Answer:
Place an ACL on the line when configuring the RO community string.
Explanation:
Controlling Access via SNMP
SNMP is a protocol used by network management systems to monitor and control network-attached devices. Ciscoworks, HP Openview, and other management stations all use SNMP.
SNMP access can be granted on a network device in two ways—read-only and read-write. Read-only access allows the management station to poll the device for statistics and other information, but it does not allow anything to be changed. Read-write access allows the management station to make changes to the configuration of the device.
It's obviously a good idea to make sure you trust the devices allowed to make changes to your configuration, but some versions of SNMP use only a simple shared password to permit access. To make this more secure, an ACL can be applied, which limits the source IP addresses that can use SNMP.
