demo.snmplabs.com
on port 161 (ie default) is an SNMP agent that is open to internet.
It is actually an agent simulator that listens on other ports too; more info at http://snmpsim.sourceforge.net/public-snmp-simulator.html.
snmpwalk -v2c -c public demo.snmplabs.com system
gives this output:
SNMPv2-MIB::sysDescr.0 = STRING: SunOS zeus.snmplabs.com 4.1.3_U1 1 sun4m
SNMPv2-MIB::sysObjectID.0 = OID: SNMPv2-SMI::enterprises.20408
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (288233061) 33 days, 8:38:50.61
SNMPv2-MIB::sysContact.0 = STRING: SNMP Laboratories, [email protected]
SNMPv2-MIB::sysName.0 = STRING: zeus.snmplabs.com
SNMPv2-MIB::sysLocation.0 = STRING: Moscow, Russia
SNMPv2-MIB::sysServices.0 = INTEGER: 72
SNMPv2-MIB::sysORLastChange.0 = Timeticks: (288233113) 33 days, 8:38:51.13
SNMPv2-MIB::sysORID.1 = OID: SNMPv2-SMI::enterprises.20408.1.1
SNMPv2-MIB::sysORDescr.1 = STRING: New system description
SNMPv2-MIB::sysORUpTime.1 = Timeticks: (12) 0:00:00.12