Overview
This document details how to install MySQL on Linux, and how to configure it to work with Caucus.  The precise details will vary slightly for different flavors of unix.

I. Download and install MySQL
Most linux/unix systems today include MySQL, but if your server does not already have version 4.1 or later, you may need to install or upgrade it.

There are many ways to install MySQL, including running update software (such as 'yum' or 'up2date'), building from source, installing a binary package, or installing a set of RPM files.  These instructions detail using the RPM files, which we believe is the simplest method.  Adapt these instructions accordingly if you are using a different download method.

1. From www.mysql.com/downloads/mysql-4.1.html, download the Linux RPM files listed below.  (The precise version numbers may vary; this is just an example.)

   Category	sample file
   Server 4.1	MySQL-server-4.1.11-0.i386.rpm
   Libraries and header files 4.1	MySQL-devel-4.1.11-0.i386.rpm
   Dynamic client libraries 4.1	MySQL-shared-4.1.11-0.i386.rpm
   Client programs 4.1	MySQL-client-4.1.11-0.i386.rpm

2. As root, install the rpm's:

      rpm -i MySQL-server-4.1.11-0.i386.rpm
      rpm -i MySQL-client-4.1.11-0.i386.rpm
      rpm -i MySQL-devel-4.1.11-0.i386.rpm
      rpm -i MySQL-shared-4.1.11-0.i386.rpm
   

   (If you already have an earlier version of MySQL installed, you should use "rpm -U" instead of "rpm -i", and you may need to add "--nodeps" to several of the rpm commands.  But don't worry about it unless "rpm -i" complains!)

II. Secure MySQL
There is a great deal of literature about how to properly secure MySQL depending on your intended use and circumstances.  The MySQL Reference Manual is an excellent place to start. 

In these instructions, we assume that MySQL should only be accessible from the local host (not by other clients over the network), and the absolute minimum of 'root' level access.

1. Always start mysql for local access only.  As root, edit /etc/init.d/mysql, and find the line that actually runs mysqld_safe.  Add the "--skip-network" option.  The result should look something like:

      $bindir/mysqld_safe --datadir=$datadir --pid-file=$pid_file --skip-networking &
   

   Stop and restart mysql:

      /etc/init.d/mysql stop
      /etc/init.d/mysql start
   

2. Limit root and non-essential access.  Change the default (empty) root password.  Delete any non-localhost 'root' users, and any 'blank' users.

      mysqladmin -u root password new_password
   
      mysql -u root --password=new_password
      mysql> use mysql;
      mysql> delete from user where host = '%';
      mysql> delete from user where user = '';
      mysql> delete from db where user = '';
      mysql> select user, host from user;
   

   If you see any 'root' users other than root@localhost, delete them -- e.g.

      mysql> delete from user where user = 'root' and host='myhost.com'
   

   Flush the privileges.

      mysql> flush privileges;
      mysql> quit
   

III. Set MySQL parameters
If you expect to have long-running Caucus sessions (i.e. someone logged in for more than an hour at a time), you will need to raise the MySQL session limits. 

Edit /etc/my.cnf, and in the [mysqld] section, add:

   interactive_timeout = 28800
   wait_timeout        = 28800
   connect_timeout     = 28800

Then restart the MySQL service.

The rest of the Caucus-related configuation is done automatically by the Caucus 'install' script.  You will need the MySQL 'root' password.