Best way to inject packets into linux kernel to emulate ethernet packet arrival

Question

I am writing a linux kernel module for some tunnelling activity. The module will get packets from the networking stack and perform some operations on it. What is the best possible way to inject packets into the stack from the bottom(emulate ethernet packet arrival on wire) so that the packet traverses the entire receive path and is delivered to my module.

My module uses the kernel br_handle_frame_hook hook to get the packet which means that it cannot co-reside with the linux native bridge module. Any ideas will be appreciated.

Answer 1

Consider using NetFilter

http://www.phrack.org/issues.html?issue=61&id=13

TAP would be great, if you're working in user space, which you're not

Answer 2

我相信您正在寻找TAP设备-一种从用户空间发送/接收以太网数据包的好方法

Answer 3

I recommend tap like @raber before me. I also recommend reading this excelet tutorial: http://backreference.org/2010/03/26/tuntap-interface-tutorial/ .

You asked whether you can make the tap non-programatically and then replay traffic into it. The answer is yes. Look for the 'persistency' options (which btw can also be done programatically with a short tool you can write yourself if you prefer not to download tools that can already do it). You may also want/need to define the user that may use the tap (or otherwise just sudo your operations).