When scanning a Unix or Linux system much of the information found is blank.


When SNMP is installed on certain distributions the default configuration file limits the data accessible to the system SNMP node ( that contains basic information such as the system description and object identifier. Access to other SNMP information is prohibited.


Configure the SNMP configuration file which is typically /etc/snmp/snmpd.conf with the appropriate security settings. 

For more information please see the snmpd man pages for your specific distribution.