How do I setup wireless on my laptop?
This is the basic technical information for all devices:NU’s wireless network supports 802.11b/g/n.
Settings required to connect to wireless are consistent among devices:
- Network Name (SSID): Northwestern
- Network Type: WPA2 Enterprise
- Encryption Type: AES
- Authentication: 802.1X
- User Name: (your university NetID)
- Password: (your NetID Password)
- EAP Type: PEAP
- Inner Authentication Method: MSCHAP v2
- Security Certificate: VeriSign Class 3 Secure Server CA - G2
For for more specific instructions on how to install wireless depending on your machine, OS, etc., consult the NU pages about wireless networking.
How do I check may department email from home?
In order to connect to the department from home you need a third party Internet provider.For some services you may need also VPN (Virtual Private Networking):
http://www.it.northwestern.edu/oncampus/vpn/One simple way to check your email on our system from home is to use webmail:
https://secure.math.northwestern.edu/mathmail/That link takes you to your email in your "public" account on our system. If you have a "private" machine in your office with a separate email account, then you may request to have webmail installed on your machine. Contact your system administrator about it. [Update: we stopped setting up machines to receive and/or send mail directly, so new machines do not have separate email accounts.]
Also, you can set up an email reader on your home computer to access our email server using POP, or IMAP over SSL (preferred). The details of how to configure your mail reader depends on the particular program you are using, but these are some of the technical details commonly needed:
While connecting to read or send email accept the certificates and authenticate with your Math comp system username and password - you may have to authenticate twice, once for reading your email, and again for sending email.
Incoming mail server: imap.math.northwestern.edu Port for incoming mail: 110 (POP), or 993 (IMAP over SSL), or 143 (IMAP) with STARTTLS. On Android select "SSL (Accept all certificates)" Outgoing mail server: mailhost.math.northwestern.edu Port for outgoing mail: 587, and select secure connection with STARTTLS or TLS (but not SSL/TLS). On Android select "TLS (Accept all certificates)"
How do I change my NetID password?
Click the following link:http://www.it.northwestern.edu/netid/
Remember that your NetID password is the password that you need to use with your university NetID in order to access various university services. Note that your university computer account is independent from your department computer account.
How do I produce PDF files?
It depends on the type of source.- In order to convert a PostScript file to PDF use
the epstopdf command
epstopdf filename.psor the pstill commandpstill -o filename.pdf filename.ps - In order to convert a DVI file to PDF, use the dvipdfm
command
dvipdfm filename.dvi - Alternatively, in order to convert a DVI file to PDF, first
produce a PostScript file with the
dvips command including the -Ppdf flag
dvips -Ppdf filename.dvi -o filename.psthen convert the PostScript file to PDF with epstopdf or pstill as explained above. - In order to produce PDF directly from a tex or
latex source, use the pdftex or
pdflatex command:
pdftex filename.texorpdflatex filename.tex
How do I set up a vacation message?
On your home directory, type "vacation". Write your vacation message. Save and exit. That will create a file called ".vacation.msg" with your vacation message. The vacation program also creates a file called ".forward" on your home directory. Remove it (or rename it if you prefer so):
rm ~/.forward
(We do not want to use that file, to avoid "replying" to spam.)
Then include the following rule in your .procmailrc file
(after the antispam rules!):
:0c |/usr/local/bin/vacation usernamewhere "username" is your username.
Ask for assistance from your system administrator if you have any problems.
To disable the vacation mechanism just comment out those lines:
#:0c #|/usr/local/bin/vacation username
The vacation program does not work on my Linux machine. How can I set it up so that it replies automatically to incoming messages while I am absent?
Do the following on your home directory:
- Create a file called "vacation.msg" with your vacation message.
- Create (or edit if it already exists) a file called
".procmailrc" with the following content (if the file already
exists, just add the "vacation" segment). Replace the word
"username" with your actual username.
PATH=/bin:/usr/bin:/usr/local/bin MAILDIR=$HOME/Mail # you'd better make sure it exists SPOOLDIR=/var/spool/mail DEFAULT=$SPOOLDIR/$LOGNAME NSMAIL=$HOME/nsmail PINEMAIL=$HOME/mail SENDMAIL=/usr/sbin/sendmail LINEBUF=16384 #------------- begin vacation segment ------------------- SHELL=/bin/sh :0 hc * !^FROM_DAEMON * !^X-Loop: username@math.northwestern.edu | (formail -rA"Precedence: junk" \ -A"X-Loop: username@math.northwestern.edu" ; \ cat $HOME/vacation.msg \ )| $SENDMAIL -oi -t #------------- end vacation segment ---------------------
- If you wish to disable the vacation feature after your return, rename the ".procmail" file, or remove (or comment out) the vacation segment.
Click here for a sample of a .procmailrc file that you can use for emulating the vacation program.
I have a hardcopy of a document and I want to make an electronic version of it. How do I do it?
There are basically two ways. The easiest and fastest one is to use our photocopier, which also works as a scanner. It will email you the scanned document as an attached PDF file.The main problem with the photocopier is that it scans entire pages, so if you only want to scan a part of a page you may consider using our scanner. Make sure that each page is saved to a file in PDF format - i.e.: in tkscan select "Output to File" and "File Type: PDF". If you cannot save the page in PDF format, save it in any image format (say PNM) and convert it later into PDF:
convert file.pnm file.pdf
Once you have scanned all the
pages of the document you will have a number of PDF files, one for
each page. The final step is to merge
them into a single PDF document, as explained in the next
paragraph.
How do I merge several PostScript/PDF documents into a single PostScript/PDF document?
For instance, in order to merge foo1.ps, foo2.pdf and foo3.ps into a single PDF document called foo.pdf use the following command:
gs -sDEVICE=pdfwrite -sOutputFile=foo.pdf -q -dNOPAUSE foo1.ps foo2.pdf foo3.ps quit.ps
A slightly different way of doing the same:
ghostscript -dNOPAUSE -sDEVICE=pdfwrite -dBATCH -sOutputFile=foo.pdf foo1.ps foo2.pdf foo3.ps
Same, but the output is now a PostScript file:
ghostscript -dNOPAUSE -sDEVICE=pswrite -dBATCH -sOutputFile=foo.ps foo1.ps foo2.pdf foo3.ps
The following command will merge all files named part*.ps into out.pdf:
mergeps2pdf part out
There are similar commands mergeps2ps, mergepdf2ps, and
mergepdf2pdf, intended to merge ps to ps, pdf to ps and pdf to pdf
respectively.
How do I select pages from a PDF file?
In order to extract pages n through m from a document infile.pdf and write them on a document called outfile.pdf, use the following command:
texexec --pdfselect --selection=n:m -result=outfile.pdf infile.pdf
How do I forward email automatically to another address leaving at the same time a copy of every message in my email account here?
NOTE: The use of a ".forward" file is now strongly discouraged to avoid forwarding unfiltered spam [Update: the .forward mechanism is now disabled on our mail server, .forward files won't work]. Use the method described below instead.Assume that the forwarding address is "j-doe@another.site.ws". Hopefully you have a .procmailrc file on your directory, at least for the purpose of filtering spam - if you don't have it you will need to create it. Then, insert the following rule after the rules intended to filter spam:
:0c ! j-doe@another.site.wsRemark: The "c" after the "0" means that a copy of the incoming message will be generated (without it the message will be forwarded to the given address but no copy would be left here.) The exclamation mark "!" means "mail the message to the given address."
Note: If there is a risk that the forwarded email may bounce (causing a loop), use the following recipe instead:
:0c * !^FROM_DAEMON ! j-doe@another.site.ws
The following is a possible example of the content of a .procmailrc file with spam filtering followed by forwarding.
############################################################# PATH=/bin:/usr/bin:/usr/local/bin MAILDIR=$HOME/Mail #you'd better make sure it exists SPOOLDIR=/var/spool/mail DEFAULT=$SPOOLDIR/$LOGNAME LOGFILE=$MAILDIR/from #recommended LOGABSTRACT=all LINEBUF=16384 ###################### SPAMASSASSIN ######################### :0fw: spamc.lock | spamc :0 * ^X-Spam-Flag: YES caughtspam ####################### forwarding ########################## :0c # (remove the c if you do not want to keep copy of incoming email here) ! j-doe@another.site.ws #############################################################
How do I ssh to other machines without having to type my passphrase every time?
You can use an "authentication agent" for that. For instance, type the following in a terminal:
ssh-agent gnome-terminal &
This starts a new window (in fact a gnome terminal) that will act as
an authentication agent. Inside that window type
ssh-add
You will be prompted for your passphrase. Write it. That adds your
private key to the authentication agent. Now you can open other
windows by typing (inside the window acting as authentication agent)
gnome-terminal &
The new windows opened that way will serve also as authentication
agents with your private key already added. Now you can ssh from
inside any of those windows without having to retype your passphrase.
The technical details are in the manual page of ssh-agent (man ssh-agent).
I have a file ending in ".gz". How do I open it?
That is a compressed file. Uncompress it with gunzip
gunzip filename.gz
That produces an uncompressed file with the same name but without the
".gz".
How do I avoid getting spam?
There is no good way to get rid of all spam messages received by email, but a program called spamassassin makes a good job keeping somewhat under control how much spam you actually see. That program is running permanently on our server, so it is available for all users with an account on our public computers. In order to take advantage of it, create on your home directory a file called .procmailrc with the following content (if you already have a .procmailrc file, just add the lines for SPAMASSASSIN):PATH=/bin:/usr/bin:/usr/local/bin MAILDIR=$HOME/Mail #you'd better make sure it exists SPOOLDIR=/var/spool/mail DEFAULT=$SPOOLDIR/$LOGNAME LOGFILE=$MAILDIR/from #recommended LOGABSTRACT=all LINEBUF=16384 ###################### SPAMASSASSIN ######################### :0fw: spamc.lock | spamc :0 * ^X-Spam-Flag: YES caughtspam #############################################################After doing that all messages determined to probably be spam by the spamassassin program will be placed in a file called "caughtspam" in the Mail subdirectory of your home directory. Make sure to look at that file periodically to check for false positives (messages wrongly classified as spam by spamassassin).
When I try to ssh to host X, I get an error message saying that the host key has changed and the login fails.
Typically the error message looks like this:@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY! Someone could be eavesdropping on you right now (man-in-the-middle attack)! It is also possible that the RSA host key has just been changed. The fingerprint for the RSA key sent by the remote host is 4b:c7:84:51:cd:12:27:cb:f3:bd:6e:98:9a:e3:cb:ae. Please contact your system administrator. Add correct host key in /rhome/username/.ssh/known_hosts2 to get rid of this message. Offending key in /rhome/username/.ssh/known_hosts2:1 RSA host key for hostname has changed and you have requested strict checking.Solution: The problem can be solved with some editing of the files known_hosts (and possibly known_hosts2,) but the simplest thing is just to remove them:
rm ~/.ssh/known_hosts ~/.ssh/known_hosts2They will be recreated later with the correct host keys.
What machines can I use?
If you have an account in the Math computer system you can use the Linux machines in Lunt B10.Our "public" machines are:
If you have an office with a Linux machine and you cannot login probably it is private. Depending on various circumstances you may be eligible to get a separate "private" account in it. Contact the system administrator to find out.
How do I access JSTOR remotely?
On the Math Dept Web page click "Resources", then go to the second listing "Math library" under the listing "Northwestern Resources", then to "Electronic Journals in Math and Statistics", then to the journal you are looking for. One needs an NU ID to actually access the journal.
How do I make a password protected web page?
First make sure that the "htpasswd" command is available (the apache daemon "httpd" must be installed on your machine.)which htpasswdThat should return "/usr/bin/htpasswd". If it returns something like "/usr/bin/which: no htpasswd in ... " that means that the command is not available, and the rest of the process can not be carried out - in that case ask your system administrator to install the apache webserver on your machine (but you may want to leave it "off" anyway).
Then do the following.
- Create the directory that will contain the passwords (must be outside
your web home directory for security reasons!)
cd /rhome/username mkdir passwd
where "/rhome/username" means the full path of your "public" home directory. - Create the password file and assign a password to the first user
(called "john_doe" here):
htpasswd -c passwd/passwords john_doe
If you wish, you may add more users and passwords with the same command but without the "-c" flag:htpasswd passwd/passwords jane_doe
- Create the directory that will contain the protected pages
cd public_html mkdir restricted cd restricted
- Create a ".htaccess" file inside that directory (the one
that will contain the protected pages) with the appropriate access
information:
AuthType Basic AuthName "Restricted Files" AuthUserFile /rhome/username/passwd/passwords require user john_doe
where "/rhome/username" must be replaced with the full path of your "public" home directory. - Create a basic "index.html" file inside the protected
directory and test it by trying to access it at the URL
http://www.math.northwestern.edu/~username/protected/index.html
where "username" is your system username. You should be prompted for a username and password. You may use any username you have entered in the password file ("john_doe", or "jane_doe", or whatever), and the corresponding password for that username.
How do I write my email address as an image file?
In order to avoid email harvesters used by spammers, some users may choose to include their email addresses on their web pages as an image instead of plain tex. To produce one such image file with an address "username@math.northwestern.edu" use the following command:convert -size 200x15 xc:white -pointsize 12 -draw "text 5,10 username@math.northwestern.edu" emailadd.jpgYou should get something that looks like this:
If the resulting image does not look quite right you may need to change the options and flags of the command (type man convert for additional information on the convert command.)
How do I train spamassassin?
Although the rules used by spamassassin are effective in catching a great amount of spam, the ability of spammers to get around those rules and the specific characteristics of mail received by a given user (and his/her preferences) may require some changes in those rules with time. In order to accomplish that, do the following:- Classify your mail into folders which only contain spam or non-spam ("ham"), but not both. For instance assume that you have saved spam messages in a folder called "junk", and keep ham (good email) in a folder called "good_mail".
- Run sa-learn once per folder, telling sa-learn whether to
consider that folders' contents to be spam or ham:
sa-learn --spam --mbox junk sa-learn --ham --mbox good_mailYou may use more than one folder of each ham and spam. Just run sa-learn similarly for each folder. - Make sure that you train spamassassin with both ham and spam. If you only train with spam the filter will become biased towards spam.
- You also want to clear all spam out of your inbox, and file that:
sa-learn --ham --mbox /var/spool/mail/usernamewhere "username" is your username, orsa-learn --ham --mbox mboxdepending on where you store your incoming messages. - If you'd like to see what's currently in the database, do:
sa-learn --dump magicYou will get something like this:0.000 0 3 0 non-token data: bayes db version 0.000 0 147531 0 non-token data: nspam 0.000 0 102387 0 non-token data: nham 0.000 0 138118 0 non-token data: ntokens 0.000 0 1164052510 0 non-token data: oldest atime 0.000 0 1165431546 0 non-token data: newest atime 0.000 0 1165429022 0 non-token data: last journal sync atime 0.000 0 1165234855 0 non-token data: last expiry atime 0.000 0 345600 0 non-token data: last expire atime delta 0.000 0 265307 0 non-token data: last expire reduction count
nspam and nham are the number of spam and ham messages that spamassassin has learned from.
How do I convert a PNM file into a PDF file (or an ABC file into an XYZ file)?
Each conversion may require a different converter, but the convert command often works:
convert filename.pnm filename.pdf
convert filename.abc filename.xyz
I have tried to send messages to people with hotmail.com addresses, it doesn't bounce, but doesn't arrive, or goes directly to their junk folder.
Most likely Hotmail spam filters are misclassifying your email as spam. (This seems to be a recurrent problem in sending email to hotmail accounts, we very rarely have problems sending email to other Internet providers such a gmail, yahoo, other universities, etc.)The best way to prevent your email from being classified as spam by hotmail is that the receiver includes your email address, or better yet, the "math.northwestern.edu" domain, in his/her hotmail safelist. These are the instructions provided by Hotmail to that effect:
Q. I received an e-mail in my Junk E-Mail Folder that wasn't Junk. What can I do?
A. To help prevent messages from specific senders from being evaluated as junk e-mail, you can add the senders to your safelist.
If you're using MSN Hotmail:
1. Click Options.
2. On the left side of the page, click Mail, and then click Junk
E-Mail Protection.
3. Click Safe List.
4. Type an address or domain (a domain is the part of an e-mail
address that follows the @ sign) from which you always want to receive
messages, and then click Add.
If you're using Windows Live Hotmail:
1. Click Options.
2. Click Allowed and Blocked Senders under Junk e-mail
3. Click Allowed senders.
4. Type an address or domain (a domain is the part of an e-mail
address that follows the @ sign) from which you always want to receive
messages, and then click Add to List.
See: http://postmaster.hotmail.com/FAQ.aspx
How do I add a department printer on my Windows machine (or wireless laptop, etc.)
Look here
When trying to connect to the department webmail, or some other login web page, I get a warning about an "invalid security certificate".
That happens because we use a (free) self-signed certificate. In order to avoid getting that warning every time you visit that page you can add our certificate as a security exception. The details of how to do it depends on the browser, these are the steps for Firefox 3.0:
- After you get the warning about an invalid security certificate click "Ok".
- Click the link "Or you can add an exception..."
- Click the button "Add exception..."
- Click the button "Get Certificate".
- Click the button "Confirm Security Exception".
After that the security certificate is added as an exception and you should not get the warning anymore.
I have received an email message with a "winmail.dat" attachment that I cannot open, what should I do?
That usually happens for mail sent by Microsoft Outlook users to non Microsoft Outlook users. This is better approached as a misconfiguration problem on the sender's side, so the first solution is to instruct the sender to configure their Microsoft Outlook NOT to send winmail.dat attachments - see here.If that does not work there are utilities that the receiver can use to decode winmail.dat attachments, but they should be used with caution because of potential security problems - for instance NEVER submit a document with sensitive information to an online site claiming to decode winmail.dat attachments for you.