In Linux, you may encounter minor problems when configuring the firewall to enable port 80 and port 3306.

In Linux, you may encounter minor problems when configuring the firewall to enable port 80 and port 3306.
Zookeeper

Vi/etc/sysconfig/iptables

-A input-m state-state NEW-m tcp-p tcp-dport 80-j ACCEPT (allow port 80 to pass the firewall)
-A input-m state-state NEW-m tcp-p tcp-dport 3306-j ACCEPT (allow port 3306 to pass the firewall)
Note:

Many users add these two rules to the last line of the firewall configuration, resulting in firewall startup failure. The correct rule should be added to the default port 22.

The firewall rules are as follows:

######################################
# Firewall configuration written by system-config-firewall
# Manual customization of this file is not recommended.
* Filter
: Input accept [0: 0]
: Forward accept [0: 0]
: Output accept [0: 0]
-A input-m state-state ESTABLISHED, RELATED-j ACCEPT
-A input-p icmp-j ACCEPT
-A input-I lo-j ACCEPT
-A input-m state-state NEW-m tcp-p tcp-dport 22-j ACCEPT
-A input-m state-state NEW-m tcp-p tcp-dport 80-j ACCEPT
-A input-m state-state NEW-m tcp-p tcp-dport 3306-j ACCEPT
-A input-j REJECT-reject-with icmp-host-prohibited
-A forward-j REJECT-reject-with icmp-host-prohibited
COMMIT
#####################################

/Etc/init. d/iptables restart
# Restart the firewall to make the configuration take effect.

This article mainly records possible problems. As I encountered this problem, I put the newly added rules on the last line of the configuration file, which causes mysql to be unable to access remotely.