how to allow by MAC
bycn82 at gmail.com
Mon Jun 11 03:16:57 UTC 2012
forget to po the link here
On Mon, Jun 11, 2012 at 11:16 AM, Bill Yuan <bycn82 at gmail.com> wrote:
> Hi Lan,
> Thanks for your reply, I am reading some old emails which you sent in 2008
> while other place asked a same question as mine,
> On Mon, Jun 11, 2012 at 1:53 AM, Ian Smith <smithi at nimnet.asn.au> wrote:
>> In freebsd-questions Digest, Vol 418, Issue 18, Message: 1
>> On Sun, 10 Jun 2012 17:43:39 +0800 Bill Yuan <bycn82 at gmail.com> wrote:
>> > how to allow by MAC in ipfw
>> > currently i set the rule like below
>> > 1 allow ip from any to any MAC any to <MAC Address 1>
>> > 1 allow ip from any to any MAC <MAC Address 1> any
>> > 2 deny all from any to any
>> > i want to only allow the mac address to go through the freebsd
>> > but I found it is not working on my freebsd but it works on pfsense!
>> > so maybe that means the environment is not the same ? and how to setup
>> > ipfw properly to support this ?
>> Bill, you did get some good clues in the earlier thread, but it's not
>> clear if you took note of them. There's also been some confusion ..
>> Firstly, read up on layer2 (ethernet, MAC-level) filtering options in
>> ipfw(8). Thoroughly, several times, until you've got it. Seriously.
>> After enabling sysctl net.link.ether.ipfw=1 (add it to /etc/sysctl.conf)
>> ipfw will be invoked 4 times instead of the normal 2, on every packet.
>> Read carefully ipfw(8) section 'PACKET FLOW', and see that only on the
>> inbound pass invoked from ether_demux() and the outbound pass invoked
>> from ether_output_frame() can you test for MAC addresses (or mac-types);
>> the 'normal' layer3 passes examine packets that have no layer2 headers.
>> You could just add 'layer2' to any rules filtering on MAC addresses, and
>> omit MAC addresses from all layer 3 (IP) rules, but I'd recommend using
>> a method like shown there to separate layer2 and layer3 flows early on:
>> # packets from ether_demux
>> ipfw add 10 skipto 1000 all from any to any layer2 in
>> # packets from ip_input
>> ipfw add 10 skipto 2000 all from any to any not layer2 in
>> # packets from ip_output
>> ipfw add 10 skipto 3000 all from any to any not layer2 out
>> # packets from ether_output_frame
>> ipfw add 10 skipto 4000 all from any to any layer2 out
>> So at (eg) 1000 and 4000 place your incoming and outgoing MAC filtering
>> rules (remembering the reversed order of MAC addresses vs IP addresses,
>> and to allow broadcasts as well), pass good guys and/or block bad guys,
>> then deal with your normal IPv4|v6 traffic in a separate section(s).
>> Or you could just split the flows into two streams, one for layer2 for
>> your MAC filtering, the other for layer3, ie the rest of your ruleset.
>> HTH, Ian [please cc me on any reply]
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