NXOS ARP to IP Lookup

nxos_arp_ip_lookup.py

'''
Quick and dirty MAC address to IP address lookup tool. Creates CSV compliant data. A total hack done in 15 minutes, saving HOURS of work.

In the mac_table.txt, have a list of mac addresses from 'show mac address-table'. Remove the headers.

192.168.148.31   00:08:17  0050.56b9.dddd  Vlan128         
192.168.148.146  00:01:45  8c60.4f54.eeee  Vlan128         
192.168.144.32   00:17:08  0050.56b9.ffff  Vlan134         
192.168.144.21   00:00:41  0050.56bb.gggg  Vlan104   

In your port_sw.txt file, grab the ARP entries from 'show ip arp'. Remove the headers. 
* 379      0014.4ff9.2ccc    dynamic   0          F    F  Eth115/1/20
* 442      4cd9.8f64.8aaa    dynamic   0          F    F  Eth113/1/19
* 442      4cd9.8f64.9122    dynamic   200        F    F  Eth115/1/11

When you run the program, it outputs a CSV that you can throw into Excel to create a cut sheet. Includes port, mac, VLAN and IP.

Eth125/1/4,0014.4ffb.ddd2,128,192.168.128.12
Eth135/1/6,5cf3.fcea.ccc2,128,192.168.128.95
Eth101/1/42,a4bf.0137.bbbc,128,192.168.128.229
Eth165/1/12,b026.28e5.abcd,128,192.168.128.59
'''

# Open the MAC list and parse it first
with open("mac_table.txt") as mac_file:
    mac_entries = mac_file.readlines()

# Create a temp dictionary for the contents of the MAC table.
mac_dict = {}
# Iterate through each line, reading it into the table. Set the mac_dict key to temp[2] (the MAC) and temp[0] to the IP address.
for line in mac_entries:
    temp = str.split(line)
    mac_dict[temp[2]] = temp[0]

######################

# Open the port list and parse it first
with open('port_sw.txt') as port_file:
    port_entries = port_file.readlines()

# Iterate through each port
for port in port_entries:
    temp = str.split(port)
    # Lookup MAC address in the mac_dict dict - this goes in a try/except block because there are certain ports that don't have IPs. If that happens, just put a '-' in the entry
    try:
        ip_addr = mac_dict[temp[2]]
    except:
        ip_addr = '-'
    # Physical port, MAC address, VLAN, IP address (or a - if one doesn't exist). Prints this out to the console.
    print(f"{temp[7]},{temp[2]},{temp[1]},{ip_addr}")