Can’t connect to my iMac after upgrading to OS X Lion

Since I upgraded my laptop to OS X Lion, I was not able to connect to my iMac (still running OS X Snow Leopard) anymore. Neither with Screen Sharing nor with direct file access. A quick search in the web couldn’t help me further so I decided to investigate in the issue by myself. The first starting point was to look into the Console and see if there where any error logged while trying to connect to the iMac.

The following error occurred repeatedly in the file. Another search showed me the sources of mDNS but that wouldn’t help me out on that topic.

4/27/12 5:15:09.659 PM mDNSResponder: CacheRecordRmv ERROR!!: How can CurrentAnswers already be zero for 00007F9843836290 _kerberos._udp.MYDOMAIN.LOCAL. (SRV) DNSServer <>:0

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Funktionsgraphen zeichnen

Vor einiger Zeit habe ich einige Programme und Webseiten zum Zeichnen von Funktionsgraphen gesucht und getestet. Heute möchte ich euch meine beiden “Testsieger” präsentieren.

Absoluter Favorit, leider aber nur auf dem Mac anwendbar: Grapher. Mit Grapher kann man nicht nur 2D sondern auch 3D Funktionsgraphen zeichnen lassen. Diese Abbildung zeigt einen 2D Funktiongraphen. Hier die Normalparabel um -3 auf der y-Achse nach unten verschoben.

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Die erste Einsendeaufgabe

Hui, das ist aber ein merkwürdiges Gefühl. Die ersten Studienhefte sind gelesen, gelernt und hoffentlich verstanden. Heute war es dann soweit und ich habe die erste Einsendeaufgabe im Fach Mathematik bearbeitet. Via LaTeX in ein schönes PDF gezimmert und abgeschickt. Themengebiet waren die Mengenlehre, die Zahlenmengen und die vollständige Induktion.

Drückt mir die Daumen ;-)

Eingesendet wird die Aufgabe übrigens über das Onlineportal StudyOnline der Hochschule. Das System ist zwar nicht optimal und könnte ein Designbad gebrauchen, bei dem auch das Bedienkonzept ein paar gute Ideen abbekommt, aber es hat klar definierte Aufgaben und diese erfüllt es.

Trac and the DiscussionPlugin

Today, I tried to integrate the DiscussionPlugin into my Trac 0.10.3 sandbox. But I must notice, that the DiscussionPlugin seems to be incompatible with the version and/or the WebadminPlugin. The discussion plugin where not found several times and disturbed the webadmin. So my last chance was to uninstall the plugin from the plugins folder. Tomorrow, I will try to install it on the python path to make it globally available. Maybe it works better this way.

How to integrate pam with winbind

To use samba with winbind for your pam authentication, you have to edit the process file (e.g. apache2) under /etc/pam.d/ and add the following lines:

  1. #%PAM-1.0
  2. auth    required
  3. account required

If you are already using a configuration, you can add the winbind authentication by simply changing “required” to “sufficient”. The order of the plugins in the file matters to the order of authentication.

The following configuration tries to authenticate against winbind and if this fails, against the unix module.

  1. auth    sufficient
  2. auth    required

How to get mod_auth_pam running on Apache 2.2.x.

mod_auth_pam is not supported and/or developed any longer and the latest available version works only with apache 2.0.x. The new apache 2.2 uses a new authentication mechanism and the old mod_auth_pam does not work, if you only install it to your local apache and use it with the follow configuration:

  1.  AuthPAM_Enabled On
  2.   AuthPAM_FallThrough Off
  3.   AuthType Basic
  4.   AuthName "Testingarea"

You have to turn off the new apache 2.2 basic authentication to get the module up and running. You can do this in two different ways. The first one is to disable the whole module, the second and better one is to disable it through a directive.

For the first solution, you can use the tool a2dismod to disable the module mod_auth_basic.

For the second way, you have to add this lines to the configuration above.

  1. AuthPAM_Enabled On
  2. AuthPAM_FallThrough Off
  3. AuthBasicAuthoritative Off

In the second way, the error.log of apache shows the following lines:

  1. [Wed Feb 21 20:01:35 2007] [error] Internal error: pcfg_openfile() called with NULL filename
  2. [Wed Feb 21 20:01:35 2007] [error] [client] (9)Bad file descriptor: Could not open password file: (null)

The positive message is: you can ignore them ;-) It means, that the mod_auth_pam does not register an AuthBasicProvider and therefore it is null and crashes. Not nice, but it works.

Debian stable vs. testing

Yesterday, I installed Debians current stable version 3.1 rev 4 ‘sarge’ on a vmware. After the installation, I tried to install python2.4, apache2.2, subversion1.4.2 …

I could install the python2.4 package, but the package python was only available for python2.3. After creating the links (e.g. python -> python2.4) manually, I tried to get the apache2.2 package. To use debians apt for this job, I had to add the testing sources to the apt list. After this step, he tried to upgrade my system with a new kernel and some new tools. Enough for me! ;) I went to the debian package page and downloaded the testing net boot cd.