setip.py

'''
  a python script to set a static IPv4 address to a network interface but first checks if its unique 
  by doing an ARP probe.
'''

from scapy.all import * 
import socket, fcntl
import os
import argparse

def set_if_addr(iface, ip):
    SIOCSIFADDR = 0x8916
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    bin_ip = socket.inet_aton(ip) 
    ifreq = struct.pack('16sH2s4s8s', bytes(iface, 'utf-8'), socket.AF_INET, b'\x00'*2, bin_ip, b'\x00'*8) 
    fcntl.ioctl(sock, SIOCSIFADDR, ifreq)

def is_ipaddr_used(ip):
    ether = Ether() 
    probe = Ether(src=ether.src, dst='ff:ff:ff:ff:ff:ff')/ARP(op=1, hwsrc=ether.src, pdst=ip) 
    resp = srp(probe, timeout=2, verbose=False)[0] 
    return len(resp) != 0

parser = argparse.ArgumentParser(
        prog = 'ssetip', 
        description='sets a static ip address but first checks if its not used by doing an arp probe')

parser.add_argument('-ip', "--ip")
parser.add_argument('-if', "--iface")
args = parser.parse_args() 

if is_ipaddr_used(args.ip):
    print(f"[+] {args.ip} is used")
else:
    print(f"[+] {args.ip} is unique ...\n[+] Setting {args.iface} address to {args.ip}")
    set_if_addr(args.iface, args.ip)