Internet and Intranet Protocols and Applications

1
Internet and Intranet Protocols and Applications

• Lecture Protocols and Client/Server Applications
• 2/1/0
• Arthur P. Goldberg
• Clinical Associate Professor of Computer Science
  and Information Systems
• New York University
• artg_at_cs.nyu.edu

2
Outline

• Internet Applications
• Numerous client/server Protocols e.g. SMTP (RFC
  821), HTTP, etc.
• Document formats, e.g. Email (RFC 822)
• RFCs
• Standards
• Course administration

3
Important Applications, Infrastructure

• Network Management (SNMP, CMOT, MIB)
• Domain Name System (DNS)
• Graphics and Window Systems ( X windows)
• Time And Date (NTP)

4
Important User Applications Binary

• Telnet
• File Transfer and Access Protocols (FTP, TFTP,
  SFTP, NFS)
• Telephony
• Multimedia (Audio, Video)

5
Important User Applications Text-based

• Mail and Message Systems (SMTP, IMAP, POP3, MIME,
  X.400)
• Network news (NNTP)
• Web (HTTP)
• Real time messaging (IRC)

6
Messages (documents)

• Syntax (RFC 822)
• Headers
• ltblank linegt
• Body
• Semantics
• Protocol specific
• Different Request and Response
• Headers modify meaning

7
Message Syntax

• Body
• representation
• ASCII
• HTML, email, etc.
• Binary
• Encoded in ASCII (MIME, CODE64, etc.)
• Raw (HTTP images)
• End of message
• Close connection
• Termination sequence
• pre-determined (such as .)
• dynamic
• Length
• Blocked

8
Protocol Design Choices

• What semantics?
• What messages?
• Stateful or stateless?
• Which documents(s)?
• Which representation?
• Binary or ASCII?

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Example - Post Office Protocol, Ver. 3, 1996, RFC
1939

• Get mail from server
• TCP
• RFC 822 and MIME
• ASCII
• Stateful

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POP3 MESSAGES

• AUTHORIZATION State
• QUIT
• TRANSACTION State
• STAT
• LIST
• RETR
• DELE
• NOOP
• RSET

• UPDATE State
• QUIT
• Optional POP3
• TOP
• UIDL
• USER
• PASS
• APOP

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RFCs

• Request for Comment
• index ftp//nic.merit.edu/documents/rfc/INDEX.rfc
  
• RFC XXXX ftp//nic.merit.edu/documents/rfc/rfcXXX
  X.txt

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Two Interesting RFCs

• 3 DOCUMENTATION CONVENTIONS, S. Crocker, UCLA,
  1969
• Notes may be produced at any site by anybody and
  included in this series.
• The content of a NWG note may be any thought,
  suggestion, etc. related to the HOST software or
  other aspect of the network. Notes are
  encouraged to be timely . The minimum length
  for a NWG note is one sentence.
• 1700 ASSIGNED NUMBERS, J. Reynolds, J.
  Postel, ISI, 1994

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RFC Characteristics

• RFC Statuses (2026)
• Standard track
• PS - proposed standard
• DS - draft standard
• S - standard
• Non-standards track
• E - experimental
• I - information only
• H - Historic
• BC - Best current practices
• RFC Inter-relationships
• Obsoletes and Obsoleted by

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Administration

• Homework
• Rule whenever you use more than a few words from
  a source, or a few lines of code, attribute the
  source.
• Right way, question 1.8 In message sequences,
  the message boundaries are preserved. When two
  1-KB messages are sent, they arrive as two
  distinct 1-KB messages, never as one 2-KB
  message. Tanenbaum, Computer Networks 3rd
  edition p. 24.
• Style question
• Elementary or advanced?
• Proposal 1 hour each

15
Mnemonics

• "Andrew D. Rosson" ltarosson_at_fpcg.comgt
• President Does Not Talk about Sexual
  Peccadillos Authoritatively
• President Does Not Think Sexual
  Proclivities Amoral
• Li-Miao Chang (Michelle) ltchan9079_at_sparky.cs.nyu.e
  dugt
• Please Do Not Take Sweet Potato Away
• Please Do Not Throw Sausage Pizza Away
• Art Ponders Scene Touches , Naive Dew Pierces.
  
• Jeremy Medows ltmedo9890_at_squeegee.cs.nyu.edugt
• A Pretty Sexy Nurse Danced Provocatively
• A President Stood Naked Declared Paula
• A Person Said Never Do Pot
• Arnold Poindexter Soiled Nice Dark Pants
• Party Down? Never. Says Poindexter Arnold.
• President Did Never Sex Pretty Assistant
• President Dole? Never! Said Populous
  Affirmatively.
• Ling-ju Lin "christina lin" ltchristinaling_at_hotmail
  .comgt
• A person should try new dairy products (every day)