Get Red Hat Linux 9.0 Installation CD's. (This is a set of 3.)
Think about the non-standard daemons you have running (e.g., an HTTP or FTP server), if any, or any non-standard configuration that you want to preserve. The upgrade might break these things, so be sure you know how to repair them after the upgrade.
Unless you are feeling lucky, you might want to backup any important files that you have on the computer.
Shutdown the computer.
Set computer's BIOS to boot off of the CD-ROM drive. (If it is not already set to do so.)
Boot computer off of CD #1.
Anaconda (the Red Hat installer) will run. Answer its questions.
Anaconda will ask you what language you would like to use. Select English.
Anaconda will ask you what type of keyboard you have. Tell it that you have a U.S. English keyboard.
Anaconda will ask you what type of mouse you have. If you don't know the answer to this, then it is probably okay to confirm the pre-selected default that Anaconda presents to you (which will likely be either a Generic Three Button P/2 Mouse or a Generic Three Button USB Mouse) but it is better if you specify the more precise mouse type that you actually have. This will typically be either a Logitech PS/2 MouseMan+/FirstMouse+, or a Logitech USB Wheel Mouse, though it is conceivable that you have Microsoft Intellimouse of either the PS/2 or USB variety.
Anaconda will ask you whether you want to perform an upgrade or a new Red Hat Linux Installation. Select Upgrade. There will be a drop-down box indicating where Anaconda has found Red Hat installations. If it finds more than one, or the one it finds isn't on /dev/hda, then you are on your own. Do not check "Customize packages to be upgraded" unless you are in the mood to be a control freak.
If Anaconda asks you if you would like to migrate any filesystems to "ext3", say that you would.
Anaconda will ask you if you would like to update the boot loader configuration. Say that you would, and accept any defaults for other questions that it might ask you about this.
When Anaconda asks you to confirm that you want to do the upgrade, say that you would. Now you will need to wait for Anaconda to do its job. Twice, it will ask you to replace the CD with the next one.
When Anaconda asks you to confirm that it will reboot the system, first remove the CD from the CD-ROM drive and then okay the reboot. While the system is rebooting, you may (or may not) want to go into the BIOS and turn off booting from the CD-ROM.
Log in to the computer as root and do the following:
% chkconfig --levels 0123456 isdn off
% chkconfig --levels 0123456 iptables off
% service iptables stop
Make sure that the sendmail-cf rpm is installed by doing
% rpm -q sendmail-cf
If the above command indicates that sendmail-cf is not already installed then install sendmail-cf as follows:
% cd /usr/bin
% ./redhat-config-packages
Replace /etc/mail/sendmail.mc with this file and then do the following:
% cd /etc/mail
% make
Repair any nonstandard configuration (e.g., HTTP or FTP servers) that might have been broken by the upgrade.
Reboot the computer.
Log in and send yourself some email to make sure that email is working correctly. Mail sent from user1 on the local machine to user2 on the local machine should get redirected to user2@space.mit.edu and should appear to come from user1@space.mit.edu.
Check to make sure that your non-standard daemons and other non-standard configuration, if you have any, is behaving as you would like.