From Fedora Project Wiki

Using Fedora Core's up2date with Fedora Legacy

The Fedora Core up2date program is, by default, only configured to update from the Red Hat servers. Once your Fedora Core version reaches End of Life, you will want to reconfigure it to use the Fedora Legacy repository so that you can continue to receive updates.

Step 1: Preliminaries: Install up2date

This document assumes you have already installed and are using up2date on your system. If not, it is perhaps better to use yum instead; please see here for information on how to install and use yum on your machine.

Step 2: Reconfigure up2date

The configuration file for up2date is /etc/sysconfig/rhn/sources. It is a plain text file and can be edited by an editor of your choice (e.g. vim, pico, emacs, joe, gedit, kedit). Lines without a leading "#" character are "active" lines. Lines with a leading "#" are comments lines, and are not used for updates. The following lines should already be in your existing file:

yum fedora-core-1
yum updates-released

Put a "#" character in front of each of the lines above if they don't already have one. This marks them as comments, and stops updates from being done from the standard Red Hat Fedora Core 1 repositories.

Now you want to add to that file the Fedora Legacy repository for Fedora Core. Let's assume you are using Fedora Core 1 for this example. Enter the following into your /etc/sysconfig/rhn/sources file:

yum os
yum updates
yum legacy-utils

Save the edited file and run up2date (either on the command line or using its GUI interface). It should now show that it is fetching the package list from the Fedora Legacy repositories.

From this point on, you simply use up2date as you always have.