Following is a quick howto for installing the NoMachine free version of NXServer:
. Make sure that you have a DNS entry for the hostname of your NX Server machine or an entry in the server’s /etc/hosts file that points to it’s IP. 
. rpm -i nxclient-3.5.0-7.x86_64.rpm
. rpm -i nxnode-3.5.0-7.x86_64.rpm
. rpm -i nxserver-3.5.0-9.x86_64.rpm
. copy stock config file to server.cfg:
        . # cd /usr/NX/etc
        . # cp server.cfg server.cfg_oem
        . # cp server-redhat.cfg.sample server.cfg
. edit config files:
        . /usr/NX/etc/server.cfg: ensure that the following values are set:
                . EnablePasswordDB = “0”
                . EnableStatistics = “0”
                . EnableNodeMonitoring = “0”
                . EnableUserProfile = “0”
        . /usr/NX/etc/node.cfg
                . EnableSensor = “0”
. generate SSH keys:
        . /usr/NX/bin/nxserver –keygen
        . use the key: /usr/NX/share/keys/default.id_dsa.key in the NX Client config when making a connection to your server