PySNMP 是一个纯粹用Python实现的SNMP,用PySNMP的最抽象的API为One-line Applications,其中有两类API：同步的和非同步的,都在模块pysnmp.entity.rfc3413.oneliner.cmdgen 中实现,如下是Get方式与Walk方式的基本实现.

首先需要在系统中安装SNMP客户端,对于Linux平台来说只需要执行如下配置过程即可.

[root@localhost ~]# yum install -y net-snmp
[root@localhost ~]# cat /etc/snmp/snmpd.conf |grep -vE "^#|^$"
com2sec notConfigUser  default       public

group   notConfigGroup v1           notConfigUser
group   notConfigGroup v2c           notConfigUser

view    systemview    included   .1
view    systemview    included   .1

access  notConfigGroup  ""  any  noauth  exact  systemview none none

[root@localhost ~]# systemctl restart snmpd
[root@localhost ~]# systemctl enable snmpd

如果是Windows系统则需要在客户机服务列表，开启SNMP支持，并设置好一个团体名称，如下图。

当我们配置好客户端后，服务端就客户获取数据了，我们以一个OID序号为例，我们查询特定序号对应的名称，然后将其记录下来，例如下面这样。

C:\Users\admin> snmpwalk -v 2c -c public 192.168.1.101 .1.3.6.1.2.1.25.2.2
HOST-RESOURCES-MIB::hrMemorySize.0 = INTEGER: 2096632 KBytes

首先我们不使用PySNMP模块直接开线程调用看看,该代码如下所示.

import os,re,time

# 通过SNMP收集主机CPU利用率: 通过SNMP协议,收集目标主机的CPU利用率(百分比),并返回JSON字符串.
def Get_CPU_Info(addr):
    try:
        Head = ["HostName","CoreLoad","CpuUser","CpuSystem","CpuIdle"]
        CPU = []
        ret = os.popen("snmpwalk -v 2c -c nmap " + addr + " .1.3.6.1.2.1.1.5")
        CPU.append(ret.read().split(":")[3].strip())
        ret = os.popen("snmpwalk -v 2c -c nmap " + addr + " .1.3.6.1.2.1.25.3.3.1.2")
        CPU.append(ret.read().split(":")[3].strip())

        for i in [9,10,11]:
            ret = os.popen("snmpwalk -v 2c -c nmap " + addr + " 1.3.6.1.4.1.2021.11.{}.0".format(i))
            ret = ret.read()
            Info = ret.split(":")[3].strip()
            CPU.append(Info)
        return dict(zip(Head,CPU))
    except Exception:
        return 0

# 通过SNMP获取系统CPU负载信息: 分别获取到系统的1,5,15分钟的负载信息,并返回JSON格式.
def Get_Load_Info(addr):
    try:
        Head = ["HostName","Load1","Load5","Load15"]
        SysLoad = []
        ret = os.popen("snmpwalk -v 2c -c nmap " + addr + " .1.3.6.1.2.1.1.5")
        SysLoad.append(ret.read().split(":")[3].strip())

        ret = os.popen("snmpwalk -v 2c -c nmap " + addr + " .1.3.6.1.4.1.2021.10.1.3")
        load = list(re.sub(".*STRING: ", "", ret.read()).split("\n"))
        SysLoad.append(load[0])
        SysLoad.append(load[1])
        SysLoad.append(load[2])
        return dict(zip(Head,SysLoad))
    except Exception:
        return 0

# 通过SNMP获取系统内存占用: 内存利用率，获取到之后，将其转化为字典格式保存。
def Get_Mem_Info(addr):
    try:
        Head = ["HostName","memTotalSwap","memAvailSwap","memTotalReal","memTotalFree"]
        SysMem = []
        ret = os.popen("snmpwalk -v 2c -c nmap " + addr + " .1.3.6.1.2.1.1.5")
        SysMem.append(ret.read().split(":")[3].strip())
        ret = os.popen("snmpwalk -v 2c -c nmap " + addr + " .1.3.6.1.4.1.2021.4")
        mem = ret.read().split("\n")
        for i in [2,3,4,6]:
            SysMem.append(re.sub(".*INTEGER: ","",mem[i]).split(" ")[0])
        return dict(zip(Head,SysMem))
    except Exception:
        return 0

# 通过SNMP获取系统磁盘数据: 这个案例并不完整,我只写了一点,后面有个问题一直没有解决.
def Get_Disk_Info(addr):
    try:
        dic = {}
        list = []
        ret = os.popen("snmpwalk -v 2c -c nmap " + addr + " HOST-RESOURCES-MIB::hrStorageDescr")
        DiskName = ret.read().split("\n")
        ret =os.popen("snmpwalk -v 2c -c nmap " + addr + " HOST-RESOURCES-MIB::hrStorageUsed")
        DiskUsed = ret.read().split("\n")
        ret = os.popen("snmpwalk -v 2c -c nmap " + addr + " HOST-RESOURCES-MIB::hrStorageSize")
        DiskSize = ret.read().split("\n")

        for i in range(1,len(DiskName) - 7):
            dic["Name"]= DiskName[i + 5].split(":")[3]
            dic["Used"]= DiskUsed[i + 5].split(":")[3]
            dic["Size"]= DiskSize[i + 5].split(":")[3]
            list.append(dic)
        return list
    except Exception:
        return 0

if __name__ == '__main__':
    for i in range(100):
        dic = Get_CPU_Info("192.168.1.20")
        print(dic)
        time.sleep(1)

我们使用pysnmp模块来做，安装pysnmp很简单，执行命令pip install pysnmp 即可，安装后使用以下代码执行即可获取到目标数据，获取方式分为两种一种为Get另一种为Walk.

from pysnmp.hlapi import *
import os,sys

class NetSNMP():
    def __init__(self,address,region):
        self.region = region
        self.address = address

    # 获取指定数据的方法
    def GetNumber(self,oid,sub_oid,sub_id):
        iterator = getCmd(SnmpEngine(),
                          CommunityData(self.region),
                          UdpTransportTarget((self.address, 161)),
                          ContextData(),
                          ObjectType(ObjectIdentity(oid, sub_oid, sub_id)))
        errorIndication, errorStatus, errorIndex, varBinds = next(iterator)

        if errorIndication:
            return False
        else:
            if errorStatus:
                return False
            else:
                for varBind in varBinds:
                    return [x.prettyPrint() for x in varBind]

    # 使用Walk拉取数据
    def WalkNumber(self, oid):
        res = []
        for (errorIndication, errorStatus, errorIndex, varBinds) in nextCmd(SnmpEngine(),
             CommunityData(self.region),UdpTransportTarget((self.address, 161)),ContextData(),
             ObjectType(ObjectIdentity(oid)).addMibSource(
             './site-packages/pysnmp/smi/mibs','pysnmp_mibs'),lexicographicMode=False):
            if errorIndication:
                print(errorIndication, file=sys.stderr)
                break
            elif errorStatus:
                print('%s at %s' % (errorStatus.prettyPrint(),
                                    errorIndex and varBinds[int(errorIndex) - 1][0] or '?'),
                      file=sys.stderr)
                break
            else:
                for varBind in varBinds:
                    res.append(str(varBind))
        return res

if __name__ == "__main__":

    # 初始化
    ptr = NetSNMP("192.168.81.130","public")

    # 使用GET方式获取OID数据
    ret = ptr.GetNumber("HOST-RESOURCES-MIB","hrMemorySize",0)
    print("类型: {} --> 返回结果: {} --> 解析: {}".format(type(ret),ret,ret[1]))

    # 使用Walk方式获取OID数据
    ret = ptr.WalkNumber(".1.3.6.1.2.1.2.2.1.6")
    for each in ret:
        mac = each.split("=")[1]
        if len(mac) > 1:
            print("网卡接口: {}".format(mac))