Openfire

Openfire is a real time collaboration (RTC) server licensed under the Open Source Apache License. It uses the only widely adopted open protocol for instant messaging, XMPP (also called Jabber). Openfire is incredibly easy to setup and administer, but offers rock-solid security and performance.

Openfire runs under Windows, Linux, & OSX.

Installing on Ubuntu
Openfire is a pretty simple service to install, the below script should install the needed software on Ubuntu. Openfire also requires a mySQL server, but it dose not need to be ran on the same server.

apt-get update && apt-get -y install default-jdk ant git export JAVA_HOME=/usr/lib/jvm/java-7-openjdk-amd64/ mkdir -p /var/src/ && \ cd /var/src/ && \ git clone https://github.com/igniterealtime/Openfire.git && \ cd /var/src/Openfire/build/ && \ ant cd /var/src/Openfire/target/openfire/bin/ && \ ./openfire.sh
 * 1) !/bin/bash