# 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

    - ‘usr-sha-none’, auth: SHA, no privacy

    - ‘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

- using asyncio network transport (available since Python 3.4)

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

Requires Python 3.4 and later!

    from pysnmp.entity import engine, config
    from pysnmp.entity.rfc3413 import cmdrsp, context
    from pysnmp.carrier.asyncio.dgram import udp
    import asyncio

    # Get the event loop for this thread
    loop = asyncio.get_event_loop()

    # 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))
    )

    # 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)

    # Run asyncio main loop
    loop.run_forever()

`Download` script.

See also: library reference.