Home → About → Facilities → Lab Policies
OverviewOur system is funded to support computer science and math courses and research. All Computer Science and Math faculty, staff and students are given courtesy accounts on our UNIX system, as are CS alumni. Course instructors can also request PC accounts for their students on the lab PCs. The following are the system priorities:
- Computer science courses and funded faculty research (most machines are earmarked for one or the other of these purposes).
- Other math and science educational and research activities.
- General education and information services.
CleanupUNIX files with certain 'well-known' names, and files with certain patterns in their names are subject to being deleted without notice. It is up to you as a user to avoid these patterns when naming your precious files. Many UNIX utilities leave behind intermediate, scratch or log files which are meant to be useful to the user. It is logically up to the user to delete these files when they are no longer useful, but few folks do so. Therefore, on a regular basis, system daemons search for files with certain names or patterns and SILENTLY DELETE them in order to conserve disk space. From time to time, especially as the end of the semester comes near, system administrators run additional cleanup scripts that do a more thorough job of finding and removing junky UNIX files. Files in any directory with the following names are considered as trash files:
a.out, core, .places Files in any directory with the following patterns are considered as trash files: (Note that these are regular expressions where * is a wildcard, etc.)
utility pattern exampleOn the lab PCs, we recommend that students not leave any files on the local C drive. These files will be deleted without notice. Students should leave their work in their UNIX home or course directories.
ld *.o main.o
emacs #* #myfile
*~ myfile~ *.bak myfile.bak *.esv myfile.esv
DepartmentSee "University" for reference to the University policies on unauthorized access to computer files. Please note that the computer science department defines "unauthorized access" to include sharing passwords. We cannot distinguish this from accounts which have been "cracked" because the passwords were insecure. There is no reason whatever for anyone else to have your password. We will routinely disable any accounts which appear to be used by anyone but the registered user. In general, intentional violations of the security of the network are not tolerated. If you have a research or coursework need to deal with security related software, you must have a faculty sponsor and must discuss your plans and results with the system administrator. If you are working on a team programming project, or need help communicating with a user at another site on the Internet, please see the Operator or System Administrator. We can help you find a way to work without sharing passwords. (Individual instructors have different policies about group projects. Those instructors who allow group projects will require you to credit joint work.)
DowntimeFrom time to time system administrators need to take timesharing hosts out of service so they can perform maintenance. Such maintenance includes unmounting file systems, rebooting hosts, testing new kernels, et cetera. In order to minimize disruption, we schedule a couple of periods each week for such maintenance. With well-defined maintenance periods, administrators and users can more easily stay out of each other's way. Whenever possible, maintenance will be performed during these periods. With unscheduled maintenance there are, by definition, no such guarantees. Please know this policy:
ANY and ALL SYSTEMS are subject to go down with short notice or NO NOTICE during the periods of 7AM - 12PM on Tuesday and Thursday. Now many times there will be no maintenance that actually makes it impossible for users to do their work. The systems will generally be up and available. But should the system administrators need to reboot a host or something, they may do so with very little (or NO) warning. During maintenance periods, users work at their own risk and should take appropriate actions. For example, they might keep backups of the few files they change during their session. When it is necessary to schedule a shutdown outside the normal maintenance periods, we will post a notice to msgs and mail it to the local mailing list shutdown-schedule. Users who tend to login for very long periods may not read msgs, and may want to get on that list. Do so by sending mail to shutdown-schedule-request, with the commands
endeach alone on a line.
Usually the host going down says its name in the broadcast shutdown messages. Please, when you see system shutdown warnings, log out if appropriate. If you are logged in on that host, or if your home or class dir is served by that host, you should log out. If the mailhost is going down you should quit all mail reading apps. It makes a problem when users have sessions running that are using NFS mounts. Sometimes client hosts cannot unmount NFS filesystems where users have open files. That often makes it necessary for us to reboot more hosts than we should have to, which hurts users.
PrintoutsWhen you pick up a job at the printer make sure to take only your own output. Anything else you find there you should stack neatly and store in the appropriate box. Put any waste papers in the recycling bin next to the refrigerator, and any blank paper in the boxes labeled "blank paper". Remember to leave the printer on.
File PrivacyEvery person has a right to privacy, and a duty to respect the rights of others. Although the default file permissions of UNIX make everything publicly readable, this does not imply that you are welcome to examine anything that the operating system will allow you to. It often happens that new users are not aware of security considerations or how the file protection commands work. Even experienced users may forget to protect their sensitive files from reading. In order to help you protect your rights and respect the rights of other users, here are some simple rules:
- A directory anywhere under a user's home that is named "private" shall be treated as such. Do not examine the contents in any way, even if the permissions are set so that you could. Don't even list the directory.
- Sub-directories of a user's home that are named for courses (e.g. CS241) should be considered private unless the course instructor has allowed the students to share certain information AND the user has not protected the files. Neither condition is sufficient by itself.
- Note that it is incorrect to make one's home directory be unreadable. Certain system utilities, as well as instructors and graders going about their business, need to be able to cd into the homes of students without having to invoke superuser privilege. Keep your private files under your home, in subdirectories with appropriate names and permissions.
- If you are a privileged user, then you must be especially circumspect. Only use root privilege to defeat file protections when it is necessary for the well-being of the system and community, or on behalf of the user.
Use of Copyright MaterialBy law, individuals generally can make copies of small portions of copyrighted material for their personal use. This is called "fair use". Exactly what constitutes fair use is often a matter for courts to decide. See the WebLaw FAQ for discussion of these matters. As the FAQ suggests, you are usually better off making a link to material rather than copying it In any case, the use of the Math and Computer Science Departmental Network subjects you to stricter policies than might be accorded you publishing in a public forum such as a commercial ISP or a book you might publish. Whether or not a court would declare it fair use, you may not post on our servers, email to anyone, or post to newsgroups the entirety, nor even significant portions, of copyrighted materials without the permission of copyright owner. We will not enter into discussions of what is a significant portion or what is fair use. Follow the same rules you learn about for writing papers: use of a few sentences, fully attributed, is OK. More than that usually is not. A copyrighted image is not. Finally note that just because something doesn't have a copyright notice on it does not mean it has no copyright. Your best strategy is to assume anything you find on the web is copyrighted and if it does not explicitly carry permission to copy, or if you do not have written permission to copy it, you should just link to it. See the aforementioned FAQ.
PasswordNever share your account and its password with anyone. It is ABSOLUTELY against the rules to share password with ANYONE (even someone who works here; we will never ask for your password). Sharing your password may result in losing your UNIX or PC account. We monitor account usage. Several people have told us that they shared passwords in order to give non-UMass friends access to their files, or to software here. It IS possible to share files without sharing your password. There are four ways to do this:
- E-mail them.
- Make a copy on a CD or memory stick. Tried and true.
- Make the files available under your public_html. We support web pages and this is a good way for a one-time movement of large files.
- For software, get sources from the original source. All of our public domain software was obtained from public sources. We can point you to the original site where you may obtain the complete distribution for free. If it's NOT public-domain, of course, it must not be copied!
ResourcesThe general resource policies are: Share, give priorities to academic use and don't tie up resources that you aren't using. Here are some specific guidelines. We spell these out so that you can get a good idea of what reasonable use is. We enforce these limits to make sure that everyone gets a fair chance to use our resources. Repeated or deliberate violations of these guidelines may lead to loss of your account. Disk usage: Students are asked to keep home directory use under 200 MB and 50 MB for alumni. This restriction is tight to allow us to use more disk space for courses and projects. Old course work should be removed. Please don't keep personal copies of files that are on the system already: learn how to use
lnto make links. Also please don't keep copies of files that you can get via ftp, or the World Wide Web. Laser printers: Be very careful not to print out non-text files. Please print only what you intend to read. Don't print 1-megabyte mail files to avoid having to read them. Use printer lj3 for large files. The UNIX
mpagecommand is a wonderful utility that can print 2, 4, or 8 pages on a single sheet of paper. Also, please do not take paper from printers for other purposes.
File RestoreTo restore old course directories, please send email to operator(at)cs(dot)umb(dot)edu with the following information:
- What semester you took the course
- Course number
- Instructor's name
- We ask everyone to keep disk space usage to a minimum. In no case should personal usage exceed 50 MB.
- If you are keeping large files for a group project in your account please see your instructor to arrange a more suitable place.
- We erase all course directory trees on UNIX servers at the end of a semester. For example, we do an
/courses/*/f05for Fall' 05 courses. Users who will be working on incompletes need to make arrangements with the course instructor before the end of finals week.
- YOUR FILES MAY DE DELETED WITHOUT NOTICE by system administrators if your disk usage is exceeded and you are deemed to be a disk hog. If we are forced to clean up your directory for you -- "you will almost certainly not agree with what we think you don't need".
- All files left on the PC’s C: drive will be deleted without notice and they cannot be restored.
SecuritySystem staff work hard to keep our computer system secure from break-ins so that we can keep the system up and working. If you are interested in computer security, or see any problem with our system, you are welcome to share your ideas with the system staff. If you want to do any investigations into system security, YOU MUST TALK WITH SYSTEM STAFF FIRST!. If you use any sort of software "cracking'' WITHOUT PERMISSION the penalties will be severe. The System Staff are very available for discussions of security and other system issues, IF you talk with them BEFORE taking any action. Protecting Your Account (Local Users) Your instructor will probably ask you to protect any homework you create from the view of others. The general philosophy of UNIX is to share information as much as possible by allowing everyone with a username on a system to read all material created by anyone else, unless specific protection steps are taken. Your course directories are protected, by default, but your home directory is world-readable. See the GUIDE article on UNIX File Protection. Be careful to pick up any hard copy homework printouts immediately after printing. Sharing your password with friends, family, or classmates is against the rules, because when more than one person accesses an account, it is extremely difficult to tell if the account is also being used by a system "cracker.'' If you need to share files with a teammate, send email to operator(at)cs(dot)umb(dot)edu and ask for a project "group'' which will allow you to create shared files. There are several things you can do to check the security of your account. The
lastcommand shows your last login time.
last -10will show your last ten logins. If
lastshows logins that do not look familiar, please tell the System Staff! The command
ls -laRt | morewill page through all of your files, including "hidden'' files, in reverse order of date. Many UNIX programs make "hidden'' files, which are files that start with a ".'' and are only shown with the
ls -acommand, such as
.elmrc. System "crackers'' often leave extra hidden files in cracked accounts, hoping that the real user will not notice; if you see any unusual files please let us know. When you are working in the public terminal room, NEVER leave your terminal unattended when you are logged in. It only takes a few minutes for a bad person to use your account to do damage. Finally, choose a good password and change it frequently. Never use the same password on more than one Internet account! Password "cracking'' programs have been written that test passwords against dictionaries and lists of names, so your password should never be a dictionary word. There are dictionaries available for dozens of languages, from Arabic to Zulu, so do not use a word in ANY language. These programs also know common tricks like using a "1'' instead of an "l'' or a "0'' instead of an "O'', so a password like "sch001'' will be caught! Here's a good trick for memorizing passwords: take a phrase or saying and use the first letter of each word, mixing up caps and lower case and using special characters wherever they fit. For example, take the phrase "One for the money, Two for the show'' and turn it into "14tm24ts'' . UNIX passwords can be longer than eight letters but only the first eight letters count. PC passwords must contain 7-14 characters, two numbers or symbols in the first 8 characters, and five different characters (letters, numbers, and symbols). Physical Security and the Labs (Local Users) If you are the last person to leave a lab, please close and lock the doors. Because our buildings are not locked, it is very important to keep the labs locked when they are not occupied! You need to contact campus security to gain entry to the lab if the doors are locked. Please do not eat any hot food and food that can easily be spilled in the labs near computers.