The most up-to-date version of this document can be found online at http://support.phys.cmu.edu/faq.html
Patches and solutions for annoying software behavior, with binaries compiled for different linux distros: Redhat 7.3, SUSE 9.3, SUSE 10.1.
|How do I get help with computers?|
|What computers are available?|
|What is an andrew computer?|
|What is a qwe or phys private computer?|
|How can I access the Parallel Cluster?|
|What public printers are available? Where are they located?|
|How do I use the phys public printers?|
|Which are my e-mail accounts? What e-mail reader should I use?|
|How do I know what commercial software is available?|
|How do I access a computer remotely?|
|How do I transfer files from a remote computer?|
|What are the security implications of working on remote computers?|
|How can I pick and remember an unbreakable password?|
|What's a list of andrew computers?|
|Why ssh/scp to andrew computers do not seem to work well?|
|How can I create my web page?|
|What should I use to edit/maintain web pages?|
|Are there any spam filters available?|
|How do I configure my mail clients to access different mailboxes?|
|How can I access the Usenet and the CMU BBoards?|
|How can I post on Usenet newsgroups and on the CMU BBoards?|
|How do I create a good looking pdf file starting from a dvi file in Linux?|
|How do I know that a pdf file will look good on any platform?|
|How can I speed up Matlab 6.x?|
|How can I visualize data in Linux?|
|How can I create movies in Linux?|
|How can I view movies/listen to music on qwe or phys computers?|
|How can I create mp3's in Linux?|
|How can I edit a sound file?|
|How can I use the scanner from Linux?|
|How can I burn CDs/DVDs from Linux?|
|What command should I use to do "that task"? How should I use this command?|
|How can I find more about computers?|
|What matlab/maple/mathematica clones developed by the scientific community are available?|
|What spreadsheets are available in Linux?|
|What word processors are available in Linux?|
|How do I configure OpenOffice the first time I run it?|
|How can I create slides or PowerPoint-type presentations in Linux?|
|How can I see/edit/print Microsoft Word/Excel/Powerpoint in Linux?|
|How do I configure mail clients to access different mailboxes?|
|What's the IP setup for a .phys computer in Wean Hall?|
|How do I connect from home to the CMU modem pool?|
|How do I forward my e-mail?|
|How long will my account last after I'm leaving?|
How do I get help with computers?
For the operation of the University maintained (andrew) computers and printers, please contact the Help Desk, or call 8-HELP.
For Windows and Macintosh computer problems and questions, please contact Al Brunk (DH Ma 332, ext. 8-2736).
For linux/unix Physics Dept maintained computers, clusters, scientific projects, programming, and applications, please contact Florin (Wean Hall room 6108, or call 8-3158).
What computers are available?
The users have access to a set of University maintained computers named andrew computers, and to private computers administrated by the Physics Dept.
Most of the public printers in the Department work as both andrew and private printers.
Each user gets an andrew account and password. This account should work on all the public andrew computers in the campus, including the computers in the public clusters.
What is an andrew computer?
The andrew computers are University maintained computers having:
|a shared filesystem (AFS) which allows the user to see the same files from any andrew computer;|
|Kerberos security for the remote services (telnet, ftp, e-mail);|
|centralized distribution and customization of software packages, upgrades, licenses, etc.|
Each CMU user gets an andrew account and a 20Mb disk quota to store files and another 20Mb quota for e-mail messages. To increase your quota see here.
The andrew computers in the Physics Dept are Intel platforms running Linux. The operating system is heavily modified to support the andrew characteristics. The andrew computers are configured with user-friendliness and easy access in mind.
In the public clusters one may find Windows XP based andrew workstations.
What is a qwe or phys private computer?
The Physics private computers are Linux computers configured for performance.
They consist in:
|Computers in many of the offices of faculty, staff, postdocs;|
|the qwe cluster which is a group of PCs named qwe1-qwea, sharing user home directories on a high speed network segment; presently the qwe cluster is located in Wean Hall 6403b;|
|the parallel cluster which is a group of multiprocessor high end PCs sharing the user home directories with the qwe cluster; the computers in the parallel cluster are interconnected via a switched Fast Ethernet network; these computers are loaded with software as PVM and MPI which takes advantage of network communication in order to handle parallel computations.|
The access on the cluster computers is granted to Physics faculty and students, based on their andrew account and upon request. The office computers are accessible only by the occupants.
There is no enforced quota and CPU time limitations. However these systems are permanently monitored against abuse.
The only incoming accepted connections are ssh and scp.
The ftp and telnet outgoing requests are Kerberized and match the andrew servers, so the respective connections are encrypted only to andrew computers. To any other computers, telnet and ftp are unsecure. For telneting to andrew computers it is recommended to use first "kinit" to get Kerberos tickets once every 25 hours, then "telnet -af andrew_computer_name" for automatic login.
The Cyrus mail IMAP connection is also Kerberized if used with the "anpine" command paired with "kinit".
How can I access the Parallel Cluster?
The computers in the parallel cluster are accessible only remotely, having the following names: fp21-fp29. The only accepted connections are ssh and scp.
All the users of the qwe cluster can access those computers. However, they are intended to be used only for number crunching purpose, and not for e-mail, file editing, web surfing or other graphics intensive applications.
What public printers are available? Where are they located?
The first class of public printers are the andrew printers maintained by the Computing Services. They can be accessed from the andrew computers via the "lpr" and "print" commands. The list and the location of those printers can be obtained from the Help Desk.
Other public printers are the ones maintained by the Phys Dept. They act as regular andrew printers when accessed from andrew computers, and can be used from the private computers via the "lpr" command. The private computers interface allows a larger set of filters, which means a larger number of file formats can be sent directly to the printer.
Here is a list of the Phys public printers:
|Printer name||Location||Hardware Description||Known limitations||Queues
|code||Wean Hall 6403b||HP LaserJet 8100 ND
|None||code - one side
dcode - two-sided, flip on long edge
dscode - two-sided, flip on short edge
|osage||Wean Hall 6403b||HP LaserJet 8150 ND
|None||osage - one side
dosage - two-sided, flip on long edge
dsosage - two-sided, flip on short edge
|hpcolor||Wean Hall 6403b||HP Color Laserjet 4500
How do I use the the public printers?
Use "lpr -Pqueue filename", where queue should be used as described previously.
The printers have a private spooler which offers the following additional features:
|"lpr" automatically handles the following file formats: text, postscript, pdf, dvi, gzip, troff, pbm, gif, jpeg, and most bmp files;|
|the printer "code" can be used to print double-sided when referred as "dcode" or "dscode"; the same procedure works for "osage"
Known problems with the private spooler:
|When printing a dvi file which contains references to postscript images, the images may not be printed since the corresponding files are not sent to the printer. To get around this, either build a postscript file which contains the images and print it, or include the full path when specify the filenames containing the images.|
Which are my e-mail accounts? What e-mail reader should I use?
Together with the andrew account comes an andrew e-mail account: firstname.lastname@example.org
where user stands for the andrew ID/login name. The andrew e-mail system is called Cyrus.
The Cyrus system is a modern system based on Kerberos and the IMAP protocol. The Cyrus mailbox can be accessed by the "pine" application on andrew Unix computers, or "anpine" on the qwe and phys private systems. For Windows and MacOS, the Computing Services recommends "Mullberry".
On the andrew e-mail systems Usenet newsgroups and local Bboards are available upon subscription. The e-mail reader is used also as newsreader.
A completely different e-mail account is available to the users of the qwe cluster. The e-mail address is email@example.com
This account can be accessed only from the qwe machines, using the "pine" e-mail application configured to use IMAP. Any other IMAP compatible mail readers should work equally fine if configured to use pubs.phys.cmu.edu as the incoming mail server and localhost as the outgoing mail server.
On the physics private computers in the offices, each account is associated with a third e-mail account: firstname.lastname@example.org
This account can be accessed by any the standard e-mail reader.
Since an user may have two or more e-mail accounts, it is advisable that all accounts but one should have the forwarding feature activated such that all the incoming e-mail goes to one account.
How do I know what commercial software is available?
A list of software licensed by CMU can be found at http://www.cmu.edu/computing/software
Most of those packages are installed on the andrew computers.
The qwe and Phys private computers come with a version of Redhat Linux, modified to be as compatible as possible with the Kerberos and e-mail services offered by the Computing Services for the andrew computers, and with a set of University licensed commercial packages installed.
If you have interest in a software package which is not installed, or in a service which is not already offered, please contact Florin.
How do I access a computer remotely?
Use the "ssh remote_computer" command, where remote_computer is the name of the computer you want to access. If your computer does not have the ssh software installed, please contact Florin to get a free copy for your operating system.
If there is no way to get ssh installed and working on your computer, you can use the command "telnet remote_computer". Unless remote_computer is an andrew computer AND your telnet is kerberized, your login name and password will be plainly disclosed on the network. Please see the security implications below.
How do I transfer files from a remote computer?
Use the "scp remote_computer:source destination" command, where remote_computer is the name of the computer containing the file, source is the name of the file you want to get, and destination
is the name given to the file on the local computer. If the file should
be moved from the local computer to a remote computer, use "scp source remote_computer:destination". If the login name on the remote computer is different, it has to be specified as in
"scp source remote_loginname@remote_computer:destination". Please see the scp manual page for more details.
If your computer does not have the scp software installed, please contact Florin to get a free copy for your operating system.
If there is no way to get scp installed and working on your computer, you can use the command "ftp remote_computer". Using ftp, your login name and password will be disclosed on the network. Please see the security implications below.
What are the security implications of working on remote computers?
The first security problem appears when you use unencrypted communication channels, as telnet, ftp, and the un-kerberberized IMAP and POP e-mail clients (eudora, netscape, outlook, etc). All those applications authenticate the user by sending the user name and the password in clear on the network.
Specialized programs named sniffers are used for network monitoring. These programs, which are publicly available on many ftp sites, can be easily configured by crackers to listen the first few minutes from each newly opened connection and to pick the username/password.
On most of the networks there are sniffers running on broken accounts. If your connection is passing through such a network (and probably it does), your login name and password will be stored in the sniffer's log file and may be used later to compromise your account and/or to run a sniffer under your name and to pick more passwords on your local network. The sniffers have a passive attitude, so many of them cannot be detected from the network, and an user without special training will never realize that a sniffer is running under his own account. As a result, the crackers have available huge archives of broken accounts from most of the networks. These accounts may be used at some undetermined moment to launch illegal activities or to destroy your data.
What can you do:
|do not ever use ftp and telnet -- use ssh and scp instead; find out if the connection is encrypted each time you have to use a password or any other important confidential information which goes to a remote computer (as in the case of most of the e-mail services, subscription to different financial services offered via the web, e-commerce, etc);|
|if you are using telnet or ftp, you can minimize the exposure by changing your password a few minutes after the login. The sniffers listen only for the first few minutes from a newly opened connection. After that, if you change the password, the new password will not be recorded, and the password already recorded by the sniffer will no longer work;|
|change your passwords at least twice a year, just in case;|
|report to Florin any suspicious activity inside your accounts.|
Another important security problem appears when you are trying to send windows from one computer to another using telnet and X-Windows. An window can be exported only if the local X-server has set permission to give up control of the display/keyboard/mouse to the remote computer. This should be achieved by the command "xhost + remote_computer" issued on the local computer (see the xhost manual page). The xhost command opens a huge security hole because it gives to any user of the remote computer rights to control the behavior and to monitor the display, the keyboard, and the mouse of the local computer. The only secure setting of xhost is "xhost -" which denies any access, except for the local user.
What can you do:
|do not include in your login scripts any variation of the "xhost +" command; make sure that "xhost -" is the default;|
|use ssh instead telnet; the whole communication will be encrypted and compressed/faster; windows can be exported without changing the xhost setting -- ssh tricks the X-server into believing that the remote display is a local one; do not change the DISPLAY environment variable from the value which was set by ssh, even if it looks as nonsense to you -- it will blow up the whole security.|
What is my password? How can I change it?
You may have several independent passwords:
The andrew password is automatically generated when you get the andrew account, and it should be changed ASAP. The andrew password provides you access to all the andrew computers, and to the andrew e-mail account.
The qwe password grants you access to the qwe computers, to the parallel cluster, and to the e-mail on the pubs server.
If you have accounts on one of the private Phys computers, you should have an additional password for each account, to access the local computer and the local e-mail.
The password can be changed with the "passwd" command.
Changing the password on one andrew computer will propagate the change on all the other andrew computers. Changing the password on one qwe computer will make the change on all the other qwe computers.
It is not a good idea to have the same password associated with different accounts.
It is not a good idea to use the following types of password:
|based on a (slightly modified) dictionary word, even in a foreign language;|
|based on some information connected to your person (car numbers, phone numbers, SSN, birth date, etc).|
Those passwords can be guessed easily. One weak password endangers the work of all the users of that system, so please show respect.
How can I pick and remember an unbreakable password?
Create a password from the first letters of the words in a sentence you can easily remember.
E.g. the sentence: "Oh, how nice are Jane's shoes!" will generate the password "OhnaJs", and if you add to it a digit (or a special character), you'll end up with something like "OhnaJ3s" which cannot be broken by brute force algorithms.
What's a list of andrew computers?
Most of these computers are in public clusters or public places. So they can be down or rebooted or misconfigured at any time. If one does not work for you, try another one.
Why ssh/scp to andrew computers do not seem to work well?
SSH/SCP applications are based on keys of individual computers to realize the encryption. Doing ssh or scp to andrew.cmu.edu or unix.andrew.cmu.edu (that are not individual computers, but generic name for a pool of computers) will use one computer in the pool (say unix3.andrew.cmu.edu) for the connection. Next time ssh is used to the same andrew.cmu.edu, the connection is done to another computer in the pool having another key. So ssh/scp complains about a possible problem and sometimes aborts the connection.
SOLUTION: use ssh/scp to individual andrew computers from the list above; delete your ~/.ssh/known-hosts files if annoying messages pop-up, then try again.
How can I create my web page?
It is possible to get disk space for a web page under the www.cmu.edu tree. Details about how to request this can be obtained from the Help Desk.
However, most of the Phys Dept users prefer to build their web page on the web.phys.cmu.edu server. In order to do this, you have to:
|get an account on the qwe computers if you do not have one yet;|
|put your files (including an "index.html" file) into the "public" folder which comes already configured in the home directory of your qwe account;|
|give the right set of permissions to the files you want to make public in the "public" folder; use the "chmod a+r filename" command to give read permissions, where stands for the file(s) you want to be accessible on your website;|
|access your web site as http://web.phys.cmu.edu/~userid/
where userid is your login name on the qwe computers.
Any changes in the web files content will show up instantly if you are using the above procedure. Just hit the "Reload" or "Refresh" button of your web browser.
What should I use to edit/maintain web pages?
A simple website can be created and maintained using the mozilla web editor.
However, if a more complicated site is desired, more advanced tools are needed. A good Open Source HTML editor (not WYSIWYG) is Bluefish. It can be used by issuing the command "bluefish" on any qwe or private phys computer.
Are there any spam filters available?
The andrew mail system has a set of filters that can be made effective via https://www.cmu.edu/myandrew/ . Please call the help desk for up-to-date information, legal disclaimers, etc.
There is no spam filter on the normal phys.cmu.edu e-mail account.
WARNING: Spam filters are not perfect. Even if the probability is very low, accidentally messages may be lost. Do not use filtered accounts if you cannot tolerate e-mail loss.
How do I configure my mail clients to access different mailboxes?
Security/privacy considerations. Reading mail implies two stages: authentication to a server and the transport/display of the message contents. Both stages can be performed on encrypted channels or in clear. Clear channels give everybody on the local network access to user's login name, password, and/or e-mail messages.
Transport protocols: POP and IMAP perform transport on clear channels. IMAPS transports the messages via an SSL encrypted channel on port 993. Not all the readers know how to handle IMAPS. Anpine and pine on andrew computers do not encrypt the transport of the messages.
Authentication: Most of the mail readers perform clear channel authentication. Andrew provided clients (pine on andrew computers, anpine on phys computers, mullberry) use Kerberos encrypted authentication. IMAPS activated readers are doing authentication on encrypted channels.
The configurations below are known to be the most secure for the given setup.
Andrew mail: IMAP, IMAPS, POP available.
Phys mail (default setting - server pubs.phys.cmu.edu): IMAPS only
NOTE: Configuring different e-mail readers to access various mail servers can be confusing and frustrating since the readers treat different mail folders in different ways, so you have to have lots of patience and to understand exactly what are you doing. Optimizing the configuration for one client will almost surely have drawbacks for other clients.
How can I access the Usenet and the CMU BBoards?
The Usenet groups and the local CMU Bboards are offered via IMAP as e-mail folders for the andrew e-mail readers.
Also, there is a public access NNTP server on the CMU campus network: news.club.cc.cmu.edu
Feel free to use it with any news reader.
How can I post on Usenet newsgroups and on the CMU BBoards?
You have to use an e-mail gateway; this is achieved sending your posting as a regular e-mail to "email@example.com", where bboard_name is the name of the Bboard which should host the posting.
How do I create a good looking pdf file starting from a dvi file in Linux?
A dvi file can be transformed into a postscript file optimized to be converted to pdf using the "
How do I know that a pdf file will look good on any platform?
Rendering pdf files depends on the fonts used by the file and if those fonts exist on the reader's computer. The solution to this is using "Type I" fonts which are actually included in the file itself, are scaling well, and will be rendered correctly and nicely by almost any pdf reader.
see what type of fonts are used in a certain pdf document, open the
document in the Acrobat Reader ("acroread" command in Linux), and open
the following menu:
"file" -> "Document Info" -> "Fonts"
The Linux procedure above will generate pdf files containing only "Type I" fonts.
How can I speed up Matlab 6.x?
Because of the graphical interface, many users find Matlab 6 more inconvenient to use and much slower than previous versions. Here are some tricks to get back to the old nice Matlab feeling:
Using the "matlab -nodesktop" command, no extra "desktop" will be created by matlab and the input will be done through the xterm as in Matlab 5. This will speed things out a little bit.
If more speed is needed, "matlab -nojvm" should be used. With this flag, matlab will not start the Java Virtual Machine which takes a lot of computing power and is not used by most of the users anyways.
How can I visualize data in Linux?
Good packages for graphs, interactive graphs, animation:
How can I create movies in Linux?
good way to transform a set of jpeg files into a mpeg-v1 movie is using
the "mpeg_encode" command. Please read the manual page "man
mpeg_encode" first and look for example configuration files in
How can I view movies/listen to music on qwe or phys computers?
If the computer has sound card, the line out connector behind the computer can be used with speakers or user-provided headphones.
Some multimedia applications:
xmovie - mpeg-1,2, mp3, some quicktimes, DVD, wav, AIFF, AC3
xine - DVDs, mpeg-1, mp3, avi, vcd
gtv - MPEG-1, mp3
ogle - DVD
How can I create mp3's in Linux?
A very good application to transform wav files in mp3 is "notlame". If you are handling wav and mp3 files on the qwe computers, please keep them inside a folder named "tmp" that can be created in your home directory, such that the large sound files will not clog the backup server.
How can I edit sound in Linux?
A nice sound/waveform editor/filter for wav files is "audacity".
How can I use the scanner from Linux?
How can I burn CDs/DVDs from Linux?
There are two types of CDs/DVDs that can be used:
There are several flavors of DVDRWs. For maximum compatibility and
reliability reasons, we recommend DVD-RW with a speed rating not larger
The filesystem on CDs/DVDs is ISO9660 which is a fixed type of filesystem: once created no files can be added/deleted. To add or delete files on a CDRW/DVDRW the disk should be first completely deleted and the new filesystem containing the old files plus the changes should be re-created. By deleting the CDRW/DVDRW the old files will be gone if they are not saved in advance.The process of burning a CD/DVD implies several steps:
Some operating systems make the steps transparent to the user. This makes the process "easy to use" but error-prone and with no flexibility. Because of that in most of the cases third party software that reveals all the stages is preferred to the over-simplified interface offered by Windows or MacOS.The Linux application recommended for writing CDs/DVDs is "xcdroast". This application offers a simple direct way to copy CDs/DVDs, and a flexible way to master your own data CDs/DVDs using files on the harddrive. The mastering process consists into the three steps outlined above.
What command should I use to do "that task"? How should I use this command?
On Unix/Linux computers use the command "apropos keyword" to find a list of commands which may do things described by keyword; then use "man command" to find out what does the command do. If you are familiar with emacs, "info command" may offer a nicer interface that can be browsed.
On Windows and Macintosh computers please use the "Help" menus.
How can I find more about computers?
A general purpose course is offered each Spring Semester by the Math Sciences Department.
What matlab/maple/mathematica clones developed by the scientific community are available?
scilab (developed at INRIA) or octave. Both very nice programs as easy to use as their commercial counterparts. There are even filters that convert simple scripts from one language to another.
What spreadsheets are available in Linux?
gnumeric, kspread, OpenOffice (command "soffice"). Recommended: gnumeric
The OpenOffice spreadsheet will read some of the Excel files. Otherwise, Excel files should be saved as text files and will work with all of the above applications.
What word processors are available in Linux?
Of course the power word processor is Latex.
For fans of WYSIWYG applications:
A nice and fast word processor is "abiword". It doesn't have as much features as Microsoft Word, but in the end who is using at least half of those. It can read and create MSWord documents.
Another more feature-rich word processor is the one which comes with the OpenOffice suite (command "soffice"). It can also read and create MSWord documents.
How do I configure OpenOffice the first time I run it?
Choose "Workstation Installation" (default), then pick a directory e.g. "~/.OpenOffice" for the files, browse "/usr/java/j2re.1.4.whatever" for the java interpreter.
How can I create slides or PowerPoint-type presentations in Linux?
One solution (the professional one) is to use the "slides" class in Latex. Or, for nicer graphics, you can use the prosper extensions to Latex (documentation in /usr/share/texmf/tex/latex/misc/prosper).
Other solution: A PowerPoint alike slide creator came with the OpenOffice suite (command "soffice").
How can I see/edit/print Microsoft Word/Excel/Powerpoint in Linux?
Some of those documents (especially those created by Office 97) can be handled by the corresponding applications from OpenOffice (command "soffice"). Some Word documents can be handled by the "abiword" word processor. Otherwise you should use the Windows computers.
What's the IP setup for a .phys computer in Wean Hall?
Nameservers: 18.104.22.168, 22.214.171.124
How do I connect from home to the CMU modem pool?
CMU is maintaining the following telephone line for SLIP and PPP connection of users from remote locations: 412-268-9000
Windows 9x an later, Macintosh MacOs 8.0 and later: follow the standard instructions in your operating system to create a PPP connection using the above telephone numbers and the default settings.
The TCP/IP settings should contain the nameservers mentioned here; the IP, gateway and broadcast addresses are established automatically after the modem connection is done.
Linux: The last known working dip scripts for Linux is cmumain.dip. Please replace "florin" with your andrew ID in the username/password section of the script and check the "port" line to reflect your computer's configuration. The file should be placed in /etc working as user root on the Linux systems installed by the Phys Dept.
Known problems with cmumain.dip:
1. If the cmumain.dip file is downloaded using a Windows machine, the newline characters will be replaced with the ones used in DOS, and dip will not work with the file.
2. At the password prompt, you should type your andrew password followed by \n then press the Enter key. E.g. if your andrew password is "mypass12", the right thing to type at the password prompt is "mypass12\n".
How do I forward my e-mail?
On the qwe and Phys private computers:
|create a .forward file in the home directory, to start forwarding; the file should contain the address to be used for forwarding, or a list of addresses separated by commas on the same line;|
|delete the .forward file to stop forwarding.|
For the andrew mail:
|login to an andrew computer and issue the command "forward new_address", where new_address is the address to be used for forwarding, or a list of addresses separated by commas; the forwarding will start in up to 48 hours;|
|login on an andrew computer and issue the command "forward -z"; the forwarding will stop in up to 48 hours;|
How long will my account last after I'm leaving?
The accounts on the qwe cluster and on the Phys private computers will last for as long as you need to safely move your files. Please talk to Florin about this, before you leave.
The andrew account policies are rapidly changing. Please contact the Help Desk to find out more.