If your linux distribution is based on RPM, simply fetch the file
OsirisTools-X-Y.rpm and run this command as root:
rpm -Uvh OsirisTools-X-Y.rpm
Remember to replace X and Y with the correct values !

If yout system is not rpm-based, fetch nrtd, oclient, oclient.static, and
nettrigger, and make them executable:
chmod a+x nrtd oclient oclient.static nettrigger