一、查看防火墙开放了那些端口。
如下：22,3306已经对外开放了
[root@localhost tomcat7]# /etc/init.d/iptables status Table: filter Chain INPUT (policy ACCEPT) num target prot opt source destination 1 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED 2 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 3 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 4 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22 5 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:3306 6 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited Chain FORWARD (policy ACCEPT) num target prot opt source destination 1 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited Chain OUTPUT (policy ACCEPT) num target prot opt source destination
二、提示防火墙已经关闭了。
[root@localhost bin]# /etc/init.d/iptables status iptables: Firewall is not running.
三、开放某个端口，如8080端口，
1、直接编辑/etc/sysconfig/iptables ，内容中新增一条
-A INPUT -m state --state NEW -m tcp -p tcp --dport 端口号 -j ACCEPT
注意位置需要放在-A INPUT -j REJECT --reject-with icmp-host-prohibited前面。
[root@localhost /]# vi /etc/sysconfig/iptables # 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 8080 -j ACCEPT -A INPUT -j REJECT --reject-with icmp-host-prohibited -A FORWARD -j REJECT --reject-with icmp-host-prohibited COMMIT
2、重新启动防火墙服务 service iptables restart
[root@localhost bin]# service iptables restart iptables: Setting chains to policy ACCEPT: filter [ OK ] iptables: Flushing firewall rules: [ OK ] iptables: Unloading modules: [ OK ] iptables: Applying firewall rules: [ OK ]
四、直接关闭或打开防火墙（处于安全考虑不建议）
1) 重启后生效
开启： chkconfig iptables on 关闭： chkconfig iptables off
2) 即时生效，重启后失效
开启： service iptables start 关闭： service iptables stop
附带，测试能不能访问某个端口是，可以用telnet命令，telnet host port 如：telent 192.168.101.11 8080
如果telent命令不能识别，需要通过命令yum install telnet安装 （CentOS系统），windows 环境自行百度 下。
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