QTech QSW-2800 series, Руководство по настройке

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Chapter 44 SSL Configuration
44.1 Introduction to SSL
As the computer networking technology spreads, the security of the network has been taking
more and more important impact on the availability and the usability of the networking
application. The network security has become one of the greatest barriers of modern
networking applications.
To protect sensitive data transferred through Web, Netscape introduced the Secure Socket
Layer
– SSL protocol, for its Web browser. Up till now, SSL 2.0 and 3.0 has been released.
SSL 2.0 is obsolete because of security problems, and it is not supported on the switches of
Network. The SSL protocol uses the public-key encryption, and has become the industry
standard for secure communication on internet for Web browsing. The Web browser integrates
HTTP and SSL to realize secure communication.
SSL is a safety protocol to protect private data transmission on the Internet. SSL protocols are
designed for secure transmission between the client and the server, and authentication both at
the server sides and optional client. SSL protocols must build on reliable transport layer (such
as TCP). SSL protocols are independent for application layer. Some protocols such as HTTP,
FTP, TELNET and so on, can build on SSL protocols transparently. The SSL protocol
negotiates for the encryption algorithm, the encryption key and the server authentication
before data is transmitted. Ever since the negotiation is done, all the data being transferred will
be encrypted.
Via above introduction, the security channel is provided by SSL protocols have below three
characteristics:
Privacy. First they encrypt the suite through negotiation, then all the messages be encrypted.
Affirmation. Though the client authentication of the conversational is optional, but the server is
always authenticated.
Reliability. The message integrality inspect is included in the sending message (use MAC).
44.1.1 Basic Element of SSL
The basic strategy of SSL provides a safety channel for random application data forwarding
between two communication programs. In theory, SSL connect is similar with encrypt TCP
connect. The position of SSL protocol is under application layer and on the TCP. If the
mechanism of the data forwarding in the lower layer is reliable, the data read-in the network
will be forwarded to the other program in sequence, lose packet and re-forwarding will not
appear. A lot of transmission protocols can provide such kind of service in theory, but in actual
application, SSL is almost running on TCP, and not running on UDP and IP directly.