This is a quick and dirty utility to find up addresses on a `192.168.x.0` subnet like a home LAN.
It will try to guess the subnet if you don't specify an argument. Else the first argument is taken
as the `x` in `192.168.x`.
```python
#!/usr/bin/env python3
import socket
import sys
from subprocess import run, PIPE
from threading import Thread
from time import sleep
import platform

up = set()
hostname = socket.gethostname()

s = platform.system()
if "CYGWIN" in s or "Windows" in s:
  windows = True
else:
  windows = False

if windows:
  def pingcmd(addr):
    return ["ping","-n","1","-w","1",addr]
else:
  def pingcmd(addr):
    return ["ping","-c","1","-w","1",addr]

args = sys.argv[1:]
if len(args) > 0:
  s1 = int(args[0])
else:
  a = socket.getaddrinfo(hostname,80,family=socket.AF_INET)
  subnets = set()
  for x in a:
    y = x[4]
    z = y[0]
    if "192.168" in z:
      r,s,t,u = z.split(".")
      subnets.add(int(t))

  ss = list(sorted(subnets))
  s1 = ss[0]

def tryping(n):
  addr = f"192.168.{s1}.{n}"
  m = run(pingcmd(addr),stdout=PIPE,stderr=PIPE)
  if m.returncode == 0:
    up.add(addr)

for i in range(2,254):
  thread = Thread(target=lambda: tryping(i))
  thread.start()

for i in range(3):
  print(".",end="",file=sys.stderr)
  sys.stderr.flush()
  sleep(1)
print("",file=sys.stderr)
print("\n".join(sorted(up)))
```