Python 封裝SNMP呼叫介面

PySNMP 是一個純粹用Python實現的SNMP,用PySNMP的最抽象的API為One-line Applications,其中有兩類API：同步的和非同步的,都在模組pysnmp.entity.rfc3413.oneliner.cmdgen 中實現,如下是Get方式與Walk方式的基本實現.

首先需要在系統中安裝SNMP使用者端,對於Linux平臺來說只需要執行如下設定過程即可.

[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系統則需要在客戶機服務列表，開啟SNMP支援，並設定好一個團體名稱，如下圖。

當我們設定好使用者端後，伺服器端就客戶獲取資料了，我們以一個OID序號為例，我們查詢特定序號對應的名稱，然後將其記錄下來，例如下面這樣。

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

首先我們不使用PySNMP模組直接開執行緒呼叫看看,該程式碼如下所示.

import os,re,time

# 通過SNMP收集主機CPU利用率: 通過SNMP協定,收集目標主機的CPU利用率(百分比),並返回JSON字串.
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

# 通過SNMP獲取系統CPU負載資訊: 分別獲取到系統的1,5,15分鐘的負載資訊,並返回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

# 通過SNMP獲取系統記憶體佔用: 記憶體利用率，獲取到之後，將其轉化為字典格式儲存。
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

# 通過SNMP獲取系統磁碟資料: 這個案例並不完整,我只寫了一點,後面有個問題一直沒有解決.
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)

我們使用pysnmp模組來做，安裝pysnmp很簡單，執行命令pip install pysnmp 即可，安裝後使用以下程式碼執行即可獲取到目標資料，獲取方式分為兩種一種為Get另一種為Walk.

from pysnmp.hlapi import *
import os,sys

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

    # 獲取指定資料的方法
    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拉取資料
    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方式獲取OID資料
    ret = ptr.GetNumber("HOST-RESOURCES-MIB","hrMemorySize",0)
    print("型別: {} --> 返回結果: {} --> 解析: {}".format(type(ret),ret,ret[1]))

    # 使用Walk方式獲取OID資料
    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("網路卡介面: {}".format(mac))