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Basic Services. MIS 4700 Dr. Garrett. How Application Layer IP Protocols Work And Behave. Conventions and behaviors Specifications for the message structures that the protocol or service supports
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Basic Services MIS 4700 Dr. Garrett Guide to TCP/IP, Second Edition
How Application Layer IP Protocols Work And Behave • Conventions and behaviors • Specifications for the message structures that the protocol or service supports • Definition of a well-known port address (or addresses) on which servers listen for service requests • Availability of appropriate software components that implement the various roles that hosts can play in requesting or providing such services
How Application Layer IP Protocols Work And Behave (cont.) • Request/reply messages • Client/server architecture • Peer-to-peer services • Server-to-server traffic • Load balancing • Replication • Pull • Push • Push-pull
Understanding FTP • FTP User Interface (UI) • Protocol Interpreter (PI) • FTP Commands • Data Transfer Process (DTP) • File System
Understanding FTP (cont.) • TCP Transport • TCP-based Command Connection • TCP-based Data Transfer Connection
Understanding Telnet • Bidirectional byte-oriented communication • Terminal Access • Well-known Port 23 server side • Dynamic port number client side
Telnet Elements • NVT • The DO, DON’T, WILL, WON’T Structure • 253 (0xFD) DO • 254 (0xFE) DON’T • 251 (0xFB) WILL • 252 (0xFC) WON’T • Options within the Telnet connection
Understanding SMTP • SMTP elements • Sender-SMTP and Receiver-SMTP • SMTP commands and extensions • SMTP reply codes
Understanding HTTP • Http elements • URIs • Uniform Resource Locator (URL) • Uniform Resource Name (URN) • HTTP methods • Status codes
Other Common IP-based Services • Echo (TCP and UDP) • Quote of the Day (QOD) • Character Generator (Chargen) • Whois • Trivial File Transfer Protocol (TFTP)
Decoding Application Layer Protocols • Decoding TCP/IP Application layer traffic largely depends on two separate but simultaneous forms of analysis • Understanding request/reply messages, recognize related headers and payload information • Assemble multiple lower-layer packets to reconstitute Application layer messages
Other Common IP-based Services (cont.) • Finger • Remote Procedure Call (RPC) • Simple Network Management Protocol (SNMP) • NetBIOS over TCP/IP