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Date: Mon, 21 Apr 2014 19:34:12 +0400
From: "Andrey V. Elsukov" <ae@FreeBSD.org>
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To: bycn82 <bycn82@gmail.com>
Subject: Re: how does it pass in the rule sets
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On 21.04.2014 19:14, bycn82 wrote:
> On 4/21/14 22:34, Andrey V. Elsukov wrote:
>> On 19.04.2014 11:45, bycn82 wrote:
>>> Hi,
>>> can someone help to explain how does the user land command `ipfw` pass
>>> the rule set into the hook function in the kernel? I assume that it must
>>> be hardcoded in somewhere, but I did not find it yet.
>> ipfw(8) uses raw socket and setsockopt(2)/getsockopt(2) functions to
>> interact with kernel. In particular, do_cmd() function from ipfw2.c does it.
>>
> Thanks very much,
> Actually I saw the source already, the ipfw_ctl() method. I would like
> to call it as "an event handler"
> But why it will triggered?  where are the code to register this method
> as listener?
> Sorry for using Java terminologies ;)

You need to improve your grep-fu :)

When you load ipfw.ko kernel module, vnet_ipfw_init() initializes
V_ip_fw_ctl_ptr = ipfw_ctl.

When you call setsockopt() for raw socket, it invokes ctloutput method
for RAW IP - rip_ctloutput() (netinet/raw_ip.c). It calls ipfw_ctl() via
V_ip_fw_ctl_ptr pointer.

-- 
WBR, Andrey V. Elsukov