My connection to a remote server on a local network kept failing. Of course the problem was iptables. The error for MySQL was an error code 113.
iptables -I RH-Firewall-1-INPUT -p tcp –dport 3306 -j ACCEPT
iptables -I RH-Firewall-1-INPUT -p udp –dport 3306 -j ACCEPT
I’d forgotten to set my ip tables:
http://eduardo-lago.blogspot.jp/2012/02/installing-nfs-on-centos-62.html
So my NFS shares weren’t working.
This was a useful page:
http://qugstart.com/blog/linux/centos-nfs-how-to-guide-exporting-and-mounting-a-nfs-drive/
I found in a cluster of machines that I couldn’t access MySQL remotely anymore. After some playing around with GRANT PRIVILEGES in MySQL, I realised that the issue wasn’t actually because of the MySQL settings at all.
So, was it the port number that I was connecting to that happened to be wrong?
netstat -tln | grep 3306
Showed that MySQL is running on port 3306 as intended.
telnet xx.xx.xx.xx 3306
From machine A to machine B refused to accept connections, so I knew that we had an issue somewhere else – probably on the firewall – stopping me from connecting remotely.
I didn’t really have much experience with iptables, so had to read a little bit more into it. Firstly, I needed to display all the rules on the firewall with this command:
/sbin/iptables -L -v -n
…under the Chain RH-Firewall-1-INPUT I saw no mention of the open port 3306 for MySQL. We needed to add two rules, for tcp and udp connections.
/sbin/iptables -I RH-Firewall-1-INPUT -p tcp –dport 3306 -j ACCEPT
/sbin/iptables -I RH-Firewall-1-INPUT -p udp –dport 3306 -j ACCEPT
Afterwards, I was able to connect remotely to the MySQL machine again.