[Dshield] Port 16 traffic

Rob packethunter at comcast.net
Fri Dec 23 23:41:03 GMT 2005

jmulkerin wrote:
> We're just getting hammered with fragmented traffic to port 16 on a 
> dns/smtp server.  Its always 1 packet.  Normally he/she sends two 
> packets and changes IPs then two more, then changes IP .etc.  Here is a 
> snippet:
> [Root]system-critical-00440: Fragmented traffic! From 
> to DNSSERVER:16, proto UDP (zone Untrust, int 
> ethernet1). Occurred 1 times. (2005-12-23 07:18:39)
> We have nothing running on port 16 and haven't found any covert channels 
> running on port 16.
> Comments?
> John Mulkerin
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Have you captured any of the packets?  tcpdump or Ethereal would be great.
Typically, if a packet is fragmented, only the first "piece" will have 
port numbers.  All subsequent fragments will retain the same packet ID, 
but only have payload above the IP layer (no TCP or UDP headers).


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