Various SNMP versions

Multiple SNMP USM users

Listen and respond to SNMP GET/SET/GETNEXT/GETBULK queries with the following options:

  • SNMPv3
  • with USM user ‘usr-md5-des’, auth: MD5, priv DES or with USM user ‘usr-sha-none’, auth: SHA, no privacy with USM user ‘usr-sha-aes128’, auth: SHA, priv AES
  • allow access to SNMPv2-MIB objects (1.3.6.1.2.1)
  • over IPv4/UDP, listening at 127.0.0.1:161

Either of the following Net-SNMP commands will walk this Agent:

$ snmpwalk -v3 -u usr-md5-des -l authPriv -A authkey1 -X privkey1 localhost .1.3.6
$ snmpwalk -v3 -u usr-sha-none -l authNoPriv -a SHA -A authkey1 localhost .1.3.6
$ snmpwalk -v3 -u usr-sha-aes128 -l authPriv -a SHA -A authkey1 -x AES -X privkey1 localhost .1.3.6
from pysnmp.entity import engine, config
from pysnmp.entity.rfc3413 import cmdrsp, context
from pysnmp.carrier.asyncore.dgram import udp

# Create SNMP engine
snmpEngine = engine.SnmpEngine()

# Transport setup

# UDP over IPv4
config.addTransport(
    snmpEngine,
    udp.domainName,
    udp.UdpTransport().openServerMode(('127.0.0.1', 161))
)

# SNMPv3/USM setup

# user: usr-md5-des, auth: MD5, priv DES
config.addV3User(
    snmpEngine, 'usr-md5-des',
    config.usmHMACMD5AuthProtocol, 'authkey1',
    config.usmDESPrivProtocol, 'privkey1'
)
# user: usr-sha-none, auth: SHA, priv NONE
config.addV3User(
    snmpEngine, 'usr-sha-none',
    config.usmHMACSHAAuthProtocol, 'authkey1'
)
# user: usr-sha-none, auth: SHA, priv AES
config.addV3User(
    snmpEngine, 'usr-sha-aes128',
    config.usmHMACSHAAuthProtocol, 'authkey1',
    config.usmAesCfb128Protocol, 'privkey1'
)

# Allow full MIB access for each user at VACM
config.addVacmUser(snmpEngine, 3, 'usr-md5-des', 'authPriv', (1, 3, 6, 1, 2, 1), (1, 3, 6, 1, 2, 1))
config.addVacmUser(snmpEngine, 3, 'usr-sha-none', 'authNoPriv', (1, 3, 6, 1, 2, 1), (1, 3, 6, 1, 2, 1))
config.addVacmUser(snmpEngine, 3, 'usr-sha-aes128', 'authPriv', (1, 3, 6, 1, 2, 1), (1, 3, 6, 1, 2, 1))

# Get default SNMP context this SNMP engine serves
snmpContext = context.SnmpContext(snmpEngine)

# Register SNMP Applications at the SNMP engine for particular SNMP context
cmdrsp.GetCommandResponder(snmpEngine, snmpContext)
cmdrsp.SetCommandResponder(snmpEngine, snmpContext)
cmdrsp.NextCommandResponder(snmpEngine, snmpContext)
cmdrsp.BulkCommandResponder(snmpEngine, snmpContext)

# Register an imaginary never-ending job to keep I/O dispatcher running forever
snmpEngine.transportDispatcher.jobStarted(1)

# Run I/O dispatcher which would receive queries and send responses
try:
    snmpEngine.transportDispatcher.runDispatcher()
except:
    snmpEngine.transportDispatcher.closeDispatcher()
    raise

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Multiple SNMP communities

Respond to SNMP GET/SET/GETNEXT queries with the following options:

  • SNMPv1
  • with SNMP community “public” (read access) or “private” (write access)
  • allow access to SNMPv2-MIB objects (1.3.6.1.2.1)
  • over IPv4/UDP, listening at 127.0.0.1:161

Allow read/write access to all objects in the same MIB subtree.

The following Net-SNMP’s commands will GET/SET a value at this Agent:

$ snmpget -v1 -c public 127.0.0.1 SNMPv2-MIB::sysLocation.0
$ snmpset -v1 -c private 127.0.0.1 SNMPv2-MIB::sysLocation.0 s “far away”
from pysnmp.entity import engine, config
from pysnmp.entity.rfc3413 import cmdrsp, context
from pysnmp.carrier.asyncore.dgram import udp

# Create SNMP engine with autogenernated engineID and pre-bound
# to socket transport dispatcher
snmpEngine = engine.SnmpEngine()

# Transport setup

# UDP over IPv4
config.addTransport(
    snmpEngine,
    udp.domainName,
    udp.UdpTransport().openServerMode(('127.0.0.1', 161))
)

# SNMPv1 setup

# SecurityName <-> CommunityName mapping.
# Here we configure two distinct CommunityName's to control read and write
# operations.
config.addV1System(snmpEngine, 'my-read-area', 'public')
config.addV1System(snmpEngine, 'my-write-area', 'private')

# Allow full MIB access for this user / securityModels at VACM
config.addVacmUser(snmpEngine, 1, 'my-read-area', 'noAuthNoPriv', (1, 3, 6, 1, 2, 1))
config.addVacmUser(snmpEngine, 1, 'my-write-area', 'noAuthNoPriv', (1, 3, 6, 1, 2, 1), (1, 3, 6, 1, 2, 1))

# Get default SNMP context this SNMP engine serves
snmpContext = context.SnmpContext(snmpEngine)

# Register SNMP Applications at the SNMP engine for particular SNMP context
cmdrsp.GetCommandResponder(snmpEngine, snmpContext)
cmdrsp.SetCommandResponder(snmpEngine, snmpContext)
cmdrsp.NextCommandResponder(snmpEngine, snmpContext)

# Register an imaginary never-ending job to keep I/O dispatcher running forever
snmpEngine.transportDispatcher.jobStarted(1)

# Run I/O dispatcher which would receive queries and send responses
try:
    snmpEngine.transportDispatcher.runDispatcher()
except:
    snmpEngine.transportDispatcher.closeDispatcher()
    raise

Download script.

See also: library reference.