SNMPv3 Engine ID Discovery

SNMP v3 introduces the concept of the Engine ID, a unique identifier for each SNMP agent in the network.

Gufo SNMP automatically performs Engine ID discovery as needed. However, you can retrieve the actual value for various purposes, such as inventory management or performance optimization, and use it to skip the discovery step later.

import sys

from gufo.snmp import User
from gufo.snmp.sync_client import SnmpSession


def main(addr: str, user_name: str) -> None:
    with SnmpSession(addr=addr, user=User(user_name)) as session:
        engine_id = session.get_engine_id()
        print(engine_id.hex())


main(sys.argv[1], sys.argv[2])

Let's see the details.

import sys

from gufo.snmp import User
from gufo.snmp.sync_client import SnmpSession


def main(addr: str, user_name: str) -> None:
    with SnmpSession(addr=addr, user=User(user_name)) as session:
        engine_id = session.get_engine_id()
        print(engine_id.hex())


main(sys.argv[1], sys.argv[2])

Import sys module to parse the CLI argument.

Warning

We use sys.argv only for demonstration purposes. Use argsparse or alternatives in real-world applications.

import sys

from gufo.snmp import User
from gufo.snmp.sync_client import SnmpSession


def main(addr: str, user_name: str) -> None:
    with SnmpSession(addr=addr, user=User(user_name)) as session:
        engine_id = session.get_engine_id()
        print(engine_id.hex())


main(sys.argv[1], sys.argv[2])

We need to import an User class.

import sys

from gufo.snmp import User
from gufo.snmp.sync_client import SnmpSession


def main(addr: str, user_name: str) -> None:
    with SnmpSession(addr=addr, user=User(user_name)) as session:
        engine_id = session.get_engine_id()
        print(engine_id.hex())


main(sys.argv[1], sys.argv[2])

SnmpSession object holds all necessary API. We're using a synchronous version from gufo.snmp.sync_client.

import sys

from gufo.snmp import User
from gufo.snmp.sync_client import SnmpSession


def main(addr: str, user_name: str) -> None:
    with SnmpSession(addr=addr, user=User(user_name)) as session:
        engine_id = session.get_engine_id()
        print(engine_id.hex())


main(sys.argv[1], sys.argv[2])

We define our main function and expect the following arguments:

• Address of the agent.
• Valid user name.

import sys

from gufo.snmp import User
from gufo.snmp.sync_client import SnmpSession


def main(addr: str, user_name: str) -> None:
    with SnmpSession(addr=addr, user=User(user_name)) as session:
        engine_id = session.get_engine_id()
        print(engine_id.hex())


main(sys.argv[1], sys.argv[2])

First, we need to create SnmpSession object which wraps the client's session. The SnmpSession may be used as an instance directly or operated as context manager using the with clause. When used as a context manager, the client automatically closes all connections on the exit of context, so its lifetime is defined explicitly.

SnmpSession constructor offers lots of configuration variables for fine-tuning. Refer to the SnmpSession reference for further details. In our example, we set the agent's address and create SNMPv3 user with default settings.

Note

To perform Engine ID discovery, the only mandatory parameter is the username. Authentication and privacy settings can be left at their default values.

import sys

from gufo.snmp import User
from gufo.snmp.sync_client import SnmpSession


def main(addr: str, user_name: str) -> None:
    with SnmpSession(addr=addr, user=User(user_name)) as session:
        engine_id = session.get_engine_id()
        print(engine_id.hex())


main(sys.argv[1], sys.argv[2])

SnmpSession.get_engine_id() returns discovered Engine Id as bytes.

import sys

from gufo.snmp import User
from gufo.snmp.sync_client import SnmpSession


def main(addr: str, user_name: str) -> None:
    with SnmpSession(addr=addr, user=User(user_name)) as session:
        engine_id = session.get_engine_id()
        print(engine_id.hex())


main(sys.argv[1], sys.argv[2])

Now, we print the collected Engine ID. Since it is of bytes type, we convert the output to hexadecimal form, which is commonly used in network equipment configuration.

import sys

from gufo.snmp import User
from gufo.snmp.sync_client import SnmpSession


def main(addr: str, user_name: str) -> None:
    with SnmpSession(addr=addr, user=User(user_name)) as session:
        engine_id = session.get_engine_id()
        print(engine_id.hex())


main(sys.argv[1], sys.argv[2])

Lets run our main() function and pass first command-line parameters as address, community, and OID.

Running

Let's check our script. Run example as:

$ python3 examples/sync/engine-id-discovery.py 127.0.0.1 user1
8000b85c03ec02732921c0