bind 8.2.2-p5 ns_req errors with connection refused.

[Mark.Andrews at nominum.com]

> foo at foobar.org wrote:
> 
> > Hey, all.
> >
> > I keep getting ns_req connection refused messages like:
> >
> > messages.Dec1899.gz:Dec 17 17:18:36 www5 named[5484]: ns_req:
> > sendto([192.168.254.192].2653): Connection refused
> > messages.Dec1899.gz:Dec 17 17:18:36 www5 named[5484]: ns_req:
> > sendto([192.168.254.209].1489): Connection refused
> > messages.Dec1899.gz:Dec 17 17:18:36 www5 named[5484]: ns_req:
> > sendto([192.168.253.244].1829): Connection refused
> >
> > My version of bind is 8.2.2-p5 and it works fine, but at times (at what
> > seems to be random times) I will  get this error message and the DNS
> > server doesn't respond.
> >
> > The only way I have found to fix it is to send a HUP to the named or
> > wait an undetermined amount of time for it to work again (it's
> > undetermined, because I send a HUP as more then 5 minutes and management
> > would be on my tail)
> >
> > So any insight of why the DNS server is stalling would be appreciated.
> 
> Sorry I can't offer anything specific, but this looks more like a system
> problem than a BIND bug. sendto() is a fairly low-level networking routine,
> and "Connection refused" is something the networking stack returns. Perhaps
> you are exhausting some sort of resource on the machine, which goes away
> temporarily when you reload named (?). How does the machine look otherwise?
> 
> 
	'sentto' on linux returns a error when the socket has received a
	ICMP port unreachable message.  Most other stacks only return this
	message when the socket is 'connected'.

	As for why named stalled, I suspect that it was the result of
	syslog stalling.  On most platforms syslog does not block.  Linux
	implementations block unless recent patches have been applied.

	By the time you see these error messages the stall had ended as these
	are the result of send messages to clients that have timed out and
	closed their UDP socket.

	Mark
--
Mark Andrews, Nominum Inc. / Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at nominum.com