Basic Internet Services , login, file transfer, news, document distribution, Web services Service management

2 Active message delivery – “push” technology TCP Port: 25 uses Simple Mail Transfer Protocol (SMTP) Clients: mailx, pegasus, MS Outlook, Netscape Messenger, Mozilla Thunderbird… Servers: Sendmail (Unix), MS-Exchange, Netscape Messaging Server, Mailman, Maiser…

3 Terminal Emulation uses Telnet protocol TCP Port: 23 Clients: telnet Servers: telnetd (Unix) Now rarely used (for security reasons)

4 Secure Terminal Emulation Secure Shell protocol (ssh) Uses TCP port 22 Handles session key negotiation and encryption of traffic Also possible to do encapsulation of data from other ports on client and server machines (port forwarding) Client: ssh, putty, teraterm Server: sshd (unix)

5 File Transfer Uses File Transfer Protocol (FTP) Port: 21 Clients: ftp Servers: ftpd (Unix), embedded in IIS (Win32)

6 Secure File Transfer Secure File Copy (scp) Secure File Transfer Protocol (sFTP) Usually implemented as cp or ftp inside ssh encapsulated session Clients: winSCP (win32), Fugu (Mac OS/X) Servers: sshd (UNIX)

7 News Passive messaging - “pull technology” Uses Network News Transfer Protocol Port: 119 Clients: MS Outlook, Netscape Collabra, Mozilla Thunderbird Servers: nntpd(Unix),

8 Web Services Uses HTML for message format and HTTP for message transport port: 80 (or 8080) or 445 for secure HTTP Clients: Mozilla firefox, Netscape Navigator, MS InternetExplorer, Opera Servers: IIS (win32), apache (unix & win32), tinyhttpd

Client/Server, 1-to-Many With each of the preceding, multiple clients may communicate with a single server

10 File Transfer Protocol (FTP)

11 The normal usage of this application is to create a message for another user on a local or remote computer system and have it delivered electronically. An example of “push” delivery

12 e.g. mail Subject: How is the Project? Message Hi, I got your last message etc (cont’d)

13 (cont’d) The message is sent from the originating mail serving application to the destination mail serving application via a route that may pass through many mailservers on its way. MTA mailservers Mail clients

14 Received: from (2) ALPHA8.MONASH.EDU.AU by (1) silas.monash.edu.au (8.9.3/ /16Feb AM) id XAA ; Tue, 23 Apr :50: (EST) Received: from blammo.monash.edu.au ([ ]) by (3) vaxh.monash.edu.au (PMDF V #39306) with ESMTP id for Tue, 23 Apr :50: Received: from blammo (unknown [ ]) by (4) localhost (Postfix) with ESMTP id C002 for ; Tue, 23 Apr :50: (/etc/localtime) Received: from mail1.monash.edu.au (bigted.monash.edu.au [ ]) by (5) blammo.monash.edu.au (Postfix) with ESMTP id 14A8512C002 for ; Tue, 23 Apr :50: (EST) Received: from ALPHA1.MONASH.EDU.AU ([ ]) by (6) mail1.monash.edu.au (Netscape Messaging Server 4.15) with ESMTP id GV0X4I00.NBA for ; Tue, 23 Apr :50: SMTP Headers

15 Received: from (8) blammo.monash.edu.au ([ ]) by (7) vaxc.monash.edu.au (PMDF V6.1 #39306) with ESMTP id for (ORCPT Tue, 23 Apr :50: Received: from blammo (unknown [ ]) by localhost (Postfix) with ESMTP id 762F512C002 for ; Tue, 23 Apr :50: (/etc/localtime) Received: from (9) mail021.syd.optusnet.com.au (mail021.syd.optusnet.com.au [ ]) by blammo.monash.edu.au (Postfix) with ESMTP id 1F4AE12C002 for ; Tue, 23 Apr :50: (EST) Received: from CO A (10) (c16494.frank1.vic.optusnet.com.au [ ]) -- SMTP Headers

16 by mail021.syd.optusnet.com.au (8.11.1/8.11.1) with SMTP id g3NDoRi15920 for ; Tue, 23 Apr :50: Date: Tue, 23 Apr :51: From: Patrik Subject: Questions To: Message-id: MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V X-Mailer: Microsoft Outlook IMO, Build ( ) Content-type: MULTIPART/MIXED; BOUNDARY="Boundary_(ID_DI+xGCWXZlChun9D5NMJlw)" Importance: Normal X-Priority: 3 (Normal) X-MSMail-priority: Normal Parts/Attachments: -- SMTP Headers

17 – the SMTP Model User Agent Local MTA Processing Queue MTA RelayLocal MTA Mailboxes User Agent

18 The SMTP Model MTA: A mail transfer agent exchanges mail over a TCP/IP connection System administrator is responsible for setting up the MTA SMTP defines a MTA that implements a system based upon the spooling of messages.

19 SMTP First proposed in RFC821 Later updated in RFC822 – replaced X.400 Commands HELO client identifies itself MAIL/RCPT identifies originator and recipient DATA for sending the contents of the mail QUIT terminates the mail exchange RSET aborts a transfer and resets both the ends VRFY to verify the address without actually sending NOOP forces server to respond with OK EXPN expands a mailing list TURN lets client and server switch roles

20 Mailing Lists To send mail to a group of users, mailing lists are often used. A mail server is needed to distribute the mail messages to members of a mailing list. List can be manually created, or may be automatically maintained.

21 Mailing Lists Listservers maintaining automated lists receive mail messages from new list members requesting that they be added to the list. eg. subscribe FIT2018_Notices Self registration method…

22 Mailing Lists List members can also remove themselves from the list. eg. unsubscribe FIT2018_Notices Messages will be sent to all members of the list when is posted to the listname address on the computer that is hosting the list. eg.

23 Terminal Connectivity Allows remote users to log into computers that are attached to the network. Users can be located anywhere that there is a network connection. As if they were sitting at a terminal that was physically attached to that computer. Security implications: the conversation may not be private if using an internet connection

24 Terminal Connectivity (cont’d) eg. terminal session accessing the library computer library.monash.edu.au (before 2000… now uses web interface)

25 COMPUTER A FTP Server COMPUTER B FTP Client Assign1.doc File Transfer Protocol (FTP) Moving files from one computer To another over the Internet GET PUT

26 FTP -- Anonymous ftp To use ftp, a user normally must identify themselves with a username and password. Having accounts for all possible users is impractical. An anonymous user account is maintained on many ftp servers

27 FTP -- Anonymous ftp The anonymous account is restricted to certain areas of the server and will normally have restricted privileges (e.g. may only be permitted to read and not write). Most systems require the user's address to be typed instead of a password. Many ftp servers use the account ftp (its easier to type). Most WWW browsers support ftp as a built in function making it easy to use file transfer

28 News All network of news servers around the Internet implements the Network News Transfer Protocol (NNTP). These systems support a special-interest group type of information service. Servers use peer-to-peer transfer (news feed)

29 News Messages can be posted to a news group and will then be copied to all news servers over a period of time.

30 News messages can be read by anyone using a news client that is attached to a news server. Most WWW browsers and readers have NNTP plug-in applications News

31 HyperText Transfer Protocol (HTTP) HyperText Markup Language a simple markup language used to create hypertext documents that are portable from one platform to another HTML documents are SGML documents ISO Standard 8879:1986 Information Processing Text and Office Systems; Standard Generalized Markup Language (SGML)

32 HTTP (cont’d) HTML describes the structure and organization of a document It only suggests appropriate presentations of the document when processed Tags define the start and end of headings, paragraphs, lists, character highlighting and links

33 CPE2009 Lectures etc… HTTP (cont’d)

34 HTTP (cont’d)

35 HTTPD Administration Ref: Virtual directory structure Directory Indexing Security –Access control and user authentication –Secure server –chroot server –Kereberos, MD5 authentications Imagemaps CGI (Common Gateway Interface) Configurations Virtual Hosting Logfile rotations Starting, stopping, and restarting the daemon Multiple DirectoryIndex KeepAlive Redirect Directives Server-side includes

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