#
# Command Generator
#
# Send SNMP GET request using the following options:
#
# * with SNMPv2c, community 'public'
# * over IPv4/UDP
# * to an Agent at demo.snmplabs.com:161
# * for an OID in string form 
# * use custom timeout and request retries values
#
# Transport timing settings (maximum number of request retries and 
# individual request timeout in seconds) can be set on a per-target basis
# as explained by the code that follows.
#
# Keep in mind that while timeout value can be specified in fractions of a
# second, default pysnmp timer resolution is quite low (about 0.5 sec)
# so there's no much point in using timeouts which is not a multiple of 0.5
# Internal timer can be programmatically adjusted to finer resolution if needed.
#
# If retries value is set to 0, pysnmp will issue a single request. Even
# if no response arrives, there will be no retry. Likewise, retries=1
# means one initial request plus one retry.
#
from pysnmp.entity.rfc3413.oneliner.cmdgen import *

for errorIndication, \
    errorStatus, errorIndex, \
    varBinds in getCmd(SnmpEngine(),
                       CommunityData('public'),
                       UdpTransportTarget(
                           ('demo.snmplabs.com', 161), timeout=1.5, retries=0
                       ),
                       ContextData(),
                       ObjectType(ObjectIdentity('1.3.6.1.2.1.1.1.0'))):
    # Check for errors and print out results
    if errorIndication:
        print(errorIndication)
    else:
        if errorStatus:
            print('%s at %s' % (
                    errorStatus.prettyPrint(),
                    errorIndex and varBinds[int(errorIndex)-1][0] or '?'
                )
            )
        else:
            for varBind in varBinds:
                print(' = '.join([ x.prettyPrint() for x in varBind ]))
    break