Last Modified 2012-06-21 by Guest

Ical HowTo using Sunbird or Thunderbird/Lightning with working free/busy

Note: This is not an official Horde document. There is no write support in Horde 3.1/Kronolith 2.1

This document is intended to help administrators configure various parts of horde to link a calendar application with Kronolith. Please feel free to fill in any gaps or to clarify any existing information presented here.

Document Standards

In this document, we assume the following:

  • The latest stable version of Horde and Kronolith.
  • A working version of Horde and Kronolith.
  • A working version of Sunbird or Thunderbird/Lightning extension.

On debian

  • Install php pear package as follow:

apt-get install php4-pear

You can also use php5 package.


Then to make sure pear is working:

pear config-show

You now need to install the pear HTTP_WebDAV_Server package

pear install HTTP_WebDAV_Server-beta

  • Adjust your apache config if necessary.

We found that Sunbird was taking roughly 20 seconds to download the ics file over webdav and that even downloading the file in a browser had the same lag. On investigation it turned out Kronolith was taking about 3 seconds to generate the file and Sunbird was waiting 15 seconds for the connection to close after downloading the file. Turning off KeepAlive in apache.conf (or setting it to a very small value) solved this issue. The default is 15 seconds.

Test it

Launch your Sunbird or Lightning application.

  • Go to calendar
  • New ->
  • On the Network -> iCalendar


15/05/08: Starting with Horde Webmail 1.1 RC4, and as pointed out in that thread, this URL has to be changed like below:

It should ask you for user and password.

Then you should see you calendar and be able to edit events in both Sunbird/Lightning and Kronolith.

I can read my calendar perfectly but not publish. My apache returns a 404 or 403.

Then it should work according to this:

Check also, whether the Apache config allows the PUT method. You should have something similar to

        <Directory /home/www/cal>
            Order deny,allow
            deny from all

where /home/www/cal would be the directory under which horde is installed, in your Apache config.


Free/busy Lightning extension is able to correctly read Horde freebusy file.


* 26/03/08: With Lightning v0.7 and Horde Webmail 1.1RC3, reading and publishing works correctly with a remote calendar as described on this page.
* This does work very nicely with sunbird 0.7 and kronolith 2.2, you must select ical (not webdav) but you do get two way editing.
* 2011-11-23: Using SME Server 8b6, with smeserver-kronolith and kronolith-h3 installed (kronolith v2.3), and the pear additions from above, works fine with Thunderbird 8.0 and Lightning 1.0 -- paul dot warren at wollemisystems dot com


I have found the Solution!

this link has helped me http://lists.freebsd.org/pipermail/freebsd-ports-bugs/2011-July/214620.html

you have to install the pear-HTTP_WebDAV_Server

but it installed in the /usr/share/php dir

you must copy following files to your /usr/share/psa-pear folder, then you can write in your calendar form thunderbird or outlook

/HTTP/WebDAV/ to your psa-pear dir (i think you must copy more than this dir) but it works


Thunderbird ask you for a webdav authentification

Have fun

To get better Performance with more Than 20 Calendars, dturn KeepAlive Off on your Apache server

so the loading on Mailclient should be much faster