Python 3.7.4 : Test the DHCP handshakes.

First, the DHCP is based on the earlier BOOTP protocol which uses well-known port numbers for both server and client instead of an ephemeral port. The server and the client communicate via broadcast and the server broadcasts the offered IP address to the client on UDP port 68.
This python example has a learning purpose and does not harm anyone.

import subprocess as sub
import re

def find_word(w):
    return re.compile(r'\b({0})\b'.format(w), flags=re.IGNORECASE).search

p = sub.Popen(('sudo', 'tcpdump', '-l', '-s 0', '-vvv', '-n', '((udp port 67) and (udp[8:1] = 0x1))'),
 stdout=sub.PIPE)
for row in iter(p.stdout.readline, b''):
    if find_word(row):
        print (row.split(' ')[-1])
    elif find_word(row):
        print (row.split(' ')[-1])

The result of my script ( I don't have inputs on this port).

[mythcat@desk scripts]$ python3 dhcpreq.py 
tcpdump: listening on ___, link-type EN10MB (Ethernet), capture size 262144 bytes
^CTraceback (most recent call last):
  File "dhcpreq.py", line 10, in 
    for row in iter(p.stdout.readline, b''):
KeyboardInterrupt
0 packets captured
0 packets received by filter
0 packets dropped by kernel
[mythcat@desk scripts]$ vim dhcpreq.py