端口 1161 上的 SNMP 代理：Net-SNMP 查询超时问题

Question

我有一个基于 pysnmp 的自定义 snmp 代理，我在端口 1161 上启动它，而且我还有自定义 MIB 文件。 我想检查它是否适用于 get 命令，但收到错误“超时：无响应”

my_snmp-agent.py

from pysnmp.hlapi import *
from pysnmp.entity import engine, config
from pysnmp.entity.rfc3413 import cmdrsp, context
from pysnmp import debug
from pysnmp.carrier.asyncore.dgram import udp
from pysnmp.smi import instrum, builder
from pysnmp.proto.api import v2c
import psutil
from pysnmp.smi import exval

# Create SNMP engine
snmpEngine = engine.SnmpEngine()

# Custom OIDs from MY-MIB
CPU_OID = '1.3.6.1.4.1.9999.2'  # MY-MIB::cpuUtil
MEMORY_OID = '1.3.6.1.4.1.9999.1'  # MY-MIB::memoryUtil
DISK_OID = '1.3.6.1.4.1.9999.3'  # MY-MIB::diskUtil

def get_cpu_usage():
    """ CPU usage percentage """
    return int(psutil.cpu_percent(interval=1))

def get_memory_usage():
    """ Memory usage percentage """
    memory = psutil.virtual_memory()
    return int(memory.used * 100 / memory.total)

def get_disk_usage():
    """ Disk usage percentage: main partition """
    disk = psutil.disk_usage('/')
    return int(disk.used * 100 / disk.total)

def create_variable_binds(oid, value):
    return [ObjectType(ObjectIdentity(oid), Integer32(value))]

def create_snmp_agent():
    """ an SNMP agent listening for GET requests """
    
    def process_snmp_request(snmpEngine, stateReference, contextEngineId, contextName, varBinds, cbCtx):
        """ Processing SNMP GET requests """
        oid, = [x[0] for x in varBinds]
        oid_str = str(oid)
    
        print("Received request for OID:", oid_str)
    
        # Using appropriate response based on the OID
        if oid_str.startswith(CPU_OID):
            value = get_cpu_usage()
        elif oid_str.startswith(MEMORY_OID):
            value = get_memory_usage()
        elif oid_str.startswith(DISK_OID):
            value = get_disk_usage()
        else:
            value = 0  # Default response for unrecognized OIDs

        # Creating and sending the response
        varBinds = create_variable_binds(oid, value)
        cmdrsp.sendVarBinds(snmpEngine, stateReference, contextEngineId, contextName, varBinds, cbCtx)

    # Registering SNMP application
    cmdrsp.GetCommandResponder(snmpEngine, CommunityData('public', mpModel=1))

    # Processing SNMP GET requests
    snmpContext = context.SnmpContext(snmpEngine)
    snmpContext.registerContextName(v2c.OctetString('public'), process_snmp_request)
    # Transport (UDP over IPv4)
    config.addTransport(snmpEngine, udp.domainName, udp.UdpTransport().openServerMode(('127.0.0.1', 1161)))

    print("SNMP Agent is running...")
    snmpEngine.transportDispatcher.jobStarted(1)

    try:
        # Start dispatcher for receiving queries and sending responses
        snmpEngine.transportDispatcher.runDispatcher()
    except:
        snmpEngine.transportDispatcher.closeDispatcher()
        raise

if __name__ == "__main__":
    create_snmp_agent()

我的MIB.txt

MY-MIB DEFINITIONS ::= BEGIN
  IMPORTS
      MODULE-IDENTITY, OBJECT-TYPE, Integer32 
      FROM SNMPv2-SMI;
  
  myMIB MODULE-IDENTITY
      LAST-UPDATED "202401260000Z"
      ORGANIZATION "MyOrganization"
      CONTACT-INFO "[email protected]"
      DESCRIPTION "MIB for custom SNMP agent"
      REVISION "202401260000Z"
      DESCRIPTION "This custom version MIB"
      ::= { enterprises 9999 }

  enterprises OBJECT IDENTIFIER ::= { iso(1) org(3) dod(6) internet(1) private(4) enterprises(1) }

  memoryUtil OBJECT-TYPE
      SYNTAX Integer32
      MAX-ACCESS read-only
      STATUS current
      DESCRIPTION "Memory Utilization in percentage"
      ::= { myMIB 1 }

  cpuUtil OBJECT-TYPE
      SYNTAX Integer32
      MAX-ACCESS read-only
      STATUS current
      DESCRIPTION "CPU Utilization in percentage"
      ::= { myMIB 2 }

  diskUtil OBJECT-TYPE
      SYNTAX Integer32
      MAX-ACCESS read-only
      STATUS current
      DESCRIPTION "Disk Utilization in percentage"
      ::= { myMIB 3 }
END

编译成功。

smidump -k -f python -o my-mib.py MY-MIB.txt

在第一个航站楼启动我的代理：

python3 my_snmp-agent.py
SNMP Agent is running...

在第二个终端中使用 Net-SNMP 进行测试：

snmpget -v2c -c public 127.0.0.1:1161 1.3.6.1.4.1.9999.1
Timeout: No Response from 127.0.0.1:1161.
snmpwalk -v2c -c public 127.0.0.1:1161 1.3.6.1.4.1.9999
Timeout: No Response from 127.0.0.1:1161
snmpbulkget -v2c -c public 127.0.0.1:1161 1.3.6.1.4.1.9999.1 1.3.6.1.4.1.9999.2 1.3.6.1.4.1.9999.3
Timeout: No Response from 127.0.0.1:1161

在第二个终端中使用调试（-d）选项：

snmpget -v2c -c public -d 127.0.0.1:1161 1.3.6.1.4.1.9999.1
No log handling enabled - using stderr logging

Sending 43 bytes to UDP: [127.0.0.1]:1161->[0.0.0.0]:0
0000: 30 29 02 01  01 04 06 70  75 62 6C 69  63 A0 1C 02    0).....public?..
0016: 04 19 1E B4  74 02 01 00  02 01 00 30  0E 30 0C 06    ...?t......0.0..
0032: 08 2B 06 01  04 01 CE 0F  01 05 00                    .+....?....

在第三个终端中启动 tcpdump：

tcpdump -i any port 1161 -vv
tcpdump: data link type PKTAP
tcpdump: listening on any, link-type PKTAP (Apple DLT_PKTAP), capture size 262144 bytes
19:20:30.761706 IP (tos 0x0, ttl 64, id 13838, offset 0, flags [none], proto UDP (17), length 71, bad cksum 0 (->4696)!)
    localhost.49661 > localhost.health-polling: [bad udp cksum 0xfe46 -> 0x1ad6!] UDP, length 43
19:20:30.761729 IP (tos 0x0, ttl 64, id 13838, offset 0, flags [none], proto UDP (17), length 71, bad cksum 0 (->4696)!)
    localhost.49661 > localhost.health-polling: [bad udp cksum 0xfe46 -> 0x1ad6!] UDP, length 43
19:20:31.766991 IP (tos 0x0, ttl 64, id 17114, offset 0, flags [none], proto UDP (17), length 71, bad cksum 0 (->39ca)!)

Answer 1

答案是您的代码中未配置 OID 访问。

您需要致电

config.addVacmUser

以开放对任何社区/用户名的 OID 访问权限。

完整的示例是这里。