1#!/usr/local/bin/python2.7 2 3print "udp fragments splitted after udp header" 4 5# |----| 6# |--------| 7 8import os 9from addr import * 10from scapy.all import * 11 12pid=os.getpid() 13uport=pid & 0xffff 14# inetd ignores UDP packets from privileged port or nfs 15if uport < 1024 or uport == 2049: 16 uport+=1024 17payload="ABCDEFGHIJKLMNOP" 18packet=IP(src=LOCAL_ADDR, dst=REMOTE_ADDR)/ \ 19 UDP(sport=uport, dport=7)/payload 20frag=[] 21fid=pid & 0xffff 22frag.append(IP(src=LOCAL_ADDR, dst=REMOTE_ADDR, proto=17, id=fid, 23 flags='MF')/str(packet)[20:28]) 24frag.append(IP(src=LOCAL_ADDR, dst=REMOTE_ADDR, proto=17, id=fid, 25 frag=1)/str(packet)[28:44]) 26eth=[] 27for f in frag: 28 eth.append(Ether(src=LOCAL_MAC, dst=REMOTE_MAC)/f) 29 30if os.fork() == 0: 31 time.sleep(1) 32 sendp(eth, iface=LOCAL_IF) 33 os._exit(0) 34 35ans=sniff(iface=LOCAL_IF, timeout=3, filter= 36 "ip and src "+REMOTE_ADDR+" and dst "+LOCAL_ADDR+" and udp") 37for a in ans: 38 if a and a.type == ETH_P_IP and \ 39 a.payload.proto == 17 and \ 40 a.payload.frag == 0 and a.payload.flags == 0 and \ 41 a.payload.payload.sport == 7: 42 port=a.payload.payload.dport 43 print "port=%d" % (port) 44 if port != uport: 45 print "WRONG UDP ECHO REPLY PORT" 46 exit(2) 47 data=a.payload.payload.payload.load 48 print "payload=%s" % (data) 49 if data == payload: 50 exit(0) 51 print "PAYLOAD!=%s" % (payload) 52 exit(1) 53print "NO UDP ECHO REPLY" 54exit(2) 55