To build net-snmp, please enter apps config,

Network Applications  ---> 
[*] net-snmp                   
[*]   Build mini agent         
[ ]   Build Applications (NEW) 
[*]   Build static             
[ ]   Install manuals (NEW)    
[ ]   Install scripts (NEW)    
[*]   Install MIBs             
[ ]     Enable MIB loading (NEW)
[ ]   Disable SNMP v1 (NEW)    
[ ]   Disable SNMP v2c (NEW)   
[ ]   IPv6 support (NEW)       
[ ]   Exclude transports (NEW) 
[ ]   With OpenSSL (NEW)       
[ ]   Override defaults (NEW)  
[ ]   Additional MIBS (NEW)    

Create a snmpd.conf to romfs/etc/snmp/snmpd.conf, with single line,
rwcommunity  public


Boot your nios2 board, config ethernet. Then start snmpd,

> snmpd &
 
Query the nios2 board from another Linux box with net-snmp installed:

$ snmpwalk -v 1 -c public 172.20.11.51 system
SNMPv2-MIB::sysDescr.0 = STRING: uClinux uClinux 2.6.23-uc0-gb13c4d1f-dirty #138 PREEMPT Wed Mar 5 12:48:49 MST 2008 nios2nommu
SNMPv2-MIB::sysObjectID.0 = OID: NET-SNMP-MIB::netSnmpAgentOIDs.10
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (80124) 0:13:21.24
SNMPv2-MIB::sysContact.0 = STRING: jchen@
SNMPv2-MIB::sysName.0 = STRING: uClinux
SNMPv2-MIB::sysLocation.0 = STRING: Unknown
SNMPv2-MIB::sysORLastChange.0 = Timeticks: (16) 0:00:00.16
SNMPv2-MIB::sysORID.1 = OID: IF-MIB::ifMIB
SNMPv2-MIB::sysORID.2 = OID: SNMPv2-MIB::snmpMIB
SNMPv2-MIB::sysORID.3 = OID: TCP-MIB::tcpMIB
SNMPv2-MIB::sysORID.4 = OID: IP-MIB::ip
SNMPv2-MIB::sysORID.5 = OID: UDP-MIB::udpMIB
SNMPv2-MIB::sysORID.6 = OID: SNMP-VIEW-BASED-ACM-MIB::vacmBasicGroup
SNMPv2-MIB::sysORID.7 = OID: SNMP-FRAMEWORK-MIB::snmpFrameworkMIBCompliance
SNMPv2-MIB::sysORID.8 = OID: SNMP-MPD-MIB::snmpMPDCompliance
SNMPv2-MIB::sysORID.9 = OID: SNMP-USER-BASED-SM-MIB::usmMIBCompliance
SNMPv2-MIB::sysORDescr.1 = STRING: The MIB module to describe generic objects for network interface sub-layers
SNMPv2-MIB::sysORDescr.2 = STRING: The MIB module for SNMPv2 entities
SNMPv2-MIB::sysORDescr.3 = STRING: The MIB module for managing TCP implementations
SNMPv2-MIB::sysORDescr.4 = STRING: The MIB module for managing IP and ICMP implementations
SNMPv2-MIB::sysORDescr.5 = STRING: The MIB module for managing UDP implementations
SNMPv2-MIB::sysORDescr.6 = STRING: View-based Access Control Model for SNMP.
SNMPv2-MIB::sysORDescr.7 = STRING: The SNMP Management Architecture MIB.
SNMPv2-MIB::sysORDescr.8 = STRING: The MIB for Message Processing and Dispatching.
SNMPv2-MIB::sysORDescr.9 = STRING: The management information definitions for the SNMP User-based Security Model.
SNMPv2-MIB::sysORUpTime.1 = Timeticks: (3) 0:00:00.03
SNMPv2-MIB::sysORUpTime.2 = Timeticks: (6) 0:00:00.06
SNMPv2-MIB::sysORUpTime.3 = Timeticks: (6) 0:00:00.06
SNMPv2-MIB::sysORUpTime.4 = Timeticks: (6) 0:00:00.06
SNMPv2-MIB::sysORUpTime.5 = Timeticks: (6) 0:00:00.06
SNMPv2-MIB::sysORUpTime.6 = Timeticks: (7) 0:00:00.07
SNMPv2-MIB::sysORUpTime.7 = Timeticks: (16) 0:00:00.16
SNMPv2-MIB::sysORUpTime.8 = Timeticks: (16) 0:00:00.16
SNMPv2-MIB::sysORUpTime.9 = Timeticks: (16) 0:00:00.16