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#!/usr/local/bin/python3
print("udp fragments splitted after udp header")
# |----|
# |--------|
import os
from addr import *
from scapy.all import *
pid=os.getpid()
uport=pid & 0xffff
# inetd ignores UDP packets from privileged port or nfs
if uport < 1024 or uport == 2049:
uport+=1024
payload=b"ABCDEFGHIJKLMNOP"
packet=IP(src=LOCAL_ADDR, dst=REMOTE_ADDR)/ \
UDP(sport=uport, dport=7)/payload
frag=[]
fid=pid & 0xffff
frag.append(IP(src=LOCAL_ADDR, dst=REMOTE_ADDR, proto=17, id=fid,
flags='MF')/bytes(packet)[20:28])
frag.append(IP(src=LOCAL_ADDR, dst=REMOTE_ADDR, proto=17, id=fid,
frag=1)/bytes(packet)[28:44])
eth=[]
for f in frag:
eth.append(Ether(src=LOCAL_MAC, dst=REMOTE_MAC)/f)
if os.fork() == 0:
time.sleep(1)
sendp(eth, iface=LOCAL_IF)
os._exit(0)
ans=sniff(iface=LOCAL_IF, timeout=3, filter=
"ip and src "+REMOTE_ADDR+" and dst "+LOCAL_ADDR+" and udp")
for a in ans:
if a and a.type == ETH_P_IP and \
a.payload.proto == 17 and \
a.payload.frag == 0 and a.payload.flags == 0 and \
a.payload.payload.sport == 7:
port=a.payload.payload.dport
print("port=%d" % (port))
if port != uport:
print("WRONG UDP ECHO REPLY PORT")
exit(2)
data=a.payload.payload.payload.load
print("payload=%s" % (data))
if data == payload:
exit(0)
print("PAYLOAD!=%s" % (payload))
exit(1)
print("NO UDP ECHO REPLY")
exit(2)
|
