CS4550 Computer Networks II APPLICATIONS TELNET Feit Chap 13 FTP Feit Chap 14 EMail Feit Chap 16

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CS4550 Computer Networks IIAPPLICATIONSTELNET
Feit Chap 13FTP Feit Chap 14E-Mail
Feit Chap 16

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TELNET
PURPOSE Provide alphanumeric terminal
communication between two computers INSTALLATION
Typically available as part of network SW in
W95, NT, unix NETWORK SERVICES connection TCP
well known port 23 run from command prompt
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TELNET ARCHITECTURE
Application
NVT
Telnet Client
Telnet SERVER
Port 23
TCP
TCP Connection
TCP
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Network Virtual Terminal (NVT)
Data Format 8th bit 0 ASCII 0 -127 Control
Data 8th bit 1 ASCII 128-255 OPTIONS
NEGOTIATION (DO,WILL), (DO,WONT), (WILL,DO),
(WILL,DONT) Option Codes see Feit Table
13.3 Internet Assigned Numbers
Authority,www.iana.org Format IAC
request byte option code Example255 250 24
Means Will terminal type
24
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TELNET SESSION
Command Format telnet hostname
port Connecting to other ports example telnet
cs.nps.navy.mil 25 220 cs.nps.navy.mil ESMTP
Sendmail 8.9.2/8.9.2 Tue, 1 Feb 2000 091809
-0800 PST) HELO wolf 250 cs.nps.navy.mil Hello
wolf.cs.nps.navy.mil 131.120.8.161, pleased to
meet you quit 221 cs.nps.navy.mil closing
connection