Read-Only Connection Pattern

import os
from getpass import getpass
from netmiko import ConnectHandler
from netmiko.exceptions import (
    NetmikoAuthenticationException,
    NetmikoTimeoutException,
    ReadTimeout,
)

device = {
    "device_type": "cisco_ios",
    "host": "192.0.2.10",
    "username": os.environ.get("NETMIKO_USERNAME") or input("Username: "),
    "password": os.environ.get("NETMIKO_PASSWORD") or getpass("Password: "),
    "secret": os.environ.get("NETMIKO_ENABLE_SECRET"),
    "conn_timeout": 10,
    "auth_timeout": 20,
    "banner_timeout": 15,
    "read_timeout_override": 30,
}

try:
    with ConnectHandler(**device) as conn:
        if device.get("secret") and not conn.check_enable_mode():
            conn.enable()
        output = conn.send_command("show ip interface brief", read_timeout=30)
        print(output)
except NetmikoAuthenticationException:
    print("Authentication failed")
except NetmikoTimeoutException:
    print("SSH connection timed out")
except ReadTimeout:
    print("Command read timed out")

Use placeholder addresses from documentation ranges in examples. Keep real inventory in an ignored local file or a secrets-managed system.

Batch Collection

from concurrent.futures import ThreadPoolExecutor, as_completed
from typing import Any

def collect_show(device: dict[str, Any], command: str) -> dict[str, Any]:
    host = device["host"]
    try:
        with ConnectHandler(**device) as conn:
            output = conn.send_command(command, read_timeout=45)
        return {"host": host, "ok": True, "output": output}
    except (NetmikoAuthenticationException, NetmikoTimeoutException, ReadTimeout) as exc:
        return {"host": host, "ok": False, "error": type(exc).__name__}

results = []
with ThreadPoolExecutor(max_workers=8) as pool:
    futures = [pool.submit(collect_show, device, "show version") for device in devices]
    for future in as_completed(futures):
        results.append(future.result())

Keep max_workers low unless the device estate and AAA systems are known to handle higher connection volume.

Structured Parsing

Netmiko can ask TextFSM, TTP, or Genie to parse supported command output. Treat parser output as an optimization, not the only evidence path.

with ConnectHandler(**device) as conn:
    parsed = conn.send_command(
        "show ip interface brief",
        use_textfsm=True,
        raise_parsing_error=False,
        read_timeout=30,
    )

if isinstance(parsed, str):
    print("No parser template matched; store raw output for review")
else:
    for row in parsed:
        print(row)

If parsing drives a blocking decision, keep the raw command output alongside the parsed result so an operator can inspect mismatches.

Guarded Config Pattern

import os

commands = [
    "interface GigabitEthernet0/1",
    "description CHANGE-1234 UPLINK-TO-CORE",
]

…

sec-netexec-mcp

通过 SSH 在 Kali 上执行 NetExec 渗透测试命令，辅助网络安全评估与协议探测。