Can anyone tell me why my web server cannot connect to a DB server?

Question

"Can't connect to MYSQL server" error. The DB is a separate server. http://dpaste.com/99702/

I typed "nc dbserver 3306" and it returned: [XXXXXX] 3306 (mysql) : Connection refused

Even in my GRANT options, I specified GRANT ALL TO . %...

My friend said that the web server is being prevented from establishing a TCP connection of any kind to that port.

I checked my.cnf...nothing special there. Could it be because of my IPTABLES? --skip-networking option is NOT in my.cnf.

Thank you

Answer 1

111 usually is a generic "socket" connect error, i.e. the packet never made it there. Without more info about how your firewall is set up, it could be caused by:

• Bad IP address
• Bad Port number (no service is running at that port)
• Bad routing setup (rare, but happens)
• Firewall is absorbing or rejecting the packet. This is most likely.

Try connecting with a firewall exception and see if that works. The exception should allow all traffic between the IP addresses of both machines, so there will be two rules - one for ingress and one for egress.

Answer 2

Connection refused means it's not listening on your external IP address. I know you said you'd looked at your my.cnf, but make sure you do not have any of the following lines:

bind-address            = 127.0.0.1
skip-networking

If you have bind-address, change it to be

bind-address            = *

If you have skip-networking, remove it.

If you've done these things, then check your firewall.

Answer 3

First thing to check : try to connect on the PC with MySQL.

Here's what I'd do to check where the error comes from :

1. Try to connect directly : mysql -h 127.0.0.1 -u [username] -p[password]
2. Try to connect directly with the external IP and the command line still on the MySQL computer : mysql -h 192.168.0.26 -u [username] -p[password]
3. Try to connect using command line from a distinct PC : mysql -h 192.168.0.26 -u [username] -p[password]
4. If everything works, the problems comes from the Apache Server configuration. Otherwise you'll be able to quickly guess where the problem comes from.

Answer 4

First and foremost, ensure that your MySQL server is actually listening on an external TCP socket. Do a netstat and see if you get something with 3306 in it and make sure that it is not just 127.0.0.1:3306 or something local like that.

# netstat -untap | grep 3306

Sometimes, MySQL is by default configured to listen only on local sockets. If that is the case, just edit your my.cnf file to listen on all interfaces. Otherwise, it is likely a networking problem.