# Transport tweaks

## SNMPv2c

Send SNMP GET request using the following options:

> - with SNMPv2c, community ‘public’

> - over IPv4/UDP with non-default timeout and no retries

> - to an Agent at demo.snmplabs.com:161

> - for two instances of SNMPv2-MIB::sysDescr.0 MIB object,

> - based on Twisted I/O framework

Functionally similar to:

$ snmpget -v2c -c public -r 0 -t 2 demo.snmplabs.com SNMPv2-MIB::sysDescr.0

    from twisted.internet.task import react
    from pysnmp.hlapi.twisted import *

    def success(args, hostname):
        (errorStatus, errorIndex, varBinds) = args

        if errorStatus:
            print('%s: %s at %s' % (hostname,
                                    errorStatus.prettyPrint(),
                                    errorIndex and varBinds[int(errorIndex) - 1][0] or '?'))
        else:
            for varBind in varBinds:
                print(' = '.join([x.prettyPrint() for x in varBind]))

    def failure(errorIndication, hostname):
        print('%s failure: %s' % (hostname, errorIndication))

    # noinspection PyUnusedLocal
    def getSysDescr(reactor, hostname):
        snmpEngine = SnmpEngine()

        d = getCmd(snmpEngine,
                   CommunityData('public'),
                   UdpTransportTarget((hostname, 161), timeout=2.0, retries=0),
                   ContextData(),
                   ObjectType(ObjectIdentity('SNMPv2-MIB', 'sysDescr', 0)))

        d.addCallback(success, hostname).addErrback(failure, hostname)

        return d

    react(getSysDescr, ['demo.snmplabs.com'])

`Download` script.

See also: library reference.