Hi Phil,
Thanks - I 100% understand the point of best practice of not using
maxLength and the potential for hijacking, what im most worried about is
the statement i've been told about 'unused' ROAs affecting used ROAs,
which just seems counter-intuitive to me, in terms of (as per the
example given) having ROAs ready for failover or TE purposes.
This is the RFC im referring to:
https://datatracker.ietf.org/doc/html/rfc9319
Specifically 5.1 which indicates having dormant ROAs available for use,
but I am being told having any dormant ROAs is grounds for all routes to
be marked invalid based on stricter validators, which is the answer im
trying to ascertain right now.
In a failover sense, say for example I am advertising /22 out of my
Brisbane POP and some /24's out of my Sydney POP, my Sydney POP goes
down and im no longer originating those /24's, by what i've been told my
/22 would now become invalid on next check as my /24's are not being
advertised, even though I have ROAs for the /22 and /24's.
I believe i've been given somewhat wrong information but they were
basing it off experiences with other APNIC members, I just dont want to
end up in a position where our routes are dropped after implementing our
ROAs, and maintain flexibility to not wait multiple hours before we can
advertise a new prefix if required.
Thanks,
Joe
------ Original Message ------
From: "Phil Mawson" <phil.maw...@gmail.com>
To: "Joseph Goldman" <jos...@goldman.id.au>
Cc: "ausnog@lists.ausnog.net" <ausnog@lists.ausnog.net>
Sent: 23/05/2024 3:52:54 PM
Subject: Re: [AusNOG] Experiences with RPKI
Hi Joe,
First up, well done on working on your RPKI roll out. Signing your own
routes is the most important step you can take to protect your own
network.
In regards to using max length, I do advise against that as what it
means someone can still hijack one of your un-advertised routes and it
would be treated as real.
IE: If you advertise and sign a /19, but have a ROA created for each
route up to a /24. If you are not advertising all of those, a third
party could advertise one of our /24s and spoof your ASN and it would
be treated as valid on the internet.
APNIC portal make it very easy to create ROAs for your own routes as it
has the route table view so it can see what is already publicly
advertise. I recommend looking at that and then signing routes based
on that.
DDoS mitigation providers and ROAs is an interesting topic and not
sure the community can agree on what is the best technical solution for
that.
Regards,
Phil
On 23 May 2024, at 3:46 PM, Joseph Goldman <jos...@goldman.id.au>
wrote:
G'day list,
In the process of rolling out RPKI - and while I thought I had a good
grasp on everything, there is one niggling piece of information that
I've come against and can't verify. Was hoping people can share their
experiences.
We are only doing our ROA's to begin with and not implementing
validation until later, the initial thought was to create an ROA for
all our 'supernets' and use maxLength to 24 to help cover any prefix
we may want to advertise. We are a much simpler setup, single AS only
and we do advertise many of our ranges down to /24 but not all of
them. I do know of the best practices of not using maxLength based on
a draft rfc doc, but I am personally not super concerned for our
relatively small use-case to the issues brought up in that doc.
Where I have come into trouble is a source (APNIC helpdesk)
indicating that if we have any ROAs that exist for prefixes we are not
directly advertising - it may lend some validators to mark all our
routes as invalid?
i.e. say we had /22 ROA, 2x /23 ROAs and 4x /24 ROAs - are currently
advertising the /22 and 2x /24's, so 2x /23's and 2x /24 ROAs are
'unused' in that we are not advertising those specific resources -
would that cause issues with strict validators out in the wild?
My understanding reading through the RFC's is this should not be the
case. If any ROA that matches the prefix for the origin AS exists it
should be valid, regardless of other ROAs signed by the same resource
holder etc.
Matching ROAs to exact advertisements is great, but it seems to lend
itself to much less flexibility in traffic engineering and failover
scenarios - a good scenario is having dormant /24 ROAs for say a DDoS
mitigation service to use when needed, so you dont have to wait for
RPKI propagation before scrubbing kicks in.
Based on your experience, is having all-encompassing (using
maxLength), or unused ROAs an acceptable way to use RPKI or will we
run into issues?
All help appreciated :)
Thanks,
Joe
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