Linux下防火墙开启相关端口及查看已开启端口

最近利用Apache Mina实现了一个http服务，发布到linux下发现无法访问，通过HttpClient来发送http请求时，报如下错误：

Exception in thread "main" org.apache.http.conn.HttpHostConnectException: Connection to http://10.5.20.96:8011 refused

    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:190)

    at org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:294)

    at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:640)

    at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:479)

    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:906)

    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:1066)

    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:1044)

    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:1035)

    at com.tudou.findlabel.entrance.ClientWithResponseHandler.main(ClientWithResponseHandler.java:52)

Caused by: java.net.ConnectException: Connection refused: connect

    at java.net.PlainSocketImpl.socketConnect(Native Method)

    at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)

    at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)

    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)

    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)

    at java.net.Socket.connect(Socket.java:519)

    at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:127)

    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180)

    ... 8 more

原来是因为linux下没有开启对8011的端口访问权限造成的。通过下面的命令可以开启允许对外访问的网络端口：

/sbin/iptables -I INPUT -p tcp --dport 8011 -j ACCEPT #开启8011端口
/etc/rc.d/init.d/iptables save #保存配置
/etc/rc.d/init.d/iptables restart #重启服务
查看端口是否已经开放
/etc/init.d/iptables status
结果如下