PROBLEM
You added rules for mysql to iptables and it is still not working. Mysql traffic is still blocked.
SOLUTIONS
Make sure the order of rules is correct. Any rule that you add must be inserted before the REJECT rule. Iptables does not process further rules after REJECT rule.
EXAMPLE
You entered:
iptables -A INPUT -p tcp -s YOUR.SOURCE.IP.HERE --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -p tcp --sport 3306 -m state --state ESTABLISHED -j ACCEPT
You should have entered
iptables -I INPUT 1 -p tcp -s YOUR.SOURCE.IP.HERE --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -I OUTPUT 1 -p tcp --sport 3306 -m state --state ESTABLISHED -j ACCEPT
Notice the number after INPUT, thats the number of an existing rule. Your rule will be inserted before this rule.
use -I to insert your rule before rule
use -A to append rules to end of iptables rules
OTHER HELPFUL INFO
Command to list iptable rules with line numbers
iptables -vnL --line-numbers
Command to delete iptables rules
iptables -D (CHAIN NAME HERE: INPUT,OUTPUT or FORWARD) (RULE NUMBER HERE)
example: iptables -D INPUT 6
Command to save iptables after editing on CentOS/REHL
/sbin/service iptables save
Command to restart iptables service and apply changes on CentOS/REHL
service network restart
