介绍
SNMP代表简单网络管理协议。这是服务器可以共享有关其当前状态的信息的一种方式，也是管理员可以修改预定义值的渠道。SNMP 是在网络堆栈的应用层上实现的协议（单击此处了解网络层）。该协议的创建是为了以一致的方式从非常不同的系统收集信息。
您可以在上面的链接中阅读有关SNMP、OID和SNMP 方法的更多信息。作为总结，该脚本使用：
- snmp 版本 2c
- snmpwalk作为主要的snmp获取数据的方法
- 从设备获取的数据是从特定的OID获取的（更多 LLDP OID 可以在这里找到）
链路层发现协议 ( LLDP ) 是供应商中立的第 2 层协议，连接到特定 LAN 段的站点可以使用该协议来通告其身份和功能，并从物理上相邻的第 2 层对等方接收相同信息。
使用python结合SNMP和LLDP
我的程序的目的是通过使用Python3.6并提供一个交换机数据文件（社区字符串，snmp端口和交换机ip），返回所有交换机的邻居数据（本地和远程端口+邻居的名称）在文件中。
示例配置文件：
community_string1, snmp_port1, ip1
community_string2, snmp_port2, ip2
community_string3, snmp_port3, ip3
示例输出：
[
{
"name1": {
"ip": "ip1",
"neighbours": [
{
"neighbour_name1": "neighbour_name1",
"local_port1": "local_port1",
"remote_port1": "remote_port1"
},
{
"neighbour_name2": "neighbour_name2",
"local_port2": "local_port2",
"remote_port2": "remote_port2"
},
{
"neighbour_name3": "neighbour_name3",
"local_port3": "local_port3",
"remote_port3": "remote_port3"
},
]
},
"name2": {data here},
"name3": {data here},
}
]
解释输出
name1表示配置文件第一行中的交换机名称（通过执行 snmp walk for 检索PARENT_NAME_OID）ip1从配置文件的第一行表示交换机的ip（这是从配置文件中获取的）- 邻居都是使用特定的 OID 通过 snmp 检索的（见下面的代码）。
我认为这种 JSON 输出格式是最相关的，但如果您有更好的想法，我很想听听。
编码
现在，代码有点乱，但它使用pysnmp可以通过pip. 它接收配置文件作为 CLI 参数，解析它并处理其中的信息。
import argparse
import itertools
import os
import pprint
from pysnmp.hlapi import *
NEIGHBOUR_PORT_OID = '1.0.8802.1.1.2.1.4.1.1.8.0'
NEIGHBOUR_NAME_OID = '1.0.8802.1.1.2.1.4.1.1.9'
PARENT_NAME_OID = '1.0.8802.1.1.2.1.3.3'
class MissingOidParameter(Exception):
"""
Custom exception used when the OID is missing.
"""
pass
def is_file_valid(filepath):
"""
Check if a file exists or not.
Args:
filepath (str): Path to the switches file
Returns:
filepath or raise exception if invalid
"""
if not os.path.exists(filepath):
raise ValueError('Invalid filepath')
return filepath
def get_cli_arguments():
"""
Simple command line parser function.
"""
parser = argparse.ArgumentParser(description="")
parser.add_argument(
'-f',
'--file',
type=is_file_valid,
help='Path to the switches file'
)
return parser
def get_switches_from_file():
"""Return data as a list from a file.
The file format is the following:
community_string1, snmp_port1, ip1
community_string2, snmp_port2, ip2
community_string3, snmp_port3, ip3
The output:
[
{"community": "community_string1", "snmp_port": "snmp_port1", "ip": "ip1"},
{"community": "community_string2", "snmp_port": "snmp_port2", "ip": "ip2"},
{"community": "community_string3", "snmp_port": "snmp_port3", "ip": "ip3"},
]
"""
args = get_cli_arguments().parse_args()
switches_info = []
with open(args.file) as switches_info_fp:
for line in switches_info_fp:
line = line.rstrip().split(',')
switches_info.append({
'community': line[0].strip(),
'snmp_port': line[1].strip(),
'ip': line[2].strip(),
})
return switches_info
def parse_neighbours_ports_result(result):
"""
One line of result looks like this:
result = iso.0.8802.1.1.2.1.4.1.1.8.0.2.3 = 2
Where the last "2" from the OID is the local port and the value
after '=' is the remote port (2)
"""
if not result:
raise MissingOidParameter('No OID provided.')
value = result.split(' = ')
if not value:
return 'Missing entire value for OID={}'.format(result)
else:
oid, port = value
local_port = re.search(r'{}\.(\d+)'.format(NEIGHBOUR_PORT_OID[2:]), oid).group(1)
if port:
remote_port = re.search(r'(\d+)', port).group(1)
else:
remote_port = 'Unknown'
return 'local_port', local_port, 'remote_port', remote_port
def parse_parent_name(result):
"""
One line of result looks like this:
result = iso.0.8802.1.1.2.1.3.3.0 = Switch01
The name of the parent is "Switch01"
"""
if not result:
raise MissingOidParameter('No OID provided.')
value = result.split(' = ')
if not value:
return 'Missing entire value for OID={}'.format(result)
else:
return 'Unknown' if not value[-1] else value[-1]
def parse_neighbour_names_results(result):
"""
One line of result looks like this:
result = iso.0.8802.1.1.2.1.4.1.1.9.0.2.3 = HP-2920-24G
The name of the parent is "Switch01"
"""
if not result:
raise MissingOidParameter('No OID provided.')
value = result.split(' = ')
if not value:
return 'Missing entire value for OID={}'.format(result)
else:
return ('name', 'Unknown') if not value[-1] else ('name', value[-1])
def main():
data = {}
switches_filedata = get_switches_from_file()
for switch in switches_filedata:
community = switch.get('community')
snmp_port = switch.get('snmp_port')
ip = switch.get('ip')
name = ''
for (error_indication, error_status, error_index, var_binds) in nextCmd(
SnmpEngine(),
CommunityData(community),
UdpTransportTarget((ip, snmp_port)),
ContextData(),
ObjectType(ObjectIdentity(PARENT_NAME_OID)),
lexicographicMode=False
):
# this should always return one result
name = parse_parent_name(str(var_binds[0]))
if not name:
print('Could not retrieve name of switch. Moving to the next one...')
continue
neighbour_names = []
neighbour_local_remote_ports = []
for (error_indication, error_status, error_index, var_binds) in nextCmd(
SnmpEngine(),
CommunityData(community),
UdpTransportTarget((ip, snmp_port)),
ContextData(),
ObjectType(ObjectIdentity(NEIGHBOUR_NAME_OID)),
lexicographicMode=False
):
for var_bind in var_binds:
neighbour_names.append(
parse_neighbour_names_results(str(var_bind))
)
for (error_indication, error_status, error_index, var_binds) in nextCmd(
SnmpEngine(),
CommunityData(community),
UdpTransportTarget((ip, snmp_port)),
ContextData(),
ObjectType(ObjectIdentity(NEIGHBOUR_PORT_OID)),
lexicographicMode=False
):
for var_bind in var_binds:
neighbour_local_remote_ports.append(
parse_neighbours_ports_result(str(var_bind))
)
neighbours = []
for a, b in itertools.zip_longest(
neighbour_names,
neighbour_local_remote_ports,
fillvalue='unknown'
):
neighbours.append({
a[0]: a[1],
b[0]: b[1],
b[2]: b[3]
})
data[name] = {
'ip': ip,
'neighbors': neighbours
}
return data
if __name__ == '__main__':
all_data = main()
pprint.pprint(all_data, indent=4)
snmp-lldp.py -f snmp-lldp.txt