Install JRE

sudo apt-get install openjdk-7-jre

Get the url for the newest version of Openfire from

http://www.igniterealtime.org/downloads/

and download Openfire with wget

wget http://www.igniterealtime.org/downloads/download-landing.jsp?file=openfire/openfire_4_0_1.tar.gz

or download it and move it to the server via scp.

Extract

tar -xvzf openfire_4_0_1.tar.gz

and move to /usr/local/openfire

mv openfire /usr/local/

Open the configfile

vi /usr/local/openfire/conf/openfire.xml

remove the comment for network and insert yours

<network>
<interface>123.45.67.89</interface>
</network>

Start Openfire

/usr/local/openfire/bin/openfire start

If you havent install MySQL yet, check that site MySQL
Otherwise execute the following two commands

mysqladmin -u root -p create openfire
cat /usr/local/openfire/resources/database/openfire_mysql.sql | mysql -u root -p openfire;

Open the interface in your browser

http://123.45.67.89:9090

Click through the setup, at Database Settings select Standard Database Connection
Next screen, select MySQL in the dropdown and insert your hostname (localhost) and database (openfire)

jdbc:mysql://localhost:3306/openfire?rewriteBatchedStatements=true

insert your info and leave settings default.