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Telnet and FTP


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  • Traditional virus – damages data by wiping out or altering Worms – First worm was created by Robert Morris on Nov. 2, 1988. He was a grad student at Cornell. According to Morris, it was written to guage the size of the Internet, not to cause damage. Now he is an associate professor at MIT. Trojan Horse comes from a Greek story of the Trojan War where the Greeks offered a gift to their enemies, the Trojans, of a giant wooden horse. After the Trojans drag the horse inside their city, Greek soldiers who were hiding inside the horse, sneak out, open the city gates, and allow their fellow soldiers to capture the city of Troy. Email virus – replicates by mailing itself to email addresses in the victim’s address book Melissa Virus – 3/99 – Microsoft Word documents; would send itself to first 50 people in address book; fastest spreading virus ever; caused shut-down of email I LOVE YOU Virus – 5/4/2000 – Trojan Horse distributed via email. Used Visual Basic for Applications (which could do things like modify files and send email as well as auto-execute which allowed the programmer to insert a program into a doc. That runs automatically when the doc is opened). When the attachment was opened it would activate the virus by sending 50 emails and then infect a central file called NORMAL.DOT so any file saved later was also infected.
  • 6 – make sure that Macro Virus Protection is enabled in all Microsoft applications
  • Free file sharing programs are frequently a major conveyor of adware) Old antivirus software did not scan for adware and spyware because they did not consider them viruses or worms because 1) you give permission to install adware (although you do it unwittingly) and 2) adware does not behave like typical virus or worm since it doesn’t actually do damage other than affecting performance Pop-up blockers to prevent adware and spyware: MSN Toolbar and Google Toolbar To check your computer: use a scanner – software specifically designed for detecting adware and spyware and helping you to remove it E.g., Ad-aware from Lavasoft
  • Transcript

    • 1. Telnet and FTP
    • 2. Telnet
      • Lets you use the resources of some other computer on the Internet to access files, run programs, etc.
      • Creates interactive connection with remote machine
      • To use:
        • Need telnet application software –
          • Microsoft Windows Telnet (built into Windows 95 and greater)
          • Macintosh Terminal (built into Mac OS X and greater)
        • Need an account on remote machine – you will be prompted login and password
        • OR
        • Some systems will allow you to login as guest to access some resources like databases
        • Example:
          • telnet
    • 3. rsh
      • rsh – remote shell
      • Another protocol that allows us login access
      • Use the rlogin (remote login) command in the terminal window
      • Example:
        • rlogin –l username
        • (you can omit –l username if your username is the same on both systems)
      • rlogin skips past the login: prompt and will present the Password: prompt
    • 4. ssh
      • ssh – secure shell
      • ssh is another popular protocol that allows us login access
        • More secure than telnet or rsh since it encrypts all data that passes over the network
        • This can prevent a third party from spying on the network traffic and reading your sensitive information (like your password)
      • Example:
        • slogin –l username
        • (Avoid using the generic with slogin or you may get a warning message about conflicting host keys)
      • ssh secure shell replaces other, insecure terminal applications like Telnet and FTP
    • 5. FTP
      • FTP – file transfer protocol
      • Allows you to send files and directories over a network
      • FTP client – software that allows you to connect to an FTP server on the Internet
        • Originally clients were text-based and used commands (much like UNIX) – these still exist
        • Graphical based FTP clients now exist; e.g.:
          • WS_FTP
          • File Manager through Blackboard
        • Clients transfer data in one of two modes: ascii (for text files) and binary (for all others)
      • Need an account on remote system (username and password) but some sites allow anonymous ftp
        • Login with anonymous
        • Enter email address as password
        • Good for downloading software and database information (otherwise information would have to be sent sneakernet or as an email attachment)
    • 6. Viruses
      • Downloading files from the Internet introduces the possibility that your computer could become infected with a virus
      • Virus – generic term applied to a wide variety of malicious programs that invade your computer; not all cause damage (but many do)
      • Computer virus is similar to biological virus in that it passes from computer to computer like a biological virus passes from person to person
      • Platform specific (e.g., a Windows virus will not infect UNIX system, etc.)
      • Types:
        • Traditional virus – attach to programs or data files, replicate themselves, then damage data, hard disk, etc.
        • Worms – stand alone programs designed to infect networks. They travel from network to network, replicating themselves along the way.
        • Trojan Horse program – legitimate program with hidden code that is activated by a trigger that causes the code to execute
        • Email Virus – gets transmitted in email messages
    • 7. Viruses - Prevention
      • Use a secure operating system
      • Run antivirus software (aka virus detection software)
        • Scanner – checks files to see if they were infected:
          • Looks for characteristic data patterns found in programs infected by known viruses
          • Determines if a program’s file size is changed
        • Eradication program – disinfects by wiping virus from hard drive
        • Innoculators – will prohibit a program from running if it detects a virus
      • Keep antivirus software up-to-date
      • Avoid programs from unknown sources (like Internet) including mail attachments from unknown senders
      • Don’t use pirated copies of software; purchase commercial software on CDs as they cannot be modified
      • Don’t double-click on an email attachment that contains an executable (file extension like .exe, .com, .vbs) and don’t run macros in a document unless you know what they do
      • Back up files regularly just in case…
    • 8. Adware and Spyware
      • Adware – software that displays ads on your computer
        • Ads pop up even if you are not browsing the Web
        • Some companies provide free software in exchange for advertising on your display
      • Spyware – software that sends your personal information to a third party without your permission or knowledge; collects info about:
        • Web sites you visit
        • Sensitive info like your username and password
        • Some companies use collected info to send you unsolicited targeted ads
      • Both cause performance issues with your computer like:
        • Computer hangs frequently, slows down, does not work properly
        • Hijacks your Web browser, gives you a new start page
    • 9. Adware and Spyware - (con’t)
      • Usually install secretly on your computer by either:
        • Tricking you into clicking a link that installs it; e.g., it opens a Window dialog box, you click Cancel and it installs it
        • Installing freeware that installs it; e.g., free file sharing program might secretly install spyware on your computer
      • To protect against adware and spyware:
        • Use antivirus software as newer products now include adware and spyware scanning; Some ISPs are now providing protection from adware and spyware as well
        • Make sure that the programs you install do not contain adware:
          • Read license agreement carefully
          • Check the publisher’s Web site carefully
          • Search the Internet for the name of the program and the keywords adware and spyware
        • Install a pop-up blocker to prevent adware and spyware pop-up windows (then you won’t accidently click a deceptive link)
        • Do not unwittingly install adware or spyware; e.g., you may see a dialog box to verify that you want to install a program – click No