#!/usr/local/bin/python2.7 # old fragment completely overlaps new one # |------------| # |XXXX| # |----| # If the current fragment is completely overlapped by existing ones, # drop the newer fragment. # if (precut >= frent->fe_len) # goto bad_fragment; # 'Nearer' traffic wins. import os from addr import * from scapy.all import * dstaddr=sys.argv[1] pid=os.getpid() & 0xffff payload="ABCDEFGHIJKLOMNOQRSTUVWX" dummy="01234567" packet=IP(src=SRC_OUT, dst=dstaddr)/ICMP(id=pid)/payload frag0=str(packet)[20:28] frag1=dummy frag2=str(packet)[28:52] pkt0=IP(src=SRC_OUT, dst=dstaddr, proto=1, id=pid, frag=0, flags='MF')/frag0 pkt1=IP(src=SRC_OUT, dst=dstaddr, proto=1, id=pid, frag=2, flags='MF')/frag1 pkt2=IP(src=SRC_OUT, dst=dstaddr, proto=1, id=pid, frag=1)/frag2 eth=[] eth.append(Ether(src=SRC_MAC, dst=PF_MAC)/pkt2) eth.append(Ether(src=SRC_MAC, dst=PF_MAC)/pkt1) eth.append(Ether(src=SRC_MAC, dst=PF_MAC)/pkt0) if os.fork() == 0: time.sleep(1) sendp(eth, iface=SRC_IF) os._exit(0) ans=sniff(iface=SRC_IF, timeout=3, filter= "ip and src "+dstaddr+" and dst "+SRC_OUT+" and icmp") a=ans[0] if a and a.type == ETH_P_IP and \ a.payload.proto == 1 and \ a.payload.frag == 0 and a.payload.flags == 0 and \ icmptypes[a.payload.payload.type] == 'echo-reply': id=a.payload.payload.id print "id=%#x" % (id) if id != pid: print "WRONG ECHO REPLY ID" exit(2) load=a.payload.payload.payload.load print "payload=%s" % (load) if load == payload: exit(0) print "PAYLOAD!=%s" % (payload) exit(1) print "NO ECHO REPLY" exit(2)