packet too big

[G. Roderick Singleton]

On Fri, 2004-07-09 at 10:46, Michael Varre wrote:
> > -----Original Message-----
> > From: bind-users-bounce at isc.org [mailto:bind-users-bounce at isc.org] On
> > Behalf Of Joel
> > Sent: Friday, July 09, 2004 10:43 AM
> > To: Michael Varre
> > Cc: bind-users at isc.org
> > Subject: Re: packet too big
> > 
> > 
> > 
> > Michael Varre wrote:
> > > > I noticed that when using my name servers as a resolver I cannot get
> > > > to several yahoo sites.  I dug in and noticed a message is getting
> > > > logged on the firewall that the packet is over 512 bytes (this is the
> > > > answer packet).
> > > > The answer seems to be coming directly from yahoo's name servers. I
> > > > have included captures.  One is from an answer I receive from
> > > > roadrunner ns and the other is from one of my resolvers.  There is
> > > > clearly more data at the end of mine, however I have no clue why it is
> > > > there from my server rather than others.
> > > >
> > > >
> > > >
> > > > Any ideas on this problem would be greatly appreciated!  Thanks!
> > 
> > As you have noticed this is a firewall issue and is best addressed
> > at that point in the chain. On my PIX we do this
> > 
> > 	fixup protocol dns maximum-length 1024
> > 
> > Check your docs for what you need to do to let EDNS0 packets get through
> > the firewall.
> > - Joel
> > 
> 
> 
> Joel, 
> Well yes that is one possibility. However it seems to me that there is no
> good reason for the packet to be larger than 512bytes - 512 is pretty
> standard.  I don't see how my setup could be different from most other
> servers on the net.
> 
> mv

I suggest that you are blocking tcp packets which are used when the
returned information is larger than a udp packet.
-- 
G. Roderick Singleton <gerry at pathtech.org>
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