All those information can be polled through SNMP. Orion can poll the relevant OID either by default or by configuring it with the Universal Device Poller utility.
You will have to ensure that a SNMP agent is installed on your linux servers in order to reply to the SNMP requests coming from the Orion NPM server.
The most well known SNMP agent for linux boxes is Net-SNMP.
Many thanks Yann.
i'll test that and see how ti does.