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Linux:Log in

To log on to Linux, you need two things, your username and your password given to you in week 1. Both of these are individual to you and give you lone access to your account. Your log in screen should look like the following

You type your username in the space given. You are then asked for your password. If these are valid, you will be logged in to your Linux account. When you type your password, each character appears as an asterisk. During orientation week you were given information on using Microsoft Windows 2000. The password that was given to you in orientation week is a valid password for ITD computers in any building in the university except the computer building. The CSIS department has given you a password that is valid for Windows 2000 and Linux in the computer building.The Microsoft Windows NT login screen looks like this:

If you need to use Linux, and a computer is displaying the Windows login screen as shown above, you will need to restart the computer. To reboot a computer from Windows to Linux, do the following:

Press CTRL-ALT-DEL (control, alt and delete keys at the same time)
Choose Shut-Down
Choose shut-down and Restart
The computer will restart
While restarting you will be offered a list of operating systems Windows 2000 Redhat Linux 7.3
Use the cursor control keys to pick Redhat Linux

Username

Your username is of the format:

cid_number for Computer Systems students eg c001423
mid_number for Mathematics and Computing students eg m0019856
fid_number for Computing with French eg f001234

Password

First of all, you need to be able to remember it. Being able to type it is also nice, though less important than being able to remember it. Second, it must not be easily guessable. A password that is related to your login name or your real name in an obvious way can be easily guessed and therefore is not a "Good Password". Third, it needs to be a reasonably large number of characters. Three letter passwords can be easily guessed by an obvious "brute force" method -- just try them all. A "Good Password" has 7 or 8 characters in it. (Note: longer passwords are even better, but the password checking routines on many Unix systems silently discard any characters after the eighth one.) Fourth, it needs to have more than just letters in it. You should include letters (upper- and lower-case), digits, and punctuation marks. Control characters are nice in theory, but some Macintosh and PC software doesn't like these, so you should probably avoid control characters if you work in an environment with Macs or PCs. Fifth, it should not contain any sequences of 4 or more letters (regardless of how you capitalize them), that can be found in a dictionary. Also, reversing the order of the letters doesn't do any good either. A standard way of cracking a password is to try all the words in a dictionary, in all possible upper-/lower-case combinations, both forward and backward. Prepending and/or appending a digit or punctuation character to a dictionary word doesn't help either; on a modern computer, it doesn't take too long to try all those possible combinations, and programs exist (and are easy to get) to do exactly that.

About password cracking

In addition to the standard American or English dictionaries that we're all familiar with, there are also "crackers' dictionaries." These are collections of common computer terms and phrases, names, slang and jargon, easily typed key sequences (like "querty"), and scatological phrases that one might be tempted to use for a password. These crackers' dictionaries are frequently updated and shared; programs to crack passwords are distributed with copies of these dictionaries. A frequently used method for cracking passwords is to get a copy of the password file for a system, thus getting a list of all the encrypted passwords on the system. The would-be cracker then uses his/her own computer to attempt to crack the encrypted passwords; this activity is undetectable by the system administrator since it is happening on the cracker's computer. If even a single password can be cracked, the cracker can login to the system and begin probing, as a user of the system, for security holes. There are other programs, also easily gotten, that are designed to quickly and easily probe and exploit all known security holes. (It used to require some intelligence and sophistication to be a successful cracker; this is no longer true.)

In Department of CSIS all student passwords are checked weekly. If your password is cracked, you will be issued with a warning and asked to change your password immediately. A list of all Cracked passwords is available on blue noticeboards each week. If your password is cracked a second time, your account will be temporarily disabled.

How to choose a password

Pick a phrase that has some meaning or significance to you, but not to anyone else. Then transform it in some manner so that the final result is consistent with the guidelines above. When transforming, try to transform entire syllables into a single character; do not use an obvious letter-into-digit transformation more than once or twice.

Can't remember your Password?

If you have forgotten your password you can call to either of the student support staff (Redmond O'Brien or Liam O'Riordan) to have your password reset from Week 2 onwards between 12-1pm every day.

Choosing your desktop session

As mentioned in the introduction to linux there are a number of desktop sesions to choose from. This can be done at log in. In the login menu click on session and then the relevant session. At this point you can always set the default session to either KDE or GNOME.



Department of computer science and information systems
University of limerick, limerick, Eire

Department of Computer Science and Information Systems, University of Limerick, Limerick, Eire
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