Index: pcap.py
===================================================================
--- pcap.py	(revision 57)
+++ pcap.py	(working copy)
@@ -132,13 +132,15 @@
 
     def loop(self, callback, *args):
         self.dispatch(0, callback, *args)
    
     def __iter__(self):
         self.__f.seek(FileHdr.__hdr_len__)
         while 1:
             buf = self.__f.read(PktHdr.__hdr_len__)
             if not buf: break
             hdr = self.__ph(buf)
+            if hdr.caplen > self.__fh.snaplen:
+                raise Exception("Packet is bigger than snaplen (%d > %d)" % (hdr.caplen, self.__fh.snaplen))
             buf = self.__f.read(hdr.caplen)
             yield (hdr.tv_sec + (hdr.tv_usec / 1000000.0), buf)