启用IPTables后，局域网上的MySQL无法正常工作

我有两个Centos VM。

IP地址如下：

• VM_1 => 10.99.0.10
• VM_2 => 10.99.0.12

Apache和PHP在VM_1中，而MySQL在VM_2中。两者都有iptables规则。VM_2使用规则正常。现在，我正在从VM_1进行测试。

首先，我禁用了 VM_1 iptables并连接到VM_2 MySQL（已成功连接）。

[root@foster ~]# service iptables stop
iptables: Applying firewall rules:                         [  OK  ]
[root@foster ~]# mysql -h 10.99.0.12 -u root -p
Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 16
Server version: 5.6.21 MySQL Community Server (GPL)
...

其次，我启用了 VM_1 iptables并连接到VM_2 MySQL（它也从未在数小时之内响应）。

[root@foster ~]# service iptables start
iptables: Applying firewall rules:                         [  OK  ]
[root@foster ~]# mysql -h 10.99.0.12 -u root -p
Enter password:

我的iptables规则有什么问题？这是我的iptables规则：

[root@foster ~]# iptables -L
Chain INPUT (policy DROP)
target     prot opt source               destination
ACCEPT     all  --  anywhere             anywhere
ACCEPT     icmp --  anywhere             anywhere            icmp echo-reply
ACCEPT     icmp --  anywhere             anywhere            icmp echo-request
ACCEPT     udp  --  anywhere             anywhere            udp spt:domain
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:ssh state N                                                     EW,ESTABLISHED
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:http state                                                      NEW,ESTABLISHED
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:https state                                                      NEW,ESTABLISHED
ACCEPT     tcp  --  10.99.0.12           anywhere            tcp dpt:mysql state                                                      NEW,ESTABLISHED
ACCEPT     tcp  --  localhost            anywhere            tcp dpt:mysql state                                                      NEW,ESTABLISHED
LOGGING    all  --  anywhere             anywhere

Chain FORWARD (policy DROP)
target     prot opt source               destination
ACCEPT     all  --  anywhere             anywhere

Chain OUTPUT (policy DROP)
target     prot opt source               destination
ACCEPT     all  --  anywhere             anywhere
ACCEPT     icmp --  anywhere             anywhere            icmp echo-request
ACCEPT     icmp --  anywhere             anywhere            icmp echo-reply
ACCEPT     udp  --  anywhere             anywhere            udp dpt:domain
ACCEPT     tcp  --  anywhere             anywhere            tcp spt:ssh state E                                                     STABLISHED
ACCEPT     tcp  --  anywhere             anywhere            tcp spt:http state                                                      ESTABLISHED
ACCEPT     tcp  --  anywhere             anywhere            tcp spt:https state                                                      ESTABLISHED
ACCEPT     tcp  --  anywhere             anywhere            tcp spt:mysql state                                                      ESTABLISHED
ACCEPT     tcp  --  anywhere             anywhere            tcp spt:mysql state                                                      ESTABLISHED

Chain LOGGING (1 references)
target     prot opt source               destination
LOG        all  --  anywhere             anywhere            limit: avg 2/min bu                                                     rst 5 LOG level debug prefix `IPTables Dropped -:- '
DROP       all  --  anywhere             anywhere

问题是您不允许建立与MySQL的新连接，并且将sport和dport颠倒了：

Chain INPUT (policy DROP)
...
ACCEPT     tcp  --  10.99.0.12 anywhere  tcp dpt:mysql state   NEW,ESTABLISHED
ACCEPT     tcp  --  localhost  anywhere  tcp dpt:mysql state   NEW,ESTABLISHED
...

Chain OUTPUT (policy DROP)
...
ACCEPT     tcp  --  anywhere   anywhere  tcp spt:mysql state   ESTABLISHED
ACCEPT     tcp  --  anywhere   anywhere  tcp spt:mysql state   ESTABLISHED
...

正确的iptables -L输出应该是：

Chain INPUT (policy DROP)
...
ACCEPT     tcp  --  10.99.0.12 anywhere  tcp spt:mysql state   ESTABLISHED
ACCEPT     tcp  --  localhost  anywhere  tcp spt:mysql state   ESTABLISHED
...

Chain OUTPUT (policy DROP)
...
ACCEPT     tcp  --  anywhere   anywhere  tcp dpt:mysql state   NEW,ESTABLISHED
ACCEPT     tcp  --  anywhere   anywhere  tcp dpt:mysql state   NEW,ESTABLISHED
...