令两个不同的端口号 当客户进程向服务器进程发出建立连接请求时,要寻找连接 服务器进程的熟知端口(21),同时还要告诉服务器进程自己 的另一个端口号码,用于建立数据传送连接。 n服务器进程用自己传送数据的熟知端口(20)与客户进程所提 供的端口号码建立数据传送连接。 由于FTP使用了两个不同的端口号,所以数据连接与控制 连接不会发生混乱。 n使用两个独立的连接的主要好处是: (1)使协议更加简单和更容易实现; (2)在传输文件时还可以利用控制连接
❖ 两个不同的端口号 ◼ 当客户进程向服务器进程发出建立连接请求时，要寻找连接 服务器进程的熟知端口(21)，同时还要告诉服务器进程自己 的另一个端口号码，用于建立数据传送连接。 ◼ 服务器进程用自己传送数据的熟知端口(20)与客户进程所提 供的端口号码建立数据传送连接。 ◼ 由于 FTP 使用了两个不同的端口号，所以数据连接与控制 连接不会发生混乱。 ◼ 使用两个独立的连接的主要好处是： （1）使协议更加简单和更容易实现； （2）在传输文件时还可以利用控制连接
令FTP的工作流程 n登录:客户机向FTP服务器登录,存在两种方式: ◆匿名登录用 anonymous为用户名,以用户自己的电子邮件地 址为囗令 今非匿名登录需要从FTP服务器申请得到用户名和口令。 浏览和下载 退出 FTP FTP file transfer FTP user client server interfa user at host local file remote file system system
❖ FTP的工作流程 ◼ 登录：客户机向FTP服务器登录，存在两种方式： ❖ 匿名登录用anonymous为用户名，以用户自己的电子邮件地 址为口令。 ❖ 非匿名登录需要从FTP服务器申请得到用户名和口令。 ◼ 浏览和下载 ◼ 退出 file transfer FTP server FTP user interface FTP client local file system remote file system user at host
FTP的屏幕信息举例 [ol] ftp nic ddn. mil [04 connected to nic ddn. mil [031 0 nic FTP server (Sunos 4.1)ready [04] ° anonymous [05] est login ok send ident as password 06]p abc@xyz. math. yale. edu [07]23 ogin ok, access restrictions apply [08] ftp 09125n S1100688F11T [01]用户要用FTP和远地主机建立连接。 (128.36.12.27,1401)(4318 bytes) [13] 226 ASCII Transfer complete local: nicinfo remote rfcl261 txt 4488 bytes received in 15 seconds (0. 3 Kbytes/s) [14] ftp> quit 15]221G。。dbye
FTP 的屏幕信息举例 [01] ftp nic.ddn.mil [02] connected to nic.ddn.mil [03] 220 nic FTP server (Sunos 4.1)ready. [04] Name: anonymous [05] 331 Guest login ok, send ident as password. [06] Password: abc@xyz.math.yale.edu [07] 230 Guest login ok, access restrictions apply. [08] ftp> cd rfc [09] 250 CWD command successful. [10] ftp> get rfc1261.txt nicinfo [11] 200 PORT command successful. [12] 150 ASCII data connection for rfc1261.txt (128.36.12.27,1401) (4318 bytes). [13] 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s). [14] ftp> quit [15] 221 Goodbye. [01] 用户要用 FTP 和远地主机建立连接
FTP的屏幕信息举例 [ol] ftp nic ddn. mil [02] connected to nic ddn. mil [03 220 nic FTP server (Sunos 4. 1)ready [043me: anonymous [05] Guest login ok send ident as password [06] rd:abcdxyzmath yale. edu [07]2 login ok, access restrictions apply [08]ft 0aT vA。1AA△eeF11T 02]本地FTP发出的连接成功信息。 [12] 150 ASCII data connection for rfcl261txt (128.36.12.27,1401)(4318 bytes) [13] 226 ASCII Transfer complete local: nicinfo remote rfcl261 txt 4488 bytes received in 15 seconds (0. 3 Kbytes/s) [14] ftp> quit 15]221G。。dbye
FTP 的屏幕信息举例 [01] ftp nic.ddn.mil [02] connected to nic.ddn.mil [03] 220 nic FTP server (Sunos 4.1)ready. [04] Name: anonymous [05] 331 Guest login ok, send ident as password. [06] Password: abc@xyz.math.yale.edu [07] 230 Guest login ok, access restrictions apply. [08] ftp> cd rfc [09] 250 CWD command successful. [10] ftp> get rfc1261.txt nicinfo [11] 200 PORT command successful. [12] 150 ASCII data connection for rfc1261.txt (128.36.12.27,1401) (4318 bytes). [13] 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s). [14] ftp> quit [15] 221 Goodbye. [02] 本地 FTP 发出的连接成功信息
FTP的屏幕信息举例 [ol] ftp nic ddn. mil [02] connected to nic ddn. mil [03] 220 nic FTP server (Sunos 4. 1)ready 0、Name: anonymous [05 1 Guest login ok send ident as password [06] ord: abcl xyz.math. yale. edu [07] login ok, access restrictions apply [08]ft [09]250 successful 「101ftp> xt nicinfo [03]从远地服务器返回的信息,220表示“服务就 (128.36.12.27,1401)(4318 bytes) [13] 226 ASCII Transfer complete local: nicinfo remote rfcl261 txt 4488 bytes received in 15 seconds (0. 3 Kbytes/s) [14] ftp> quit 15]221G。。dbye
FTP 的屏幕信息举例 [01] ftp nic.ddn.mil [02] connected to nic.ddn.mil [03] 220 nic FTP server (Sunos 4.1)ready. [04] Name: anonymous [05] 331 Guest login ok, send ident as password. [06] Password: abc@xyz.math.yale.edu [07] 230 Guest login ok, access restrictions apply. [08] ftp> cd rfc [09] 250 CWD command successful. [10] ftp> get rfc1261.txt nicinfo [11] 200 PORT command successful. [12] 150 ASCII data connection for rfc1261.txt (128.36.12.27,1401) (4318 bytes). [13] 226 ASCII Transfer complete. local: nicinfo remote: rfc1261.txt 4488 bytes received in 15 seconds (0.3 Kbytes/s). [14] ftp> quit [15] 221 Goodbye. [03] 从远地服务器返回的信息，220 表示“服务就 绪