nano /etc/snmp/snmpd.conf

#  Listen for connections from the local system only
#agentAddress  udp:127.0.0.1:161
#  Listen for connections on all interfaces (both IPv4 *and* IPv6)
agentAddress udp:161,udp6:[::1]:161

service snmpd restart

snmpwalk xxx.xxx.x.xx -v 2c -c public system