Ubuntu 6.06 LTS (Dapper Drake) has reached it's end of life. Here the announcement:

[qutoe]Ubuntu announced its 6.06 Server release 5 years ago, on June 1,
2006. For the LTS Server releases, Ubuntu committed to ongoing
security and critical fixes for a period of 5 years. The maintenance
period has now ended for Ubuntu 6.06 LTS Server.

Ubuntu 6.06 LTS was a major milestone for the Ubuntu project, being the
first long-term release. Its retirement evokes memories of Ubuntu as a
younger project, and reminds us of all that we've accomplished together in
the five years since we released the "Dapper Drake".

Thanks to everyone who helped make it happen!

= Upgrade instructions for users of Ubuntu 6.06 LTS =

The supported upgrade path from Ubuntu 6.06 LTS Server is via
Ubuntu 8.04 LTS Server. Instructions and caveats for the upgrade may
be found at https://help.ubuntu.com/community/HardyUpgrades.
For further Ubuntu support, including commercial support options, see
http://www.ubuntu.com/support.

Ubuntu 8.04 LTS Server continues to be actively supported with
security updates and select high-impact bug fixes. All announcements
of official security updates for Ubuntu releases are sent to
the ubuntu-security-announce mailing list, information about which
may be found at
https://lists.ubuntu.com/mailman/listinfo/ubuntu-security-announce.

= About Ubuntu =

Since its launch in October 2004 Ubuntu has become one of the most
highly regarded Linux distributions with millions of users in homes,
schools, businesses and governments around the world. Ubuntu is Open
Source software, costs nothing to download, and users are free to
customise or alter their software in order to meet their needs.

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- mdz