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Published byKaitlin Foat Modified over 10 years ago
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TCP/IP Suit by Behrouz Fourozan 4 th Ed
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General purpose client server program Developed when time sharing systems were being used Time sharing environment Large computer with multiple users Interaction with user through terminals Login Local login Remote login Internet Computing (CS-413) 2
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Data characters 8b long MSB =0 Control characters 8b long MSB=1 Examples EOF, EOR, SE, NOP, DM, IP, AO, GA, will, do, dont, IAC Internet Computing (CS-413) 4
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Uses TCP port 23 for server Client may use any port Same connection for data and control Control character is preceded by Interpret as Control (IAC) Eg cat file1 mistyped to cat filea 1 catfileaIACEC1 Internet Computing (CS-413) 5
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telnet lets client and server negotiate option before or during the use of the service Options are extra features available to a user with more sophisticated terminal Examples binary, ECHO, Suppress go ahead, status, timing marks, terminal type, terminal speed, line mode Internet Computing (CS-413) 6
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To use options, option negotiation is required Four control characters WILL WONT DO DONT Enabling an option Some can be enabled only by server, some only by client and some by both Two possibilities Offer or request Internet Computing (CS-413) 7
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disabling Two possibilities Offer to disable Request to disable Symmetry Client and servers are given equal opportunity If one party wants an option enabled, it may offer or request Internet Computing (CS-413) 8
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Some options require additional information Example define type or speed of a terminal SE – suboption end SB – suboption begin Internet Computing (CS-413) 9
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Client may be controlled by ctrl+C or back space etc Server is controlled through special characters IP – interrupt process AO- Abort output AYT – are you there EC- erase last character EL- erase line Internet Computing (CS-413) 10
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Control characters are preceeded by IAC and sent out of order TCP segment is marked with URG bit and Urgent data pointer Urgent data points to DM (data mark) character. DM tells where the out of order data is present Internet Computing (CS-413) 11
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