Computer Systems FAQ
(Frequently Asked Questions)
This document is maintained by the Systems Support Group.
It is not an official document of the Computer Science Department
and is provided in the hope that it will answer some of the more
common questions. It is written mainly from a student perspective
but staff and faculty should find it useful as well. This
document is available online at
http://support.cs.iastate.edu/faq.html.
Feedback and suggestions are welcome; please send an e-mail
to ssg@cs.iastate.edu.
This document addresses frequently asked questions
pertaining to the computer systems run by the Computer Science
Department. This FAQ does not cover any more IT topics than
are necessary for you to use the Computer Science machines. For
IT details, check with the Help Room on the first floor of Durham,
or if you have an IT account, just type "olc answers"
at a command prompt. As it is impossible to cover every
aspect and every nuance of each question, feel free to send e-mail
to ssg@cs.iastate.edu
or stop by 0125 Pearson Hall if you need further clarification
on a topic.
You register by using a web browser and going to the
form located at http://register.cs.iastate.edu.
It will ask you for some information about yourself, and if you
are in our account database of eligible users, it will create
both your Unix and Windows accounts for you automatically.
We receive our information about new students on the first day
of classes so you may not be in our database until then.
You are eligible for a computer systems account if you are
an undergraduate or graduate student with a Computer Science
major (single or double major accepted). Non-Computer
Science majors are also eligible if they are taking a Computer
Science class. Note that some classes have their own group
accounts and therefore are not eligible for accounts for individual
students (excepting for Computer Science majors of course).
Accounts for majors of Computer Science will remain active
until the individual leaves the department or the University
(ie. graduation or changing majors). Accounts of non-majors
will remain active until the end of the semester in which they
are created.
You generally have physical access to any of the machines
in the Computer Science student labs. These are all the
labs on the bottom floor (basement) of Pearson Hall. There
are no longer any public labs in Atanasoff Hall. Currently
we have Windows XP and Red Hat Enterprise Linux available for
student use.
The labs are sometimes reserved for course labs and recitations
and may not be open for public use. Lab schedules are
posted outside each lab showing when they are used by classes
and when they are open for public use.
Here is a quick breakdown of the machines currently in the
student labs and available for your use:
| Pearson Lab 0105 |
20 Windows XP |
| Pearson Lab 0109 |
20 Windows XP |
| Pearson Lab 0108 |
20 Windows XP |
| Pearson Lab 0141 |
32 Red Hat Linux |
| Pearson Lab 0113 |
Reserved for COMS 252 |
For remote access, you may ssh to pyrite.cs.iastate.edu for
Unix use or remote desktop to cstc.cs.iastate.edu for Windows
use. Your home directory will be directly mounted from
our main fileservers, so you will have your files available
regardless of which machine or flavor of OS you login to.
Unix machines in the student labs may be accessed by first ssh'ing
to pyrite.cs.iastate.edu and then ssh'ing to the machine you
wish to access. Each machine has a unique name which you
can discover from the login screen. A free ssh client
is available for Windows at the ISU Site Licensed Software website
http://www.sitelicensed.iastate.edu.
Most Linux distributions come with a ssh client installed by
default.
Your Computer Science e-mail address is username@cs.iastate.edu,
replacing "username" with your Unix/Windows username.
This is the address that will allow you to receive e-mail.
To forward mail from your Computer Science account to your
IT account, create a file in your home directory called .forward
(note the leading dot). This file should contain your AIT email
address - for example, username@iastate.edu. The departmental
e-mail server collects .forward files nightly at 2:00am, so
it will not take effect immediately. Note that you can
forward your e-mail to any address you like, not just IT.
Be sure you enter your forwarding e-mail address correctly though,
otherwise your e-mail may become lost!
To forward e-mail from IT to your Computer Science account,
use the chpobox command on an IT machine. For example:
chpobox -s username@cs.iastate.edu would
forward mail received at your AIT account to your Computer Science
mailbox. The command: chpobox -p will undo a forward.
These changes are processed only once a day (late in the evening),
so don't be discouraged when it doesn't seem to do anything
right away.
Be careful not to forward mail "in a loop", that is from IT
to Computer Science and also from Computer Science to IT.
After a certain number of cycles your mail will wind up
getting discarded automatically.
Many e-mail clients (for example Outlook, Outlook Express,
and Eudora) support e-mail filtering on the client side.
This allows, among other things, automatic sorting of mail into
folders and detection/prevention of spam. This is available
for all users.
It is possible to sort e-mail on the server side of the Computer
Science e-mail server if you are a graduate student or staff
member. There are no facilities for undergraduate students
at this time, unfortunately. Graduate students/staff may
ssh to mail.cs.iastate.edu to setup their .procmailrc file.
See the man page for procmail(1) and procmailex(5) for details
on how to set these up.
You may read your Computer Science e-mail using any
IMAP or POP compatible e-mail client. There are many of
these available both free and commercial, GUI and text-based.
Some of the more popular ones include Outlook, Eudora, and Thunderbird.
It is also possible to setup pine and mutt (text based clients)
to access your e-mail via IMAP. Setting up an IMAP/POP client
is easy, just point your e-mail client to imap.cs.iastate.edu
or pop.cs.iastate.edu respectively for incoming e-mail and mailhub.cs.iastate.edu
for outgoing e-mail. Your Computer Science username and
password are required to both receive and send e-mail (though
a sending password is only required for off-campus clients to
recipients outside of the iastate.edu domain). You may access
your e-mail in this fashion from anywhere on the internet, assuming
your ISP does not restrict the e-mail ports.
When trying to decide whether to use IMAP or POP to receive
your mail, we suggest this general rule of thumb. If you
are going to be reading your mail from one primary host (ie.
your laptop or your home computer) then use POP. If you
want to read your mail from several different hosts, including
our webmail service (described below), use IMAP.
Our servers support both IMAPS and POPS, which are secure forms
of the IMAP and POP protocols. This uses SSL to encrypt
your username and password on its way to the server. Most
modern clients support this and its strongly suggested that
you enable it on your client. If you do not, your password
will travel over the internet in clearly readable text, making
it possible for a malevolent user to assume your identity and
steal your files or send e-mails under your name, among other
things.
For the more advanced users who want to use Pine or Mutt to
read their mail via IMAP, you can address your IMAP INBOX by
specifying it as:
pine: {imap.cs.iastate.edu/norsh/novalidate-cert/user=username}
mutt: imaps://username@imap.cs.iastate.edu/INBOX
Lastly, we also have a web based e-mail client. Just
point your browser to webmail.cs.iastate.edu
and use your Computer Science username and password to login.
This is, in fact, a web based IMAP client.
Using ~/.rhosts is felt to be a substantial security
problem, and is not enabled on the departmental machines.
Also, rlogin and rcp have been disabled on our machines in favor
of ssh and scp. We strongly suggest you use ssh instead.
Yes, but it is not quite as simple as it used to be.
The IT system requires Kerberos authentication for its FTP and
Telnet services now.
If you are using Linux, you may follow this excellent tutorial
here, skipping past the installation steps:
http://www.public.iastate.edu/~kula/redhat.html.
If you are using Windows, there is a great tutorial describing
the FTP process here:
http://support.cs.iastate.edu/how_to/ftp/how-to-ftp.htm.
To use telnet on a Windows machine to access AIT, you can find
it through the following menus: All Programs -> IASTATE
Software -> Hummingbird Connectivity V8.0 -> HostExplorer
-> Telnet.
Yes, but only if you tunnel X through an ssh connection.
If you are in an office, it is possible without ssh, just ftp
your Computer Science ~/.Xauthority file over to your IT account
and set your DISPLAY variable to your local workstation.
Note that if you ssh between Computer Science Linux workstations
this will be taken care for you automatically.
To find out simply type "quota" at a Linux command prompt:
pyrite:~> quota
Disk quotas for user username (uid xxxx):
Filesystem blocks quota limit grace files quota limit grace
odin:/home/ugrad1
9448 50000 55000 968 3000 5000
This shows you the number of blocks (disk space) and the number
of files you are using. Note that you have quotas on both
the amount of disk space and the number of files
in your home directory. If your blocks/files go over the
number listed under quota, you will have until the shown grace
period to bring your usage down to under your quota or else
further writing to your home directory will not be possible.
The number given under limit shows the absolute maximum blocks/files
you can have in any case. Further information can be found
under the manpage for quota(1).
When looking for things to remove when exceeding your quota,
a common culprit is the cache left over from internet browsers
such as netscape/mozilla. These are under the directories
~/.netscape and ~/.mozzilla respectively. A useful tool
for further investigation of your disk usage is the du command.
Check out the manpage for du(1) for further information on this
command.
If you feel your current Computer Science course(s) requires
more disk quota then you are currently allocated, please have
your instructor request more on your behalf by having her/him
send an e-mail to ssg@cs.iastate.edu.
Current disk quotas are grouped by classification as follows:
| Non-Computer Science Majors |
100 mb |
| Undergraduate Computer Science Majors |
200 mb |
| Graduate Computer Science Majors |
400 mb |
The easiest way is to use the mtools package. Use "mformat"
to format your disk with a dos filesystem, then use "mcopy",
"mdelete", and the other m-commands to move files around.
Man mtools for further details.
The department has laser printer access for all Computer
Science accounts.
The printers accessible by all students/staff are:
| hplj9050 |
high output postscript laser printer
located in Pearson 0108 |
| hplj8150 |
high output postscript laser printer
located in Pearson 0105 |
| hplj5500 |
color postscript laser printer located
in Pearson 0105 |
| hplj5 |
postscript laser printer located in
Pearson 0141 |
| hplj8150-213 |
postscript laser printer located in
Atanasoff B01 |
The printers accessible only by staff are:
| hplj9500 |
high output color postscript laser printer
located in Atanasoff 226 |
The commmand for printing under Unix is lpr. You use it in
this fashion:
lpr -Phplj8150 myfile.ps
This would print the file named myfile.ps on the printer hplj8150.
The -P flag determines the printer you want to use. Note that
all postscript printers only accept postscript files.
If you are printing from a Windows machine this conversion is
handled automatically. If, however, you were printing
from a Linux machine and wanted to print a text file you would
need to use enscript, a2ps, or a similar program.
We do not support the use of 3rd party papers or transparencies
in the public printers. If damage occurs to the printers
through the use of these items the student will be held accountable
for hardware repair and labor charges.
For further help and related commands please check the man
page for lpr(1) and lpq(1).
Simply create a directory named WWW in your home directory
(must be all caps) and make a file in that directory named homepage.html.
You can create your home page in this file. The WWW directory
should be mode 755 (chmod 755 ~/WWW), ~/WWW/homepage.html
should be mode 644 (chmod 644 ~/WWW/homepage.html), and your home
directory should have world execute permission (chmod o+x ~/).
Graduate students/staff can get their web page added to the department's
web personnel directory by sending a request to webmaster@cs.iastate.edu.
There is no longer a global directory for undergraduate students.
Please note that the webmaster is not a member of the Systems
Support Group and further questions about WWW services for the
Department of Computer Science should be directed towards:
webmaster@cs.iastate.edu.
The system will set your default PATH before it accesses your
personal startup files. If you do not include a path then
the default will be used, which should include all the basic
tools you need. If you wish to modify your PATH, you can
put a statement like this in your ~/.bashrc file:
export PATH=$PATH:/my/extra/path
which will append /my/extra/path to the end of the system default
path.
SSH has two modes that you can use, varying in the
degree of security they provide. The first mode is to use
your regular account password to connect. This mode does
not require any additional setup beyond the initial installation
of a ssh client. Simply connect via the ssh client to your
destination and enter your Computer Science username and password.
If you are not sure which machines you can connect to please see
this entry within this FAQ: Once I register, which
machines do I have remote access to?
The second mode available via SSH is through the use of a RSA/DSA
key pair. This provides greatly enhanced security and
allows you to use more advanced features such as a ~/.shosts
file. In order to utilize this mode you are required to
create your RSA/DSA keys first. Note that for this example
we will be creating the RSA key only. If you wish to create
your DSA key the procedure is the same just substitute dsa for
rsa in the example. If you wish to know the differences
between RSA and DSA there are many papers on the subject available
on the internet, such as this one: Techniques
in Cryptography. Note that you should not create your
keys if you are connected via an unsecured connection such as
telnet. You should either be connecting via ssh using
your regular Computer Science password or you should be physically
at the machine where you are creating your keys.
Here are the steps in creating your RSA key:
1) At a command line prompt enter the following command:
ssh-keygen -t rsa
2) Press enter when the program asks where to save the key
(this accepts the default location).
3) At the "enter passphrase" prompt enter a NEW password
that you are not using anywhere else. Using your regular
Computer Science password is NOT recommended. This password
has no restrictions as to length or complexity. Many people
use phrases instead of a single word for their passphrase.
4) Now enter your ~/.ssh directory with the following command:
cd ~/.ssh
and copy your new public key into your authorized keys file.
This file is very important as it permits the
key you just created to login to your account:
cp id_rsa.pub authorized_keys
Logging in from a Linux machine using SSH:
The "ssh" command (no quotes) will allow you to connect
to a remote host over an encrypted connection. Also, any
X11 applications will also be encrypted if they are started
from the new SSH login. For example, to securely login
to host pyrite.cs.iastate.edu one would enter:
ssh pyrite.cs.iastate.edu
Depending on whether you have setup your RSA/DSA keys, you
may be asked for your passphrase or your normal Unix password.
Logging in from a Windows machine using SSH:
There are many excellent free ssh clients available for the
Windows platform. Some of them include Tera
Term, PuTTY,
and the client available at http://www.sitelicensed.iastate.edu.
All of these are excellent clients that will allow you to connect
securely to the Computer Science systems. All Windows
machines in the student labs have the ssh.com client installed
on them.
If you get disconnected ungracefully, or just want to check
to see what you have running, you can always just do:
ps auxw | fgrep username
substituting your Computer Science username in place of the
word "username". The numbers under the PID column
are the process ID's. If you wish to kill a process, you
can try "kill -1 PID". If that doesn't work, try
"kill -9 PID", substituting the PID of the process
you wish to kill.
Any unattended or long-running background jobs (or
any jobs that consume "significant" CPU time) should NOT
be run on pyrite.cs.iastate.edu. They may be run on any
machine internal to the student labs (which are also accessible
remotely).
All unattended background jobs should be nice'd (just add "nice"
to your command line - e.g. if you wanted to run a program called
"monster" in the background, and it was going to run for a long
time, you might say "nice monster&". Any jobs found not
niced (and causing problems) may be reniced to the lowest possible
priority or killed (for "repeat offenders").
Any IRC bots, non-academic HTTPd's, or similar daemon-type processes
are candidates to be killed with no warning at any time. If you
have questions about what is or is not ok to run, please contact
ssg@cs.iastate.edu. We
don't spend all day looking at process lists to find something
to kill, but if something gets noticed for whatever reason, it
may get reniced or killed.
Please first be sure you don't have a backup of the
file, and be sure the file is "worth restoring" from tape - i.e.
it can't easily be reconstructed. Emacs is fond of leaving
backup files laying around, so please be sure to check for them
first or if you are a vi user try "vi -r" (man vi for
info). Restoring files from tape isn't technically challenging,
but it does take a fairly large amount of time due to the linear
nature of tape, so we'd rather not spend the bulk of our day doing
file restores unless the data is fairly important.
If you still want to ask to have a file restored after reading
this, send an e-mail to
ssg@cs.iastate.edu with a detailed account of the files exact
path and your best estimate of the last time you modified the
file. If it has been longer then a week since you modified
the file please state that instead of your estimate. Please
allow 24 hours for all tape restore requests to be completed.
We currently do backups every night of the week just after
midnight. Backups are kept for one month before the tapes
are recycled.
The main SSG (System Support Group) offices are located
in 0125 Pearson Hall, and are typically staffed from 8 AM until
5 PM. If the door is unlocked, please come in. We
may not always hear you knocking. If the door is locked,
it's probably the case that everybody has stepped out for a moment
or we are in the middle of a meeting; please try again in a few
minutes.
If your question can be answered in e-mail, you may send mail
to ssg@cs.iastate.edu
and we will respond as soon as we can.
The Systems Support Group consists of 3 full-time positions
and four student employees.
The individual email addresses of the Systems Support Group
full-time members are:
All student employees are located in 0125 Pearson Hall.
If you are a graduate student or undergraduate student
with a single or double major of Computer Science your account
will be active until you leave the department or university (ie.
graduation or changing majors). Visiting instructor/scholar
accounts will remain as long as they are involved with the department,
or as until deemed necessary by a faculty member. If you
are not a Computer Science major and have an account due to a
class you are taking, then your account will be deactivated at
midnight a week after the last day of the semester, typically
the following Friday after finals week. If you are going
to be eligible for a Computer Science account in a following semester,
you will have the opportunity to create a new account during
the first week of classes, your old account will not be reactivated.
Please be sure to archive any files you want to save (to a floppy,
CD-R, or your home machine for example) before your
account is deactivated; your files may not be recoverable afterwards.
Extensions to postpone the deactivation of an account are
possible. If you are seeking an extension, please fill
out the form: Computer
Account Extension. Note that extensions usually require
the sponsorship of an instructor or faculty member.
You have several available options; some of the more
common are backing up to floppy disks, burning to a CD-R, or creating
a tar archive and FTPing it to another account. All Linux
and Windows workstations have floppy drives available for your
use. For Linux workstations you can use the mtools package
(see How do I use
floppies on the Linux workstations?) for accessing the floppy.
Most of the newer Windows machines have CD-R burners installed
as well as burning software. Backing up your files is as
simple as dragging your files from your home directory (usually
mounted as the H: drive) into the burning program and writing
them to the CD-R.
If FTPing your files is your choice, use the "tar" command
on a Linux workstation to create an archive of the files you
wish to save. For example, issue the following command
to save the directories "Mail" and "homework" into a tar archive
called "myfiles.tar":
tar -cvf myfiles.tar Mail homework
To extract this archive on the remote machine after you have
transferred it, login and issue the command:
tar -xvf myfiles.tar
You may find it useful to use "compress" or "gzip" to reduce
the size of the archive before transferring. Please "man tar",
"man compress", and "man gzip" for more information.
To check your black & white laser printing quota, ssh to
a Linux machine (such as pyrite.cs.iastate.edu) and issue the
command:
laser
To check your color laser printer quota issue the command:
color-laser
The dot matrix line printers do not have a quota. Note
that your quota resets at the beginning of every month.
Current black & white laser quotas are grouped by classification
as follows:
| Non-Computer Science Majors |
75 printed sides |
| Undergraduate Computer Science Majors |
100 printed sides |
| Graduate Computer Science Majors |
325 printed sides |
Current color laser quotas are grouped by classification as
follows:
| Non-Computer Science Majors |
0 |
| Undergraduate Computer Science Majors |
10 printed sides |
| Graduate Computer Science Majors |
40 printed sides |
25 - How can I use FTP?
FTP access to the Department of Computer Science is available
through ftp.cs.iastate.edu.
You can connect to this server from anywhere on the internet.
Our other workstations and servers do not allow incoming FTP
connections. All FTP access must be done through ftp.cs.iastate.edu.
Connecting to the FTP server can be done with any FTP client.
However, if you are trying to connect from behind a NAT firewall
(sometimes called a cable/DSL router in retail stores), you
must use a client that supports passive mode FTP. Please
enable this option if available. Most modern FTP clients
will have this enabled by default as it will not effect your
connection if you are not behind a firewall and is nothing but
beneficial.
For secure access to the FTP server, SSL/TLS is supported.
This will encrypt your username and password as it travels over
the internet and also, optionally, encrypt all data sent to
and from the FTP server. Many modern FTP clients support
SSL/TLS connections including SmartFTP for Windows and LFTP
for Linux. Note that FTP connections tunneled through
SSH, such as sftp, are not supported. It is strongly suggested
that you enable SSL/TLS on your client. If you do not,
your username and password will travel over the internet in
clearly readable text, making it possible for a malevolent user
to assume your identity and steal your files or send e-mails
under your name, among other things.
The student labs in Pearson Hall are behind a NAT firewall
and thus connections to an FTP server requires the use of a
passive mode FTP client. On the Windows machines the client
SmartFTP is installed for this purpose. It is also possible
to use Internet Explorer in passive mode if the option is enabled
under the Advanced Internet Options menu. Note
that FTP connections to AIT are handled differently and are
discussed here: Can
I get at my IT files via FTP or Telnet?
On the Unix systems the command to use for a ftp client is
either "ncftp" or "lftp". The ncftp
client is very user friendly and most prefer it over the legacy
"ftp" command. To use it simply type "ncftp
-u username ftp.somewhere.com" substituting your username
for your account on ftp.somewhere.com. The lftp client
is more traditional and supports both passive mode and SSL/TLS
connections. To use it simply type "lftp -u username
ftp.somewhere.com" substituting your username for your
account on ftp.somewhere.com. Red Hat Linux Enterprise
has changed the legacy "ftp" command to primarily
support Kerberos now. It is strongly suggested you use
either "ncftp" or "lftp" for FTP connections
from the Unix systems to standard hosts, and use the "ftp"
command for Kerberized connections to AIT (see Can
I get at my IT files via FTP or Telnet?).
The SmartFTP client is freely available for download and we
highly suggest it for home use on a Windows machine. You
can download it at the SmartFTP
Home Site. It supports both passive mode and SSL connections
and is free for personal use. If you are looking for a
Unix client we suggest you try out LFTP,
which also supports these options.
Yes, you can get a free legal copy of various Microsoft products
including Windows XP and Windows 2003 Server. This software
is available to us through the MSDNAA
program and allows any student taking a Computer Science course,
as well as Computer Science staff, to be eligible for free software.
To acquire this software it is necessary to go to Pearson 0108
and use the machine labeled "Burning Station" to burn
the software onto CD-R media. It is the black machine
along the east wall and next to the scanner. The only
way to access this software is to be physically at the burning
station, it is not possible to access it from a remote location.
You may login to the burning station using your Computer Science
username and password. If you do not have a Computer Science
username and password you will need to register for one first
(see How
do I register for a Computer Science account and who is eligible?).
You must supply your own CD-R media, we do not supply it nor
do we have any for sale.
Once logged in you will find the images of the software CDs
in a folder named "Images" on the Desktop. Simply
browse to the image of the software you want, and double click
it to bring up the burning interface. Now just stick in
your CD-R blank, hit "Start Recording", and your software
will be completed within minutes.
Some software, such as Windows XP, will require you to obtain
product activation keys in order to use it. For this,
you must go to the ELMS for MSDNAA site located at:
http://msdn02.e-academy.com/iastate_cs. You must now
register on this site if you have not done so already.
This site is external to the University and is run by Microsoft.
For the username field, while registering, use the middle nine
digits on your University ID, the same ones you used to first
register your Computer Science account.
Once you are registered and have logged in, click the software
tab under the ELMS banner then select the product you need the
activation key for in the drop down menu and click the "Go"
button. Now click the "Add to Cart" button and
read the Microsoft software agreement. If you accept the terms,
click the "I accept" button and then the "Check
Out" button. Verify the fields on the next page and
then click "Next". Now click on the product
name that was in your cart. You will see the product key
you need in the "Serial Number" field on this page.
Note that it is not possible to download the software from
this website! You must go to the burning station in
Pearson 0108 to burn the software, you can only obtain your
product keys here. If you forget a key you can click the
"My Software" bar on the left side of the window,
click Download on the product of your missing key, and view
your previously obtained product key.
A listing of the software currently available for burning is
available at:
http://support.cs.iastate.edu/msdnaasw.html
Revision: 0823200601
