import dpkt,sys
import re
import itertools

fd = open(sys.argv[1])
pcap = dpkt.pcap.Reader(fd)
trg = '\xcax\x07\xd3'
data = ''
urps = []
idx = 0 
for ts, buf in pcap:
    eth = dpkt.ethernet.Ethernet(buf)
    ip = eth.data
    tcp = ip.data
    if ip.src != trg:
        continue
        
    if tcp.flags & dpkt.tcp.TH_URG:
        print idx,tcp.urp,len(tcp.data)
        data += tcp.data
        
    idx+=1
    
with open('/tmp/orig.txt') as f:
    d = f.read()

orig = d.split()
new  = data.split()
f= lambda idx: filter(lambda x: x[0] != x[1],zip(new[idx],itertools.cycle(orig[idx])))[0][0]

diffs = filter(lambda x: not x[1],enumerate(map(lambda x: x[0]==x[1],zip(new,orig))))[:24]
print ''.join(map(lambda i:f(i),map(lambda x:x[0],diffs)))