24.6.3. Configuring Net-SNMP

To change the Net-SNMP Agent Daemon configuration, edit the /etc/snmp/snmpd.conf configuration file. The default snmpd.conf file shipped with Red Hat Enterprise Linux 6 is heavily commented and serves as a good starting point for agent configuration.
This section focuses on two common tasks: setting system information and configuring authentication. For more information about available configuration directives, see the snmpd.conf(5) manual page. Additionally, there is a utility in the net-snmp package named snmpconf which can be used to interactively generate a valid agent configuration.
Note that the net-snmp-utils package must be installed in order to use the snmpwalk utility described in this section.

Note

For any changes to the configuration file to take effect, force the snmpd service to re-read the configuration by running the following command as root:
service snmpd reload

24.6.3.1. Setting System Information

Net-SNMP provides some rudimentary system information via the system tree. For example, the following snmpwalk command shows the system tree with a default agent configuration.
~]# snmpwalk -v2c -c public localhost system
SNMPv2-MIB::sysDescr.0 = STRING: Linux localhost.localdomain 2.6.32-122.el6.x86_64 #1 SMP Wed Mar 9 23:54:34 EST 2011 x86_64
SNMPv2-MIB::sysObjectID.0 = OID: NET-SNMP-MIB::netSnmpAgentOIDs.10
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (99554) 0:16:35.54
SNMPv2-MIB::sysContact.0 = STRING: Root <root@localhost> (configure /etc/snmp/snmp.local.conf)
SNMPv2-MIB::sysName.0 = STRING: localhost.localdomain
SNMPv2-MIB::sysLocation.0 = STRING: Unknown (edit /etc/snmp/snmpd.conf)
By default, the sysName object is set to the host name. The sysLocation and sysContact objects can be configured in the /etc/snmp/snmpd.conf file by changing the value of the syslocation and syscontact directives, for example:
syslocation Datacenter, Row 3, Rack 2
syscontact UNIX Admin <admin@example.com>
After making changes to the configuration file, reload the configuration and test it by running the snmpwalk command again:
~]# service snmpd reload
Reloading snmpd: [  OK  ]
~]# snmpwalk -v2c -c public localhost system
SNMPv2-MIB::sysDescr.0 = STRING: Linux localhost.localdomain 2.6.32-122.el6.x86_64 #1 SMP Wed Mar 9 23:54:34 EST 2011 x86_64
SNMPv2-MIB::sysObjectID.0 = OID: NET-SNMP-MIB::netSnmpAgentOIDs.10
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (158357) 0:26:23.57
SNMPv2-MIB::sysContact.0 = STRING: UNIX Admin <admin@example.com>
SNMPv2-MIB::sysName.0 = STRING: localhost.localdomain
SNMPv2-MIB::sysLocation.0 = STRING: Datacenter, Row 3, Rack 2