A netgraph question.

Bryant Eadon bryant.eadon at gmail.com
Sat Nov 1 16:23:30 PDT 2008

Bryant Eadon wrote:
> Joe Pellegrino wrote:
>  OK so here it goes. I actually have two seperate questions involving
>> netgraph, I am new to this subject so please bare with me. If there is 
>> a better way to achieve these goals too, please suggest them but I 
>> think netgraph is the way to go.
>> The first part involves allowing a userland program to communicate 
>> with a kernel module, similar to how netlink works in Linux. The 
>> second part involves intercepting network packets and possibly 
>> manipulating them before they are allowed to proceed, similar to how 
>> netfilter works. I believe I can do both of these with the netgraph 
>> (ng_socket and possibly ng_ether). I haven't looked closely at 
>> ng_ether yet so I'll focus on ng_socket.
>> I have been able to create a ng_socket (Control and Data) using the 
>> socket call as described in "All About NetGraphs" and the man page. 
>> I've also been able to 'name' the node using bind. I was able to 
>> verify this using ngctl. I know (from the man page) I should 
>> eventually be able to send/receive using the sendto/recvfrom functions 
>> once the connection is established. But beyond this I don't know how 
>> to proceed. So the question is what are the next steps. For example:
>> Although I see a named netgraph node there are no hooks. ng_socket 
>> says it supports an arbitrary number of hooks so how do I create the 
>> hooks? Then of course how do I connect them.
>> Of course I realize that I proabably need to create a node on the 
>> kernel side so which type of netgraph node would be suggested? How is 
>> it created and then hooked to the ng_socket?
>> Again I am looking to allow some IPC between a userland program and a 
>> kernel module similar to the Linux netlink. I've been through most man 
>> pages and can't seem to find a lot of good documentation or example 
>> code so I am hoping to get some pointers here. BTW If this is the 
>> wrong list please directly to the right place to ask. Thanks in advance.
>> ---jdp
> Have you looked into how "systat -ifstat" works ?

Whoops.  Wrong thread.  Please ignore.

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