1. 1 CS4550 Computer Networks II Topics In Applications Ref: Feit Chap 13-20 Tanenbaum Chap 7

2. Clients, requestor programs Servers, demon, reply peer Telnet FTP SNMP E-mail WWW Telnet FTP SNMP E-mail WWW TCP UDP IP DL and physical TCP UDP IP DL and physical From Port 23 From Protocol 6 To port 23 To protocol 6 General Architecture

3. Common Tools PingEcho 7/udp netstattime 13/udp traceroute tracertquote 17/udp

4. TELNET First Application Connect as a terminal to a networked host Terminal emulation Telnet to selected port Commands

5. Connect as a terminal to a networked host NVT - Network Virtual Terminal Solves Multi vendor problem NVT code - 7 bit USASCII 128 characters Line Format- half duplex, stop and wait, Command Format - Interpret As Command (IAC) Escape character IAC = 255 note 8’th bit set IACCommandoption 25525124 willterminal type

6. Terminal emulation

7. Telnet cs.nps.navy.mil 7 echo service telnet cs.nps.navy.mil 13 time of day service telnet cs.nps.navy.mil 80 www service telnet cs.nps.navy.mil 25mail service type help Connect to a selected port

8. Telnet Commands get a list of commands Wolf> telnet telnet > ?