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6290c169f5
MIB resolution turns out to be rather CPU intensive, and the current SNMP consumers don't want the resolution anyway.
125 lines
4.9 KiB
Python
125 lines
4.9 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2016 Lenovo
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# This provides a simplified wrapper around snmp implementation roughly
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# mapping to the net-snmp commands
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# net-snmp-python was considered as the API is cleaner, but the ability to
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# patch pysnmp to have it be eventlet friendly has caused it's selection
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# This module simplifies the complex hlapi pysnmp interface
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import confluent.exceptions as exc
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import eventlet
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from eventlet.support.greendns import getaddrinfo
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import pysnmp.smi.error as snmperr
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import socket
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snmp = eventlet.import_patched('pysnmp.hlapi')
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def _get_transport(name):
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# Annoyingly, pysnmp does not automatically determine ipv6 v ipv4
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res = getaddrinfo(name, 161, 0, socket.SOCK_DGRAM)
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if res[0][0] == socket.AF_INET6:
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return snmp.Udp6TransportTarget(res[0][4])
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else:
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return snmp.UdpTransportTarget(res[0][4])
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class Session(object):
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def __init__(self, server, secret, username=None, context=None):
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"""Create a new session to interrogate a switch
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If username is not given, it is assumed that
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the secret is community string, and v2c is used. If a username given,
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it'll assume SHA auth and DES privacy with the secret being the same
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for both.
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:param server: The network name/address to target
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:param secret: The community string or password
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:param username: The username for SNMPv3
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:param context: The SNMPv3 context or index for community indexing
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"""
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self.server = server
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self.context = context
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if username is None:
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# SNMP v2c
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self.authdata = snmp.CommunityData(secret, mpModel=1)
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else:
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self.authdata = snmp.UsmUserData(
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username, authKey=secret, privKey=secret,
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authProtocol=snmp.usmHMACSHAAuthProtocol)
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self.eng = snmp.SnmpEngine()
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def walk(self, oid):
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"""Walk over children of a given OID
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This is roughly equivalent to snmpwalk. It will automatically try to
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be a snmpbulkwalk if possible.
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:param oid: The SNMP object identifier
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"""
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# SNMP is a complicated mess of things. Will endeavor to shield caller
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# from as much as possible, assuming reasonable defaults when possible.
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# there may come a time where we add more parameters to override the
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# automatic behavior (e.g. DES is weak, so it's likely to be
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# overriden, but some devices only support DES)
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tp = _get_transport(self.server)
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ctx = snmp.ContextData(self.context)
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resolvemib = False
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if '::' in oid:
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resolvemib = True
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mib, field = oid.split('::')
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obj = snmp.ObjectType(snmp.ObjectIdentity(mib, field))
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else:
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obj = snmp.ObjectType(snmp.ObjectIdentity(oid))
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walking = snmp.bulkCmd(self.eng, self.authdata, tp, ctx, 0, 10, obj,
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lexicographicMode=False, lookupMib=resolvemib)
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try:
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for rsp in walking:
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errstr, errnum, erridx, answers = rsp
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if errstr:
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errstr = str(errstr)
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finerr = errstr + ' while trying to connect to ' \
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'{0}'.format(self.server)
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if errstr in ('Unknown USM user', 'unknownUserName',
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'wrongDigest', 'Wrong SNMP PDU digest'):
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raise exc.TargetEndpointBadCredentials(finerr)
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# need to do bad credential versus timeout
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raise exc.TargetEndpointUnreachable(finerr)
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elif errnum:
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raise exc.ConfluentException(errnum.prettyPrint() +
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' while trying to connect to '
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'{0}'.format(self.server))
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for ans in answers:
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if not obj[0].isPrefixOf(ans[0]):
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# PySNMP returns leftovers in a bulk command
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# filter out such leftovers
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break
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yield ans
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except snmperr.WrongValueError:
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raise exc.TargetEndpointBadCredentials('Invalid SNMPv3 password')
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if __name__ == '__main__':
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import sys
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ts = Session(sys.argv[1], 'public')
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for kp in ts.walk(sys.argv[2]):
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print(str(kp[0]))
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print(str(kp[1]))
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