Loop through values and compare

[edroche3rd]

Hi everyone

My 2nd inquiry as I try to learn Python and ways to expand my network engineering toolkit.

I found a script on Packetswitch by Suresh Vina where he connects to a router gets its arp table then connects to a switch and grabs its mac table. Then compares the 2 lists and match mac to switch interface. I am trying to work off of that and take a list of known mac addresses in a csv file and compare to the mac table of a switch. I am able to pull the mac addresses from the csv file and also able to connect to the switch and get the mac table. The issue I am running into is the comparing part. The script runs through with no errors but just not giving me the print statements I am looking for at the end. Below is what I have so far. Any suggestions much appriciated!

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File Contents 50:00:00:0E:80:02 50:00:00:0B:00:00

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Script from napalm import get_network_driver import getpass import json import csv     #User Input user = input(">> Username: ") passw = getpass.getpass(">> Password: ") host = input(">> Hostname: ") os_type = input(">> OS Type, example - cisco_ios, nxos, etc: ") mac_add = open("mac_data.csv", "r") print(mac_add.read())   net_driver = get_network_driver(os_type)   #Switch Connection Dict network_device = {     "hostname": host,     "username": user,     "password": passw       }     #Switch Connection device = net_driver(**network_device) device.open()   device_mac = device.get_mac_address_table() print(json.dumps(device_mac, indent=4))     for each_mac in mac_add:     if mac_add in device_mac_list[n]["mac"]:         print(f'{device_mac} is connected to {network_device["hostname"]} on {device_mac[n]["interface"]} ')     else:         print(f'{device_mac} not found!')

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Output >> Username: admin >> Password: >> Hostname: 172.31.2.2 >> OS Type, example - cisco_ios, nxos, etc: ios 50:00:00:0E:80:02 50:00:00:0B:00:00   [     {         "mac": "50:00:00:03:00:02",         "interface": "Gi0/3",         "vlan": 2,         "static": false,         "active": true,         "moves": -1,         "last_move": -1.0     },     {         "mac": "50:00:00:03:00:2F",         "interface": "Gi0/3",         "vlan": 2,         "static": false,         "active": true,         "moves": -1,         "last_move": -1.0     },     {         "mac": "50:00:00:0A:00:00",         "interface": "Gi1/0",         "vlan": 2,         "static": false,         "active": true,         "moves": -1,         "last_move": -1.0     },     {         "mac": "50:00:00:0B:00:00",         "interface": "Gi0/3",         "vlan": 2,         "static": false,         "active": true,         "moves": -1,         "last_move": -1.0     },     {         "mac": "50:00:00:03:00:02",         "interface": "Gi0/3",         "vlan": 3,         "static": false,         "active": true,         "moves": -1,         "last_move": -1.0     } ]

[deanhystad]

When you did this:

1	print(mac_add.read())

You read the enire file. When you get here:

1	for each_mac in mac_add:

You are already at the end of the file. The loop doesn't run at all.

That really doesn't matter though, because your approach was not going to work anyway.

I think you should get the device mac address table and convert it to a dictionary. It is currently a list of dictionaries.

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from napalm import get_network_driver import getpass     # Make dictionary of networks keyed by mac network_device = {     "hostname": input(">> Hostname: "),     "username": input(">> Username: "),     "password": getpass.getpass(">> Password: "), } net_driver = get_network_driver(input(">> OS Type, example - cisco_ios, nxos, etc: ")) device = net_driver(**network_device) device.open() mac_dictionary = {d["mac"]: d for d in device.get_mac_address_table()}     with open("mac_data.csv", "r") as file:     for mac in file:         mac = mac.strip()         if network := mac_dictionary.get(mac):             print(                 f'{mac} is connected to {network_device["hostname"]} on {network["interface"]} '             )         else:             print(f"{mac} not found!")

[edroche3rd]

Hi Dean

Thanks that worked like a charm. In the below line what are the "d" for?

Sorry for what might be a dumb question but still trying to learn.

Thanks
Ed

1	mac_dictionary = {d["mac"]: d for d in device.get_mac_address_table()}

[deanhystad]

That is a dictionary comprehension.

[edroche3rd]

Thank you...one last question

Where does "network" come from in the following line? I don't see it defined anywhere.

1	if network := mac_dictionary.get(mac):

Thanks

[deanhystad]

That is where it is defined. := is an assignment operator, like =. The difference is := can be used in an expression.

1	if network := mac_dictionary.get(mac):

This is the same as:

1 2	network = mac_dictionary.get(mac) if network:

[edroche3rd]

ok I see thanks again!