Setup Ubuntu/Linux/Gnu frontends

(deprecated pre 2012, see current CSCF Ubuntu Setup Information)

A description of what a frontend is

Strictly speaking, frontends really should mean XDMCP/RDP enabled thin clients which allows them to connect to X and RDP servers.

In the core region we provide fe-linux.student.cs (round robin DNS name for a cluster of hosts) in the student region the DNS round robin name of fe-linux.student.cs is provided.

Ubuntu Based Student Frontends

The student frontends can be accessed via the name fe-linux.student.cs. On a thin client DNS round-robin is used to pick a particular representative of this name.

As of September 2008, the hosts representing fe-linux.student.cs run Hardy/Herron (8.04) Ubuntu on AMD64 architecture.

As for the vendor package configuration, the setup is designed to discourage building software. In particular the display manager is gdm and the two desktops are KDE and Gnome along with failsafe choices which should only be invoked if a user needs minimail access to fix something that is preventing them from logging into either GNOME or KDE.

The systems were transformed to using Hardy by first setting up mef-fe12.student.cs and then using systemimager to install the other hosts. Most files that needed changing are RCSed and can be found by typing locate ,v except for /etc/gconf/gconf.xml.mandatory/%gconf-tree.xml which was generated by running gconf-editor and changing certain parameters to mandatory (NOTE. This file is human readable and can be copied to other hosts which would save you running gconf-editor on the host, however make sure the version of Ubuntu coincides). As to why this file was created, it was edited so that a non-priviledged user could not shutdown, or hibernate the machine upon logging out of their session.

Another key change to be aware of is /etc/X11/Xsession.options was to disable user Xsession and Xresourcs files from being used as this can cause login difficulties (see below for more details).

Core Region Ubuntu Based Servers

In the core region we provide fully functional desktops, that is, development environments in addition to the usual desktop environment that is present in the student region.

Software Installed

Management of /etc/passwd, /etc/shadow, and /etc/group

The authentication method proceeds by first trying Kerberos via the Active Directory server and then Unix passwd/shadow. The files themselves are managed via the Xhier setpw package. To convert the frontends to not using setpw read convert to AD.

.xsession and GDM/KDM chooser

/etc/X11/Xsession.options should have the following entries:

no-allow-user-resources
no-allow-user-xsession
Otherwise, the {CS,MF}CF default .xsession can cause fatal errors, as it assumes they are logging into a Solaris and to be safe we also prevent a user's Xresources file from being processed.

The chooser, GDM or KDM, runs configuration files located in /etc/X11/xsession.d. These can potentially interact with xhierisms such as UbuntuXhierHowto#GDM. Specifically, xhiered the {CS,MF}CF version of csh will cause login warnings: "Xsession: unable to launch "noglob" X session --- "noglob" not found; falling back to default session." ( This does not seem to be an issue with the Hardy based systems as no local edits were made).

Unwanted Update Icon

As users logging into the server via XDCMP don't have permissions to update packages we want to remove it. The icon is provided by the package update-notifier. Removing this package gets rid of the icon.

Questions and Answers

There is a FAQ for consultants about the student front-end machines, located at MEFUbuntuFrontendFAQ
Topic revision: r39 - 2014-09-19 - DaveGawley
 
This site is powered by the TWiki collaboration platform Powered by PerlCopyright © 2008-2019 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback