get rfc

29、1261.txt nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.12 數(shù)字 150 表示“文件狀態(tài)正確， 即將建立數(shù)據(jù)連接”。 0

30、1 ftp 02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command successful.10 ftp get rfc1261.txt nicin

31、fo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.13 數(shù)字 226 是“釋放數(shù)據(jù)連接”?，F(xiàn)在一個(gè)新的本地文件已產(chǎn)生。 01 ftp nic.d

32、02 connected to 03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command successful.10 ftp get rfc1261.txt nicinfo11 200 PO

33、RT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 bytes).13 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s).14 ftp quit15 221 Goodbye.14 用戶鍵入退出命令。 01 ftp 02 connected to

34、03 220 nic FTP server (Sunos 4.1)ready.04 Name: anonymous05 331 Guest login ok, send ident as password.06 Password: 07 230 Guest login ok, access restrictions apply.08 ftp cd rfc09 250 CWD command successful.10 ftp get rfc1261.txt nicinfo11 200 PORT command successful.12 150 ASCII data connection for rfc1261.txt (7,1401) (4318 b