[SOLVED] MySQL Remote access forbidden only to a specific client

zhjim · 01-22-2014, 02:09 AM

The telnet approach in http://www.linuxquestions.org/questi...4/#post5102200 shows that the mysql server can be reached. So it must be something else. Also the access tables are fine.

MAybe just to make sure: create a new database, create a new user with explicit ip settings thats only allowed to access that db, try to connect. The ip should be of the host that has the problem.

romagnolo · 01-22-2014, 03:40 AM

Solved!

I considered the hypothesis of a dumb NAT which couldn't support more than one connection per source/destination pair, so I opened two concurrent instances of mysql-client on a generic VM (as in diagram), but they worked fine. Also I disabled the slave MySQL server, then rebooted the DSL 'router', but still from the slave host I couldn't reach the master.

Then I tcpdump-ed the client, just to find that it was dialoguing in "full duplex" with master, so there didn't appear to be a connection block along the chain.

Finally, I spotted an odd inconsistency within slave's /etc/mysql/my.cfn, which was:

Code:

[client]
port            = 3307
socket          = /var/run/mysqld/mysqld.sock

so the cmd-line client launched from the slave host was attempting to reach the master from a nonstandard port, hence got rejected without much eloquent explanation, requiring wild guesses.

The port was so configured a long while ago to allow another instance of MySQL to run on a different VM within the same OpenVZ host. AFAIR the MySQL instances were in port conflict, even if they run on separate VMs.