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From:SGreen Date:September 1 2005 3:01pm
Subject:Re: Connections with bad DNS cause lockups
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(please, either top-post or bottom-post but don't mix it up)

One way to bypass a broken DNS server is to create complete HOSTS files on 
your servers. That way you can keep using your hostnames but avoid the 
problems of actual DNS server negotiations going sour as all hostname to 
IP address translations are handled locally. This is especially useful for 
resolving internal names for resources that rarely change addresses (like 
servers and most users). Then, the only names that pose a risk would be 
those not on the list.

It's not a perfect solution but it may keep you going until MySQL can 
figure out something better to deal with misbehaving DNS servers.

Shawn Green
Database Administrator
Unimin Corporation - Spruce Pine

Tuc at T-B-O-H <ml@stripped> wrote on 09/01/2005 10:56:24 AM:

> > 
> > Hello.
> > 
> > Have a look here:
> >   http://dev.mysql.com/doc/mysql/en/dns.html
> > 
> > You may want to start mysqld with the --skip-name-resolve option.
> >
> Hi,
> 
> 
>    Thanks for the reply.  I did see that page before, but
> I guess my bigger question is why if the DNS is broken/slow, why
> does the entire server come to a COMPLETE halt, no commands can
> be done via either TCP *OR* the socket.  If it just errored, that
> session took forever, whatever... I could understand. The problem
> is that when it gets probed, it COMPLETELY offlines (DOS) the server.
> And just *1* connection!
> 
>    Just also seems difficult to keep proper documentation if
> we are using IPs and not complete hostnames.
> 
> 
>       Thanks, Tuc
> > 
> > Tuc at T-B-O-H <ml@stripped> wrote:
> > > Hi,
> > > 
> > >        We seem to be running into a problem with our 
> > > installation that we don't understand.
> > > 
> > >        We are running "mysql-server-4.0.25" from
> > > the ports collection on a FreeBSD 5.3-RELEASE-p10
> > > machine. Its tcpwrapper'd to only allow from our
> > > /24, and a single machine outside the /24.
> > > 
> > >        At times, all of a sudden the server seems
> > > to "freeze". It appears that we've narrowed it down
> > > to an issue with people attacking the server that
> > > come from a site that has a bad reverse DNS setup.
> > > 
> > >        Has anyone else seen this, or knows how
> > > to stop it?
> > > 
> > >                Thanks, Tuc
> > > 
> > 
> > 
> > -- 
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> >   /  |/  /_ __/ __/ __ \/ /    Gleb Paharenko
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> >        <___/   www.mysql.com


Thread
Connections with bad DNS cause lockupsTuc at T-B-O-H30 Aug
  • Re: Connections with bad DNS cause lockupsGleb Paharenko31 Aug
    • Re: Connections with bad DNS cause lockupsTuc at T-B-O-H1 Sep
      • Re: Connections with bad DNS cause lockupsSGreen1 Sep
        • Re: Connections with bad DNS cause lockupsTuc at T-B-O-H1 Sep
          • Re: Connections with bad DNS cause lockupsSGreen1 Sep
            • Re: Connections with bad DNS cause lockupsTuc at T-B-O-H1 Sep
      • Re: Connections with bad DNS cause lockupsGleb Paharenko2 Sep
        • Re: Connections with bad DNS cause lockupsTuc at T-B-O-H2 Sep
          • Re: Connections with bad DNS cause lockupsGleb Paharenko3 Sep
            • Re: Connections with bad DNS cause lockupsTuc at T-B-O-H3 Sep
              • Re: Connections with bad DNS cause lockupsGleb Paharenko3 Sep
                • Re: Connections with bad DNS cause lockupsTuc at T-B-O-H3 Sep
                  • Re: Connections with bad DNS cause lockupsGleb Paharenko5 Sep
                    • Re: Connections with bad DNS cause lockupsTuc at T-B-O-H5 Sep
                      • Re: Connections with bad DNS cause lockupsGleb Paharenko5 Sep
                        • Re: Connections with bad DNS cause lockupsTuc at T-B-O-H5 Sep
                    • Re: Connections with bad DNS cause lockupsTuc at T-B-O-H14 Sep