A netgraph question.
jdp at elvis.rowan.edu
Sat Nov 1 15:15:36 PDT 2008
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
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
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.
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