# Mathematics Computerlab

The computerlab is a central facility of the Faculty of Mathematics. It provides the whole faculty with computers and computing services, including the maintenance of the underlying server infrastructure. At present, we administer some 300 clients and 50 servers, and run important services like the faculty website.

# News

## 07. 05. 2019 Upgrade of webmail

With the new release, an experimental mobile-skin is now available, which simplifies its use on mobile phones considerably. Some features may not yet work under this skin, such as setting filters, but these are still accessible under the normal skin.

## 15. 9. 2018 Upgrade of all linux clients

On 15 September 2018, all linux clients of the faculty have been upgraded to 18.04 LTS ("Bionic"). Please note the following changes.

### Choice of the desktop

We continue to offer the desktops Xfce4 (default), Gnome Flashback, Gnome 3 and "user defined". Unfortunately, the computers no longer remember the preferences for each user, but only the last used desktop on that computer. For computers with a single user, this is no problem, but on computers with several users (computer pool, tutor's offices), you have to choose your desired desktop before each login. There is an icon (the left-most one of the icon group on the top right of the login screen) which indicates the current choice.

### /var/tmp becomes /var/data

The dirctory /var/tmp on the local disk is now mounted under the new path /var/data. The data are preserved under this operation. /var/tmp will still exist (with much less space), and will initially be empty. If you have links to /var/tmp, or scripts which access /var/tmp, you have to adapt these.

/var/data can be used for large data (local data is accessed much faster than via the network), such as for postprocessing of simulation data, or for compiling large program packages, or for data which can easily recovered from the net (downloads, sync folders of cloud storage).

### Firefox ESR no longer provided

With very many pages, Firefox ESR does not work well, and is no longer provided. Please use the standard firefox instead. If you used Firefox ESR before, and want to migrate stored bookmarks and passwords, you can proceed as follows:

1. Start firefox from the command line with the option -ProfileManager
2. In the profile manager, create a new profile and start firefox with it
3. Stop firefox again
4. Copy the contents of the old Firefox ESR profile folder in ~/.mozilla/firefox-esr/ to the newly created profile folder located in ~/.mozilla/firefox/
5. After that, you can start firefox again normally.

## 20. 8. 2016 Upgrade of linux clients

On 20. August 2016, all linux clients of the faculty were upgraded to Ubuntu 16.04 LTS ("Xenial").

## 14. 6. 2016 Parameter Changes File Server

On 14. 6. 2016, some parameter changes on the HRZ-Filer (delivering the user homes) were made. These are necessary for compatibility reasons with other applications. These changes have the undesirable side effect, that ALSs of newly creates files and directories are no longer inherited from the parent directory. Instead, they must be set explicitly, as described here.

## 11. 9. 2015 Upgrade of file server

On Friday, 11 September, the Linux home directories and the file system /vol/tmp have been migrated to a new file server ("Filer"). Due to the migration, there will  be some changes in the behaviour of the file server, regarding file names, snapshots, /vol/tmp, and ACLs. Please read the following attentively, in order to avoid any bad surprises.

### File names

On the new Filer, all names of files and directories must be UTF-8 encoded. Files with differently encoded names cannot be stored. We use UTF-8 encoding already for many years. Old files with differently encoded names have already been converted. However, if you bring files from external sources, some attention is required, especially when unpacking zip- or tar-archives. Files with wrongly encoded names cannot be extracted (a warning is displayed). In order not to lose any files in such cases, you have to unpack the archive in a local directory (such as /var/tmp/<loginname>/). There, you can convert all names in a directory tree as necessary, with the command

convmv -f iso-8859-15 -t utf-8 -r --notest <directory>

Afterwards, the files can be copied to the home directory on the Filer.

### Snapshots

On the new Filer, snapshots will be made in regular intervals, which save the state of the file system at the corresponding point in time.  If you have accidentally deleted a file or directory subtree, or want to return to a previous version, you can simply take a copy of the file or subtree from one of those snapshots. There are several snapshot series (hourly, n-times-daily, daily, weekly, monthly) with different life times. These can be found in the hidden subdirectory .snapshot, which exists in every directory. Beware: the directory .snapshot is very hidden: it is not listed by a file manager nor with the command ls -a.  You have to access it explicitly with ls .snapshot or cd .snapshot, or enter it explicitly in the file manager.

### /vol/tmp

The file system /vol/tmp will also be migrated to the new Filer. At the same time, it is renamed to /vol/data (the old name was misleading). /vol/data is intended for archiving older projects and data which are no longer accessed regularly, as well as for simulation data which are too big for the home directory. Also for /vol/data,  snapshots und backups are available.

### ACLs

With ACLs one can precisely control the access of users to individual files and directories (see sharing folders). ACLs behave somewhat differently on the new Filer. On the old file server, as well as on the web server for the web pages (/vol/www/), the effective access rights correspong to the intersection of the rights from the ACLs and of the rights from the Unix file permissions for the group. Therefore, if ACLs are used, one usually sets the group permissions of all files to rwx, so that one can give access to other users via ACLs. On the new Filer, however, this is different: there, both Unix file permissions and ACLs directly give access to a file. Moreover, the two are not  independent of each other (changing one can change also the other, and vice versa).

In order not to open any security holes, existing ACLs will not automatically be migrated to the new Filer, and directory permissions for the group  user will be cancelled. If and where ACLs are required, you will have to set these up afresh. Please verify carefully that you really have set the rights you intended. If you need help, please write to root@math.uni-bielefeld.de.

## 24. 3. 2015 Upgrade of web server

On 23. March 2014 the faculty web server was upgraded to Apache 2.4, and on this occation was also switched to HTTPS throughout. Previously, HTTPS was possible, but not compulsory. It  turned out that some (user) web pages do not yet work completely correctly under HTTPS, usually due to "mixed content": an encrypted page embeds some unencrypted elements via HTTP, such as images and icons, but also CSS style sheets or JavaScript libraries. Whereas such images only lead to a warning sign in the address line of the browser, unencrypted style sheets or JavaScript libraries may be blocked by the browser (shield symbol in the asdress line of firefox), so that the page may not work properly. Please make sure that images and icons (including a favicon), style sheets and JavaScript libraries (such as MathJax) are always referenced with a https:// prefix (or leave out the server part of the URL, if it is a file on the same server). If everything works fine, a lock symbol is shown in the address line of the browser.

## 12. 9. 2014 Upgrade of linux clients

On 12. September 2014, all linux clients of the faculty were upgraded to Ubuntu 14.04 LTS ("Trusty").

## 12. 12. 2013 Migration to new web server

On 12. December 2013 the faculty web pages have been slightly restructured and moved to a new server. At the same time, the personal web pages of the users were moved to a new file system directly on the web server. Instead of  directory $HOME/WWW/, they now reside in /vol/www/user/$USER/, where $USER is the login name. All access rights remain the same, and in priciple, everything should work as before. However, should you include files from outside your former WWW directory, e.g. by using PHP or symbolic links, this will no longer work without modification. If you have problems correcting this, please write to root@math.uni-bielefeld.de. Note also that links from your home page to the faculty web pages may need to be adjusted, as many of the faculty web pages have obtained new addresses. Note: the directory /vol/www/user/$USER/ appears only when you access it. If you create a symbolic link,

ln -s /vol/www/user/\$USER/ ~/www

you can open it with the file browser (or enter it with cd ~/www).

## 23. 08. 2013 Reconfiguration of mail delivery

On the evening of 23. August 2013, a reconfiguration of the mail delivery procedure has taken place. Incoming e-mails are now delivered directly to the IMAP server.  If you previously had read your e-mail with pine or mutt from the ~/.inbox, you need to reconfigure your e-mail client so that it fetches incoming e-mail from the IMAP server. Please take note of our configuration hints. Users of Thunderbird and other IMAP e-mail clients are not cencerned.

Previous mail forwarding rules and filter rules as configured in ~/.forward or ~/.procmailrc do no longer work. As a replacement, you can conveniently configure equivalent rules on the IMAP server with the webmail interface. The mail forwarding rules have already been migrated to the IMAP server. In case of doubt, please check them in the webmail interface.

## 15. 01. 2013 Printing in Matlab

At the moment there are some problems when printing in Matlab. See the printer page of the MCL for more information.

## 13. 04. 2011 Problems with the Acroread Plugin for Firefox

The current version of the acroread plugin for firefox shows sometimes an empty or corrupted page. Often, a reload helps, but not always. If you are hit by the problem, you can configure firefox so that it uses an external viewer for PDF files, such as acroread (this way it works). Go to Edit->Preferences->Applications, and at the entry "PDF Document" (further down the list) select "Use Adobe Reader".