nanog mailing list archives

Re: MACsec SFP


From: Christopher Morrow <morrowc.lists () gmail com>
Date: Wed, 25 Jun 2014 16:45:00 -0400

On Wed, Jun 25, 2014 at 4:17 PM, John Schiel <jschiel () flowtools net> wrote:
Would be nice if we knew what the protocol was that communicated this
information down to the SFP and would also be nice if that was an open
protocol subject to review. UDP something? is my guess but ow do those
messages look?

today you program the key (on switches that do macsec, not in an SFP
that does it for you, cause those don't exist, yet) in your router
config and as near as I have seen there isn't a key distribution
protocol aside from that which you write/manage yourself and which is
likely using ssh/snmp(ick)/telnet(ick).

I'm new to the MACsec idea but I would hope we could watch for such key
exchange traversing the wire and have some method to ignore spurious
messages and keys that may lock up a valid, working SFP.

--John


On Tue, Jun 24, 2014 at 1:27 PM, Pieter Hulshoff <phulshof () aimvalley nl>
wrote:

On 24-06-14 17:50, Christopher Morrow wrote:

So.. now when my SFP in Elbonia dies I need to get a truck to Elbonia
AND it's paired link in west caledonia? yikes. Also, is that a
'ybFxasasdasd' on the serial-number/key-pair-note or ybfXasdadasdsd'
Gosh joe I'm not sure...


Obviously this solution wouldn't work for everyone, but I think for those
people who prefer a simple unmanaged plug-and-play solution it would work
just fine.


 Programmable seems like the way to go, provided there's a path to do
that in the cli of the device you plugged the SFP into? (which I think
is the hard part actually, right?)


Actually, there are many other ways to solve this. If you want unmanaged
still, you could opt for using a key infrastructure combined with 802.1X
EAPOL. For managed solutions, the device could be made programmable via
I2C, in-band from the switch or even in-band from the line. We have several
such managed smart SFPs in our portfolio, so adding such features to this
device will not be a problem. A management channel however is an also added
security risk, so not everybody would be in favour of that. No size fits
all.



On 24-06-14 18:30, Christopher Morrow wrote:

it's going to be hard to schedule a key roll then, right? I would
expect that in most/many deployments where someone enters a 'key'
there has to be some compliance process that includes: "And you change
that key every X days" right? So you'll NOT want to be in a situation
that involves coordinating a few thousand truck rolls every X months
to have this deployed.


True, though an MKA PSK could safely be used for the life-time of a
device. Should one want a regular key roll though, the CAK could be given a
life-time, with a new one distributed automatically via MKA or EAPOL when
it expires. It's also possible to set up a management command to do the
same thing at the operator's request. Plenty of options; I'm trying to find
out what demand there is for each to determine what should make our first
release, and what will not. :)

Kind regards,

Pieter Hulshoff




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