Python3使用snmp获取H3C交换机arp表

修改为真实的 ip、只读团体字、oid，如`entaddr = walk("100.50.1.1", "test@123", oTable["H3CARP"])`

```python
# -*- coding:utf-8 -*-
import sys
import time

#snmp协议获取h3c核心交换机arp表，保存到txt文件
#运行用时50秒左右
#有时会报错提示超时,多运行几次会好

try:
    from pysnmp.entity.rfc3413.oneliner import cmdgen
except Exception as e:
    print("You need to download pysnmp and pyasn1", e)
    sys.exit(1)

oTable = {
    "entLogicalCommunity": (1, 3, 6, 1, 2, 1, 47, 1, 2, 1, 1, 4),
    "entPhysicalModelName": (1, 3, 6, 1, 2, 1, 47, 1, 1, 1, 1, 13, 1),
    "entLogicalDescr": (1, 3, 6, 1, 2, 1, 47, 1, 2, 1, 1, 2),
    "dot1dBasePort": (1, 3, 6, 1, 2, 1, 17, 1, 4, 1, 1),
    "dot1dTpFdbPort": (1, 3, 6, 1, 2, 1, 17, 4, 3, 1, 2),
    "dot1dBasePortIfIndex": (1, 3, 6, 1, 2, 1, 17, 1, 4, 1, 2),
    "dot1dTpFdbAddress": (1, 3, 6, 1, 2, 1, 17, 4, 3, 1, 1),
    "ifDescr": (1, 3, 6, 1, 2, 1, 2, 2, 1, 2),
    "ifName": (1, 3, 6, 1, 2, 1, 31, 1, 1, 1, 1),
    "ifSpeed": (1, 3, 6, 1, 2, 1, 2, 2, 1, 5),
    "ifAlias": (1, 3, 6, 1, 2, 1, 31, 1, 1, 1, 18),
    "sysName": (1, 3, 6, 1, 2, 1, 1, 5, 0),
    "sysDescr": (1, 3, 6, 1, 2, 1, 1, 1, 0),
    "dot3StatsDuplexStatus": (1, 3, 6, 1, 2, 1, 10, 7, 2, 1, 19),
    "ifAdminStatus": (1, 3, 6, 1, 2, 1, 2, 2, 1, 7),
    "ifOperStatus": (1, 3, 6, 1, 2, 1, 2, 2, 1, 8),
    "atPhysAddress": (1, 3, 6, 1, 2, 1, 3, 1, 1, 2),
    "ipAdEntAddr": (1, 3, 6, 1, 2, 1, 4, 20, 1, 1),
    "ipAdEntIfIndex": (1, 3, 6, 1, 2, 1, 4, 20, 1, 2),
    "ARP": (1, 3, 6, 1, 2, 1, 3, 1, 1, 2),
    "HW": (1, 3, 6, 1, 2, 1, 4, 22, 1, 2),
    "H3CARP": (1, 3, 6, 1, 2, 1, 4, 22, 1, 2)
}

#[[ObjectType(ObjectIdentity(<ObjectName value object, tagSet <TagSet object, tags 0:0:6>, payload [1.3.6.1.2.1.4.22...18636.10.100.1.1]>), <OctetString value object, tagSet <TagSet object, tags 0:0:4>, subtypeSpec <ConstraintsIntersection object, consts <ValueSizeConstraint object, consts 0, 65535>>, encoding iso-8859-1, payload [0x00900b6fbd60]>)],
#
# [ObjectType(ObjectIdentity(<ObjectName value object, tagSet <TagSet object, tags 0:0:6>, payload [1.3.6.1.2.1.4.22...18636.10.100.1.2]>), <OctetString value object, tagSet <TagSet object, tags 0:0:4>, subtypeSpec <ConstraintsIntersection object, consts <ValueSizeConstraint object, consts 0, 65535>>, encoding iso-8859-1, payload [0xecd68a19a852]>)]]

#[['10.100.1.1', '0x00900b6fbd60'], ['10.100.1.2', '0xecd68a19a852']]

def walk(dswitch, commVlan, oid  ):
    """This function will return the table of OID's that I am walking"""
    errorIndication, errorStatus, errorIndex, \
        generic = cmdgen.CommandGenerator().nextCmd(cmdgen.CommunityData('my-agent', commVlan, 1), \
        cmdgen.UdpTransportTarget((dswitch, 161)), oid, maxRows=10000)

try:
        if errorIndication or errorStatus or errorIndex:
            print(errorIndication, errorStatus, errorIndex, generic)
    except:
        return errorIndication
    return generic

# if errorIndication:
    #     print(generic)
    #     return errorIndication
    # return generic

# entaddr = walk("100.50.37.50", "public", oTable["ARP"])
entaddr = walk("100.50.1.1", "test@123", oTable["H3CARP"])
print(str(entaddr), type(entaddr))  #type=list
if str(entaddr) == "No SNMP response received before timeout":
    print("超时前未收到SNMP响应")
else:
    arp_table = []

for i in entaddr:
        temp = ''
        for j in i:
            print(str(j))  # SNMPv2-SMI::mib-2.4.22.1.2.18636.10.100.1.1 = 0x00900b6fbd60
            temp += str(j)
        #print(temp)  # SNMPv2-SMI::mib-2.4.22.1.2.18636.10.100.1.1 = 0x00900b6fbd60
        #time.sleep(9999)

#replace() 方法把字符串中的 old（旧字符串） 替换成 new(新字符串)，如果指定第三个参数max，则替换不超过 max 次。
        temp = temp.replace("SNMPv2-SMI::mib-2.4.22.1.2.", "")
        temp = temp[temp.find('.')+1:]
        temp = temp.split(' = ')
        arp_table.append(temp)

#print(arp_table)
    with open('ipmac_str.txt', 'a', encoding='utf-8') as df:
        for i in arp_table:
            mywr = '='.join(i)
            df.write(mywr)
            df.write('\n')
```

生成的ipmac_str.txt内容格式如下
```python
192.168.1.231=0x005056839497
192.168.1.232=0x005056837450
192.168.1.233=0x005056835e89
```