Internet Web Internet Internet TCPIP ISP DNS ClientServer
Internet相关技术 分组交换 Web应用 Internet应用 网络协议 Internet TCP/IP ISP DNS Client/Server
DNS-命名空间 通用 国家 com edu gov int net org mil us cn fr jp hk Sun edu ac com bj sh gd www pku cs lib sess irsgis www 每个域按照从“树叶”到“数根”的次序命名，中间以点隔开。
DNS-提供的服务 n 域名到IP地址的转换 n 主机别名(Host aliasing) n 邮件服务器别名(Mail Server aliasing) n 负载分配(Load distribution)
电子邮件-SMTP定义了14个命令，它们是： HELO <SP> <domain> <CRLF> MAIL <SP> FROM: <reverse-path> <CRLF> RCPT <SP> TO: <forward-path> <CRLF> DATA <CRLF> RSET <CRLF> SEND <SP> FROM: <reverse-path> <CRLF> SOML <SP> FROM: <reverse-path> <CRLF> SAML <SP> FROM: <reverse-path> <CRLF> VRFY <SP> <string> <CRLF> EXPN <SP> <string> <CRLF> HELP [<SP> <string>] <CRLF> NOOP <CRLF> QUIT <CRLF> TURN <CRLF>
电子邮件-SMTP telnet sunrise. pku. edu. cn 25 S: HELO pku. edu. cn R: 250 Hello pku. edu. cn, pleased to meet you S: MAIL FROM: <zy@pku. edu. cn> R: 250 OK S: RCPT TO: <mr. zy@263. net> R: 250 OK S: RCPT TO: <zy@263. net> R: 550 No such user here S: DATA R: 354 Start mail input; end with <CRLF> S: Hello S: this is a test S: <CRLF> R: 250 OK S: QUIT R: 221 263. net closing connection
电子邮件-邮件格式 1. From: user 1@domain 1. com 2. To: user 2@domain 2. com 3. Subject: Explaination of mail format 信件信头(message header) 4. Date: Thu, 1 Apr 1999. 10: 00 GMT 5. Hi, Jack 7. This mail is to explain you the mail format 信体(message body) 8. - - - 9. Thanks 10. Bob
VPN技术 n n n V－－Virtual－－Tunnel－－ PPTP (software) L 2 TP (hardware) IPSec (hardware) P－－Private－－Secure－－ Privacy Integrity Authenticity N－－Network－－Internet Intranet Extranet
VPN主要的4项技术 n 穿隧技術(Tunneling)； q n 加解密技術(Encryption & Decryption) q n Symmetric、Asymmetric cryptography 密鑰管理技術(Key management) q n PPTP、L 2 TP、IPSec SKIP、IKE 使用者與設備身份認證技術(Authentication) q PAP、CHAP、X. 509
- Slides: 26
