mysql over TCP and far out PIDs

[David Thornton]

Is it possible your grant tables don't have any entries for the host that
you look like you are connecting from?
Secure by default?

David


On Wed, Feb 19, 2014 at 10:59 PM, Jamon Camisso
<jamon.camisso-H217xnMUJC0sA/PxXw9srA at public.gmane.org>wrote:

> On 19/02/14 04:30 PM, Darryl Moore wrote:
> > coool, I never knew about ss. Thx.
> >
> > Using it I see:
> > # ss -l -n -p | grep mysql
> > LISTEN  0   50    *:3306          *:*      users:(("mysqld",9248,10))
> >
> > Which matches the PID and shows mysql is listening
> > # ps ax | grep mysql
> >  9248 ?        Ssl    0:02 /usr/sbin/mysqld
> >  9310 pts/1    S+     0:00 tail -f /var/log/mysql/error.err
> > 10691 pts/2    S+     0:00 grep --color=auto mysql
> >
> > Yeah.
> >
> > But I still get that error when I try to log in via TCP
>
> Are you using mysql -h 127.0.0.1 -u user dbname to login? Telnet is only
> able to report what MySQL tells it, which is that it is listening on
> 127.0.0.1:3306 and that MySQL has closed the connection in your example
> below.
>
> I would use a proper MySQL client, even if telnet seems good enough.
>
> > It's not a mysql user permission issue. Besides the fact that all
> > servers are set up the same, I can telnet into that port with two very
> > different results.
> >
> > # telnet 127.0.0.1 3306
> > Trying 127.0.0.1...
> > Connected to 127.0.0.1.
> > Escape character is '^]'.
> > Connection closed by foreign host.
> >
> > Boom. She dies right away on my broken machines, but on the one that
> > works, get this:
> >
> > telnet localhost 3306
> > Trying 127.0.0.1...
> > Connected to localhost.
> > Escape character is '^]'.
> > [
> > 5.5.35-0ubuntu0.12.04.2T� JL{J?>X � 6/(vA~wZ;Z2+mysql_native_password
> >
> > ...so it wants a password which is what I world expect.
> >
> >
> > So why does mysql listen on the port but then immediately close the
> > connection?
>
> Have you tried on ::1 - I'm not sure how MySQL works with IPv6, but if
> you don't specify an address, and MySQL does indeed have IPv6 enabled,
> you could try that as a different method to to test connections to
> localhost. Check your /etc/hosts and you'll see that localhost resolves
> to both 127.0.0.1 and ::1 depending on if traffic is IPv4 or IPv6.
>
> Again, I do not know if MySQL does IPv6 by default.
>
> You could also bind to another interface and try that.
>
> Eliminate localhost/127.0.0.1/::1 altogether and try binding to an
> address on a temporary private VLAN and see if that works. It should not
> until you explicitly grant permission.
>
> > Looking further with tcpdump I see the following on the server that
> works.
> <snip>
> > Very baffling. Thanks for all the responses so far, and the corrections
> > on using netstat. I'll continue looking into this. Any other insights
> > would be most welcome.
>
> Last question: firewall? If iptables is involved, what do: 'iptables
> -nvL' and 'iptables -t nat -nvL' show?
>
> Cheers, Jamon
> --
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