What is Port Triggering?

If you have not read my explanation of port forwarding do so now. You can find it
here.

Port triggering is pretty simple once you know what port forwarding is. Port Triggering is port forwarding with an on/off switch for the ports that have been forwarded. This on/off switch is turned on or off by data flowing out of a trigger port.

Let's say that there is a port triggering rule configured in the router. This port triggering rule says when data flows out on port 50 forward port 80. In the picture above you see data flowing from a computer to the internet on port 50.

The router see's the traffic coming out of the router on port 50, and evaluates it's triggering rules. The router then forwards port 80 to the computer that sent out the data on port 50. It's important to realize that port 80 can only be forwarded to one
computer at a time. If two computers were trying to send data out on port 50, there would be a conflict. What happened after that really depends upon which router you are running. One thing is for sure, port 80 would not be forwarded to both computers.

The picture above shows that the data has quit being sent out of port 50. Programs do not send data if there is nothing to be sent, so data being sent out of port 50 is not guaranteed. The router keeps port 80 forwarded for a certain amount of time. How
much time really depends upon the router.

Once the router is done waiting, it quits forwarding port 80 to the computer that sent data out on port 50. This makes a port triggering configuration a tricky thing. The software that requires ports to be forwarded must first send data out of a port at
a somewhat constant rate. If the software has a port that is constantly sending data out, then port triggering is possible. The length of time that the router keeps those ports open still needs to be taken into account. If the router times out between the
gaps of outgoing data, the port forwarding connection will be severed. That is why so few programs support port triggering. What happens when you are trying todownload a very large file? Well the software you have setup port triggering for may not keep sending
data out of the trigger port.If it doesn't your router closes the incoming ports, and your download is interrupted.

Port Triggering is a little more secure than port forwarding, because the incoming ports are not open all the time. They are only open when a program is actively using the trigger port. Another thing to note, is that most port triggering setups do not require
you to enter an internal ip address to forward the incoming ports to. This means that any computer on the network can use your port triggering setup. If two computers try to use the port triggering setup at the same time you will run into problems.

路由器port触发与转发---Port Forwarding & Port Triggering的更多相关文章

  1. NAT&Port Forwarding&Port Triggering

    NAT     Nat,网络地址转换协议.主要功能是实现局域网内的本地主机与外网通信.     在连接外网时,内部Ip地址须要转换为网关(一般为路由器Ip地址)(port号也须要对应的转换)     ...

  2. Why was 80 Chosen as the Default HTTP Port and 443 as the Default HTTPS Port?

    https://www.howtogeek.com/233383/why-was-80-chosen-as-the-default-http-port-and-443-as-the-default-h ...

  3. shell脚本检查是否存在tun0虚拟网卡,若不不存在服务器更改port,并重启服务器,客户端修改port,并重新启动客户端

    openvp 客户端 /home 目录下各脚本文件名 [root@jira home]# ls openvpn_server_restart.sh openvpn_tunnel_monitor.sh ...

  4. TCP的三次握手和四次挥手与路由器(三层)转发原理

    传输层是国际标准化组织提出的开放系统互连(OSI)参考模型中的第四层.该层协议为网络端点主机上的进程之间提供了可靠.有效的报文传送服务.其功能紧密地依赖于网络层的虚拟电路或数据报服务.传输层定义了主机 ...

  5. Hbase启动的时候出现:[RpcServer.handler=28,port=60000] ipc.RpcServer: RpcServer.handler=28,port=60000: exiting,master.HMasterCommandLine: Master exiting

    hadoop 版本:CDH5.02 Hbase 版本:hbase-0.96.1.1-cdh5.0.2 配置文件:hbase-site.xml <configuration> <pro ...

  6. H3C 路由器单播IP包转发

  7. NAT&Port Forwarding&Port Triggering

    NAT     Nat,网络地址转换协议.主要功能是实现局域网内的本地主机与外网通信.     在连接外网时,内部Ip地址需要转换为网关(一般为路由器Ip地址)(端口号也需要相应的转换)     如: ...

  8. Port Forwarding in Windows

    转自:http://woshub.com/port-forwarding-in-windows/ Since Windows XP there is a built-in ability in Mic ...

  9. Port forwarding with xinetd Ask

    https://stackoverflow.com/questions/21716673/port-forwarding-with-xinetd --------------------------- ...

随机推荐

  1. HTML/CSS方法实现下拉菜单

    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/ ...

  2. java回调简单实现

    package data; import java.util.HashMap; import java.util.Map; public class Good { CallBack callBack; ...

  3. vue 不能监测数组长度变化length的原因

    由于 JavaScript 的限制,Vue 不能检测以下变动的数组: 当你利用索引直接设置一个项时,例如:vm.items[indexOfItem] = newValue 当你修改数组的长度时,例如: ...

  4. Vue 作用域插槽

    使用场景:复用子组件的slot,又可以使slot的内容不一样. <!DOCTYPE html> <html lang="zh"> <head> ...

  5. 05-hibernate注解-多对一单向外键关联

    多对一单向外键 1,多方持有一方的引用,比如:多个学生对应一个班级(多对一) 2,@ManyToOne(cascade={CascadeType.ALL},  fetch=FetchType.EAGE ...

  6. CentOS下febootstrap自制Docker的CentOS6.6和7.1 Docker镜像

    docker image centos febootstrap CentOS 6.6和7.1 Docker自制CentOS镜像 安装: ? 1 yum -y install febootstrap 添 ...

  7. (一)Lucene——基本概念介绍

    1. Lucene是什么 Lucene 是一个基于 Java 的全文信息检索工具包,它不是一个完整的搜索应用程序,而是为你的应用程序提供索引和搜索功能.Lucene 目前是 Apache Jakart ...

  8. Windows 10 KMS 激活方法

    本篇文章由:http://xinpure.com/windows-10-activate-method/ 摘抄: http://www.nruan.com/win-key.html 须知:如果需要在线 ...

  9. Fragment的陷阱

    以前做过的一个项目,Fragment嵌套高德地图,当再次进入Fragment的时候,会出现奇怪的现象.嵌套的地图会出现滑动不动的情况,起先还以为是高德的bug呢,经过一番研究,终确定这是一个坑. 先对 ...

  10. win8安装Visual C++ 2015 build tools闪退解决办法

    win8安装Visual C++ 2015 build tools闪退解决办法 安装Visual Studio 2015闪退问题也同样应用此解决办法. 1.控制面板——添加删除程序——启动关闭wind ...