General Questions
E-mail
Printing
Teaching
Mathematical Computation
Web Server
General Questions
Q: How do I get an account on the Math department computer system?
A:
New faculty and graduate students in the Ph.D. program should see Peter Woit in Room 421 soon after they arrive to set up a computer account. Visitors who are here for more than a day or two and would like to use the computer system should also see Peter about this.
Q: How do I get an account on the main university computer system?
A:
All new faculty and students should set up an account on the main university computer system. To do this you need to know your "UNI", which is generally your initials followed by a number. You should be able to get this from Terrance Cope. The university web-site for managing UNI accounts is
here.
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E-mail
Q: Why am I getting so much spam, can't something be done about it?
A:
The math mail server is under continuous attack by an overwhelming amount of spam and virus-laden e-mail. Typically at least 95% of incoming mail is spam or viruses. The server is becoming increasingly heavily loaded trying to deal with this onslaught.
We are using three main systems to deal with the problem:
1. The mail server rejects incoming connections from addresses listed on various "BlockLists" which try and maintain lists of addresses used by spammers including PCs that have been trojanned and are being used to send out spam and viruses. The main problem is such PCs, which often each time they are turned on get a new dynamic address.
2. A virus detector called "ClamAV" scans all mail for viruses and rejects virus-laden mail. This is run by a program called MimeDefang, which also rejects all mail containing certain categories of attachments that are rarely used except by viruses.
3. A Spam detector called "SpamAssassin" analyses all the rest of the incoming e-mail and assigns it a score based on a very complex algorithm using many different rules. Higher scores mean higher probability that the e-mail is spam. The algorithms used incorporate Bayesian learning techniques. One reason for some of the random looking spam you see is that it is an attempt by spammers to defeat or poison this kind of analysis. E-mail with a spam score of 9 or above is automatically deleted and not delivered. I have never seen a legitimate piece of e-mail with score 9 or above. E-mail with scores above a value that you can change yourself by editing the value of "required_score" (or "required_hits", same thing) in the file
.spamassassin/user_prefs
is tagged in the subject line as "SPAM". The default value is 7, you may want to try making this smaller. Smaller values will identify more spam, but will increase the probability of misidentifying legitimate mail.
You can also blacklist and whitelist specific addresses using "blacklist_from" and "whitelist_from" entries in the user_prefs file.
If you want to automatically do something about the mail tagged as "SPAM", you can do so by putting an appropriate ".procmailrc" file in your home directory. If you do
cp /usr/local/etc/procmailrc.deletespam .procmailrc
all such mail will be automatically deleted before you see it.
If you do
cp /usr/local/etc/procmailrc.savespam .procmailrc
all such mail will be saved in a mail folder called "Spam". I've been doing this for a while, and have never seen a legitimate message to me ending up there, using the default cut-off of 7. If you do this, please empty this "Spam" mail folder regularly. If you accumulate a large one, it will sooner or later be deleted without asking you.
Q: How do I forward e-mail from one account to another?
A:
To forward e-mail from your central university account, go to the CUIT site that provides management of your UNI account (currently here).
To forward e-mail from your math department account to another one (e.g. to a gmail account), you need to create and edit a file in your home directory with the name ".forward". If you are not used to using Unix, the simplest way to do this is to logon to math.columbia.edu via SSH, e.g. by clicking on the "SSH" button in the upper-right-hand corner of the main department web-site. Once you have logged in, type
pico .forward
which will allow you to edit the .forward file.
If you just want all mail automatically forwarded to another account, e.g. "user@gmail.com", just put that address in a single line
user@gmail.com
then quit the program, saving the file.
If you want to forward e-mail and keep a copy on the math department server, put the following on a single line
\mathusername, user@gmail.com
where "mathusername" is your Math department user name.
Q: How do I set up my favorite mail program to work with the Math Dept. server?
A:
Most mail programs should work with the Math department server, and set-up should just involve giving the program the information it needs about the account.
To read your e-mail, you should set the server address to "math.columbia.edu", and server type to "IMAP" ("POP will also work, but the IMAP server is more powerful and more reliable). You also need to choose the option to encrypt the connection ("SSL), some programs require you to specify the port (993 for IMAP/SSL), but this is normally set correctly automatically.
To send out e-mail (i.e. to specify the "SMTP server"), you can only use the math department server from within the math building (because we currently have no other way of protecting the server from being used by spammers to send out mail). You can use the main university system to send out mail, see here. If you are getting your internet service at home from some ISP other than Columbia, they should also be providing an SMTP server that you can use.
Q: How do I read my e-mail on the Math department computer system?
A:
The two simplest mail programs to use are:
Pine: this is a text-based program that does not require a graphics environment, and so can be run from any terminal window on the Linux machines, or any terminal program on another computer. It can be started by typing "pine". For more information about its features and how to use them, see the web-site of the Pine Information Center.
Webmail (IMP): this is a web-based program that provides access to your e-mail using the department web-server. It can be used from any web-browser on any computer attached to the internet. The program is started by clicking on "Email" in the upper right-hand corner of the department web-site (or here).
Other mail programs (Thunderbird, Outlook, Apple Mail, etc.) can be used to access mail from the math server using either IMAP or POP. If possible, use IMAP. You will need to choose the SSL version of IMAP, the one that encrypts the connection. To send out e-mail you need access to an "SMTP server", but cannot use the math server for this since we currently have no way to keep it from being used by spammers if we allow this. If you are using a commercial internet service provider, they should provide an SMTP server address you can use. You can also use the main Columbia mail server. See the pages about e-mail on www.columbia.edu for instructions on how to set this up.
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Printing
Q: What is the Unix name of the printer in (location)?
A:
The default printer for the Linux system is the one in Mathematics 421. If you are using this you do not need to specify a printer name. Other printers in semi-public locations are given names according to the scheme
"RoomNumber"Printer, e.g. the printer in 421 is
421Printer, the one in the fourth-floor graduate student office is
408Printer. One exception is the color printer in the main office, room 509, which is named 509ColorPrinter. Printers in individual offices are given names according to the scheme
"LastName"Printer.
For a complete current list of the department printers, see the
CUPS Printers web-page on the Math department web-server.
Q: How do I set up printing to a printer from my Mac or PC?
A:
You can print directly from a Mac or PC to any of the departmental printers. When you set this up, the crucial information is the internet name or IP address of the printer, and the type of printer. Here's a list:
206B: lp206.math.columbia.edu 128.59.192.102 HP Laserjet 4240
408: lp408.math.columbia.edu 128.59.192.103 HP Laserjet 4240
421: lp421.math.columbia.edu 128.59.192.100 HP Laserjet 9000
509 Color Printer: lp509.math.columbia.edu 128.59.192.101 HP Color Laserjet 3000
509 Black and White Printer: lp509bw.math.columbia.edu 128.59.192.116 HP Laserjet 4240
Undergraduate Lounge: lpundergrad.math.columbia.edu 128.59.192.121 HP Laserjet 4250
Copier on 5th Floor: copier.math.columbia.edu 128.59.192.93 Canon imageRunner 5055
Setting direct printing up is done differently on different operating systems. Note that for some versions of Windows you need to select "local printer" and set up a network printing port with the right address. Using "network printer" will often not work since it will look for and find Windows computers that it thinks are print servers. You may not have the drivers for the precise type of HP printer, but this normally does not matter, you should be able to choose a similar HP model number.
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Teaching
Q: What is Webwork?
A:
Webwork is a system for on-line homework assignments developed at the University of Rochester. At the current time we are using it in our Calculus I and Calculus II classe. These classes have a teaching assistant assigned to them who is responsible for Webwork issues, and who should be able to provide help with any problems you have in using the system.
Q: What is Courseworks?
A:
Courseworks is the university's on-line course management system. You can use it to set up web-pages for your course, maintain grades, and make available assignments and other material to the students.
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Mathematical Computation
Q: What mathematical software is available on the department system?
A:
The department Linux machines have installed a wide range of open source mathematical software. If there is some package you would like to use that is not there, please let Peter Woit know and it probably can be installed.
Among commercial packages, the department has a site license for Mathematica, it should be installed on all our machines. We also have a 2-user Maple license on the Linux machines. If you run Maple on a Linux machine, please quit the program when you are not using it, to ensure that the license is available for others to use. We also have several licenses for Matlab on the Linux machines.
Q: What computers are available for long computations?
A:
Please do not use the main server (cpw.math.columbia.edu=math.columbia.edu) for time-consuming computations. These can be done on any of the local Linux workstations. In the past we have had a dedicated server available for computations, but unfortunately this machine is now down. This fall we should be acquiring a new one, and when it is up and running information about how to use it will be posted here.
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Web Server
Q: How do I create a home page for myself?
A:
Your home directory should contain a sub-directory named "html", and any file you put in it will be accessible to the outside world. If your math department user name is "username", and you put a file named "file.html" in this sub-directory, it can be accessed as
http://www.math.columbia.edu/~username/file.html
The default file name is "index.html", so if you create a file with this name, it will be accessible as
http://www.math.columbia.edu/~username
By default the web-server does not list the files in your html directory to the outside world, so one relatively secure way of making files available just to a specific person or small group of people is to just give them an unusual and difficult to guess name. Only people who know the name will be able to access the file.
There are many ways to create html files. Since these are simply text files, the crudest is to take an html file that is close to what you want, and just edit it with a text editor. Modern versions of Microsoft Word and many other word-processing programs are able to save files in html format. On the Linux systems, the "seamonkey" browser provides a "Composer" mode which allows creation and editing of html files, and "amaya" is a powerful html editor. There are many commercially available full-featured html editors for Mac and Windows, Dreamweaver is perhaps the best known.
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