linux系统非ROOT用户80端口不能启动tomcat问题的变通办法——通过Iptables端口转发

2010-07-17 13:21:42 org.apache.tomcat.util.digester.SetPropertiesRule begin 
警告: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'debug' to '0' did not find a matching property. 
2010-07-17 13:21:42  org.apache.catalina.core.AprLifecycleListener init 
信息: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: /usr/jdk1.5.0_16/jre/lib/i386/client:/usr/jdk1.5.0_16/jre/lib/i386:/usr/jdk1.5.0_16/jre/../lib/i386 
2010-07-17 13:21:42  org.apache.coyote.http11.Http11Protocol init 
严重: Error initializing endpoint 
java.net.BindException: Permission denied:80 
        at org.apache.tomcat.util.net.JIoEndpoint.init(JIoEndpoint.java:502) 
        at org.apache.coyote.http11.Http11Protocol.init(Http11Protocol.java:176) 
        at org.apache.catalina.connector.Connector.initialize(Connector.java:1058) 
        at org.apache.catalina.core.StandardService.initialize(StandardService.java:677) 
        at org.apache.catalina.core.StandardServer.initialize(StandardServer.java:795) 
        at org.apache.catalina.startup.Catalina.load(Catalina.java:530) 
        at org.apache.catalina.startup.Catalina.load(Catalina.java:550) 
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) 
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) 
        at java.lang.reflect.Method.invoke(Method.java:585) 
        at org.apache.catalina.startup.Bootstrap.load(Bootstrap.java:260) 
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:412) 
2010-07-17 13:21:43 org.apache.catalina.startup.Catalina load

上面可以看到，非root用户其实没有绑定80端口的权限。在Linux下低于1024的端口是root专用，而Tomcat安装后默认使用用户tomcat启动的，所以将端口改为80后启动，会产生错误：java.net.BindException: Permission denied:80

解决方法是：

第一步，重将Tomcat的端口（server.xml）由80改回8080。

第二步，通过Iptables端口实现80到8080的转发，命令为：

iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 8080

用root用户直接去执行就可以了！

这样，用户访问80端口和8080端口其实都到了8080端口。