TCPIP Servers

1
TCP/IP Servers

• LPD (Printing)
• SMTP (Mail)
• FTP (File Transfer)
• NTP (Network Time)
• NNTP (News)
• WEB

2
Network Printing

• Configure the printer hardware on the host system
  by using either the parallel or usb interfaces.
• Add the Windows component Other Network File and
  Printing Services
• uses port 515 (LPD) for BSD Unix printing
• Or get HP JetAdmin software for the system
• uses port 9100 (Jet Direct)
• Or get a network ready printer

3
Printing cont.

• Printer protocols
• Postscript (Adobe)
• is a language executed by the printer
• is very configurable
• PCL (Hewlett Packard)
• is a bit mapped graphics mode
• is faster than postscript
• ASCII (text)
• Plain old printable characters

4
Printer Setup (Network Ready)

• Plug it in to the wall outlet (power)
• Plug in the network cable
• Power up the printer
• Print the configuration sheet
• Register the printer address (preferably
  non-routable)

5
Printing

• PDL (Print Description Languages), basically
  printer drivers.
• Provide a standard interface from the application
  to the printer.

6
Printer maintenance

• Expendable supplies (paper and toner)
• How to fix a paper jam
• Monitor the printer output bin
• Monitor the print quality
• Clean the printer

7
Simple Mail Trasnsfer Protocol

• The protocol is very simple
• Uses port 25
• All files are ascii text
• Syntax user_at_host.domain
• Mail relay userhost1_at_host2.domain
• Mail Exchange (MX)
• Allows mail server redirection

8
SMTP Mail Servers

• POP2, POP3
• Uses port 109 or 110
• Post Office Protocol, mail transfers to client,
  download all mail to the client (older protocol,
  replaced by)
• IMAP
• Uses port 143
• Internet Message Access Protocol, mail stays on
  server
• Better for mobile (transient) clients
• Webmail
• uses a Web interface to access mail

9
Mail Clients

• Eudora
• Commercial
• Netscape Messenger
• Comes with Netscape
• Outlook
• Comes with Windows 9x, 2000
• Webmail, Groupwise
• Uses any web browser

10
Client Setup

• Client can have separate mail server and smtp
  server.
• Mail server is where our mail is received
• SMTP server is where we send our messages
• The Mail server can have virus and spam filters

11
Spamming

• Mail Relaying to an off site recipient
• Testing SMTP mail
• abuse.net
• Configuration to prevent SPAM
• allow only local domain relays to internet

12
Headers

• From
• Date
• Subject
• To
• Resent-date
• Resent-from

13
Attachments

• Using mail to transfer files
• Simple operation
• Incompatible programs
• Word for MAC vs. Word for PC
• .pdf solves the compatibility problem
• Dangers (viruses, trojan horses)
• Executable programs that the client downloads and
  automatically executes

14
Encoding Methods

• Binary Files (programs, sound, video)
• UUENCODE (UNIX)
• one file per encode
• MIME (WWW, POP, IMAP)
• multiple files per encode
• BinHex (Apple)
• one file per encode

15
SMTP Example
1gt telnet cc.usu.edu.edu 25 2gt 220
grumpy.usu.edu ESMTP Server (PMDF V5.2-32) 1gt
HELO pc15.logan.tv 2gt 250 grumpy.usu.edu Ok,
port 32443_at_techsun.cs.usu.edu
129.123.7.33 1gt MAIL Fromltstudent11_at_pc15.log
an.comgt 2gt 250 2.5.0 Address Ok. 1gt RCPT
Toltmailman_at_red.rutgers.edugt 2gt 250 2.1.5
bobw_at_cc.usu.edu Ok. 1gt DATA 2gt 354 Start Mail
input end with ltCRLFgt.ltCRLFgt 1gt Date Sat, 22
Mar 1998 132631 MST 1gt From
student11_at_pc15.logan.com 1gtSubject Meeting
tomorrow
16
SMTP Example cont.
1gt The meeting is TOMORROW at 300
PM! 1gt 1gt . 2gt 250 2.5.0 Ok 1gt QUIT 2gt 221
2.3.0 Bye received. Goodbye.
17
FTP

• File Transfer Protocol
• User
• Anonymous
• GET/PUT/DEL/CWD
• GUI Interface
• Binary/Ascii
• Hash

18
FTP Example

• requires 2 ports
• telnet ftp.remotesite.com 21
• 220 ftp.remotesite.com FTP server ready
• user anonymous
• 331 password required for anonymous
• password user_at_cc.usu.edu
• 230 user anonymous logged in
• PORT 1200

19
FTP Example cont.

• PORT 129,123,7,55,4,76
• 200 PORT command successful
• pwd
• 257 /export/guest/bobw is current directory
• RETR ./.login
• 150 ASCII data connection for ./.login(129.123.7.5
  5,1100)(795 bytes)
• QUIT

20
NTP

• Network Time Protocol
• Uses port 123
• UDP (User Datagram Protocol)
• Atomic Clock Synchronization
• Multiple Servers
• Used for
• Distributed Databases
• Client/Server
• Security

21
Clock Synchronization
mt
mr
Time Server
Time Client
Tround mt mr time t Clock set is t
Tround/2
22
NNTP

• Network News Transfer Protocol
• Uses port 119
• Distributed Bulletin Board
• Uses a tree hierarchy
• Minimizes Duplicate messages/disk space
• Tree based distribution
• Store and Forward

23
Web Browsers

• Mosaic
• More or less the first web browser
• Netscape
• Became extremely popular very quickly
• Microsoft Internet Explorer
• Plays catch up with Netscape
• HotJava
• Sun Microsystems Browser

24
Web Browsers Cont.

• Web Browsers can cache pages and pictures locally
  to speed up access
• Web Browsers can use a proxy server to remotely
  cache pages and pictures for many systems.
• The proxy can act as a firewall and IP translator.

25
Web Servers

• Apache
• Roxen
• Netscape
• Microsoft
• IIS

26
Web Servers Cont.

• Use http (hyper text transfer protocol) to create
  file and service access
• Can have virtual servers to save IP addresses
• Can have additional ports (services)
• Most of the fancy stuff is done by the browser.

27
HTML

• Hyper Text Markup Language
• Uses ascii text and commands
• Automatically formats text
• Sets up hyper links and displays pictures
• Connects to services such as ftp
• Start with ltcommandgt and end with lt/commandgt

28
HTML Cont.

• ltBODYgt
• lta hrefhttp//www.usu.edugtlt/agt
• lta imagefred.gifgtlt/agt
• ltligtHellolt/ligt
• lt/BODYgt

29
XML

• eXtensible Markup Language
• Extends basic HTML to aid in creating documents
  and document systems.
• Creates access to data bases

30
CGIs Common Gateway Interface

• Allow Web browsers to execute programs on the Web
  server.
• Uses Mail, finger, database, animation, sound
• Found in /cgi directory in the Web page home
• Are executable C, perl, java, or shell programs

31
ASP

• Active Server Pages
• Similar functions to CGIs
• Can do access counters, database access and
  online forms (fill in the blank)

32
PHP

• Personal Home Page Tools
• Language for creating Web programs
• Syntax is similar to Basic

33
Java

• Developed by Sun
• C context
• Builds GUIs (Graphical User Interfaces)
• Handles animated objects on the web page

34
Security and the WEB

• WEB files must be world readable.
• The WEB server may be run by root
• CGIs can be dangerous security holes.
• PHP, ASP, and VBscripts can have security holes
  (buffer overflows)
• WEB servers are searched by many search engines
  that broadcast your data.