why do we see: "Opcode 6 not implemented"

Danny Thomas D.Thomas at its.uq.edu.au
Sat Aug 18 01:50:55 UTC 2001


our main resolving nameserver (8.2.4) is being hit fairly hard from one client

datagram from [203.101.253.17].464, fd 20, len 99
ns_req: Opcode 6 not implemented
ns_req: answer -> [203.101.253.17].464 fd=20 id=32353 size=12 rc=4


a brief look at
  http://www.iana.org/assignments/dns-parameters
  /usr/include/arpa/nameser.h
  <bind8>/src/include/arpa/nameser.h (bind 9.1 doesn't have similar include)

implies opcode 6 is not defined, though a search throuch recent RFCs is
more difficult: perhaps we should update our
  http://uqnet.its.uq.edu.au/DNS_Resource_Record_Types.html
to include op-codes

the hostname implies it's a mail server and nmap fingerprints it as Win2K
professional

any ideas what's causing this?
[preferably how to restrict them; eg we just added network 10 to this
nameserver to prevent 15 queries a second from another client which is
obviously using network 10 internally but not listing their hosts on their
<cough>bind 4</cough> nameserver]

cheers,
Danny Thomas




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