Hello NANOG, To minimize the impact of DDoS, I have setup RTBH. For our own customers, we can set the RTBH community ourselves towards our transit suppliers and this works well. For our BGP customers the problem is more complex. Our BGP customers can send us the RTBH community, and we will drop the traffic at our borders. Since we're only running a small network, we don't have the capacity to deal with large attacks. If we would be able to forward (and maybe alter it) this RTBH community towards our upstream providers, the impact on our network would be limited. However, the RFC states that an announcement tagged with the blackhole community should get the no_advertise or no_export community. What is your opinion on this ? Thanks in advance Roel
On 31 Jan 2019, at 20:28, Roel Parijs <roel.parijs@gmail.com> wrote:
Hello NANOG,
To minimize the impact of DDoS, I have setup RTBH. For our own customers, we can set the RTBH community ourselves towards our transit suppliers and this works well.
For our BGP customers the problem is more complex. Our BGP customers can send us the RTBH community, and we will drop the traffic at our borders. Since we're only running a small network, we don't have the capacity to deal with large attacks. If we would be able to forward (and maybe alter it) this RTBH community towards our upstream providers, the impact on our network would be limited. However, the RFC states that an announcement tagged with the blackhole community should get the no_advertise or no_export community.
What is your opinion on this ?
Community agreed between you and your peer is one thing, the other is community agreed with your upstreams. If in addition you own the customer IP space, it’s even less of a problem. And… if you upstreams agree to signal RTBH with you, it’s added bonus for them - they’re stopping the flood at their own edges thanks to you. win-win-win-drop ;) — ./
Roel Parijs wrote on 31/01/2019 19:28:
What is your opinion on this ?
you should implement a different community for upstream blackholing. This should be stripped at your upstream links and replaced with the provider's RTBH community. Your provider will then handle export restrictions as they see fit. Nick
On 31/01/2019 20:17, Nick Hilliard wrote:
you should implement a different community for upstream blackholing. This should be stripped at your upstream links and replaced with the provider's RTBH community. Your provider will then handle export restrictions as they see fit.
This works wonderfully, from past experience. :) -- Tom
+1, exactly what we did. I also recommend implementing per-upstream/region blackhole communities (so your users can choose who to blackhole as they see fit.) Often time, DDoS traffic comes from regions that do not intersect with legitimate traffic. On 2/4/2019 03:15 午前, Tom Hill wrote:
On 31/01/2019 20:17, Nick Hilliard wrote:
you should implement a different community for upstream blackholing. This should be stripped at your upstream links and replaced with the provider's RTBH community. Your provider will then handle export restrictions as they see fit.
This works wonderfully, from past experience. :)
This is a 20+ year old solution. Ugly because you will block good traffic and on your effort to protect your network you will block legitimate traffic too (satisfying the attacker) but most upstream providers will give you a community to use (Cogent is a notable exception) and tag the prefix under attack so that the attack will not reach your network. Sadly most IXs after 20 years they still don't understand the need for this community but at least someone has written an rfc so that all of us use the same community. At least we made some progress there... -----Original Message----- From: NANOG <nanog-bounces@nanog.org> On Behalf Of Paul S. Sent: Sunday, February 3, 2019 11:08 PM To: nanog@nanog.org Subject: [EXTERNAL] Re: RTBH no_export +1, exactly what we did. I also recommend implementing per-upstream/region blackhole communities (so your users can choose who to blackhole as they see fit.) Often time, DDoS traffic comes from regions that do not intersect with legitimate traffic. On 2/4/2019 03:15 午前, Tom Hill wrote:
On 31/01/2019 20:17, Nick Hilliard wrote:
you should implement a different community for upstream blackholing. This should be stripped at your upstream links and replaced with the provider's RTBH community. Your provider will then handle export restrictions as they see fit.
This works wonderfully, from past experience. :)
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Cogent does let you use RTBH, but on a separate BGP session to a blackhole server. So it's a bit more hassle to set it up policy-wise, because it deviates from the standard. Same story for "former GlobalCrossing", now CenturyLink's AS3549, which is still used for LATAM and Asia. Best regards, Martijn On 2/4/19 9:39 AM, Nikos Leontsinis wrote:
This is a 20+ year old solution. Ugly because you will block good traffic and on your effort to protect your network you will block legitimate traffic too (satisfying the attacker) but most upstream providers will give you a community to use (Cogent is a notable exception) and tag the prefix under attack so that the attack will not reach your network. Sadly most IXs after 20 years they still don't understand the need for this community but at least someone has written an rfc so that all of us use the same community. At least we made some progress there...
-----Original Message----- From: NANOG <nanog-bounces@nanog.org> On Behalf Of Paul S. Sent: Sunday, February 3, 2019 11:08 PM To: nanog@nanog.org Subject: [EXTERNAL] Re: RTBH no_export
+1, exactly what we did. I also recommend implementing per-upstream/region blackhole communities (so your users can choose who to blackhole as they see fit.)
Often time, DDoS traffic comes from regions that do not intersect with legitimate traffic.
On 2/4/2019 03:15 午前, Tom Hill wrote:
On 31/01/2019 20:17, Nick Hilliard wrote:
you should implement a different community for upstream blackholing. This should be stripped at your upstream links and replaced with the provider's RTBH community. Your provider will then handle export restrictions as they see fit. This works wonderfully, from past experience. :)
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❦ 4 février 2019 09:01 +00, i3D.net - Martijn Schmidt <martijnschmidt@i3d.net>:
Cogent does let you use RTBH, but on a separate BGP session to a blackhole server. So it's a bit more hassle to set it up policy-wise, because it deviates from the standard. Same story for "former GlobalCrossing", now CenturyLink's AS3549, which is still used for LATAM and Asia.
Cogent will "soon" support a blackhole community on regular BGP sessions. I've got this information a few months ago, so maybe just ask for it to make it happen sooner. -- Use uniform input formats. - The Elements of Programming Style (Kernighan & Plauger)
I heard that before... -----Original Message----- From: Vincent Bernat <bernat@luffy.cx> Sent: Monday, February 4, 2019 9:48 AM To: i3D.net - Martijn Schmidt <martijnschmidt@i3d.net> Cc: Nikos Leontsinis <Nikos.Leontsinis@eu.equinix.com>; Paul S. <contact@winterei.se>; nanog@nanog.org Subject: Re: [EXTERNAL] Re: RTBH no_export ❦ 4 février 2019 09:01 +00, i3D.net - Martijn Schmidt <martijnschmidt@i3d.net>:
Cogent does let you use RTBH, but on a separate BGP session to a blackhole server. So it's a bit more hassle to set it up policy-wise, because it deviates from the standard. Same story for "former GlobalCrossing", now CenturyLink's AS3549, which is still used for LATAM and Asia.
Cogent will "soon" support a blackhole community on regular BGP sessions. I've got this information a few months ago, so maybe just ask for it to make it happen sooner. -- Use uniform input formats. - The Elements of Programming Style (Kernighan & Plauger) This email is from Equinix (EMEA) B.V. or one of its associated companies in the territory from where this email has been sent. This email, and any files transmitted with it, contains information which is confidential, is solely for the use of the intended recipient and may be legally privileged. If you have received this email in error, please notify the sender and delete this email immediately. Equinix (EMEA) B.V.. Registered Office: Amstelplein 1, 1096 HA Amsterdam, The Netherlands. Registered in The Netherlands No. 57577889.
On Jan 31, 2019, at 1:28 PM, Roel Parijs <roel.parijs@gmail.com> wrote:
For our BGP customers the problem is more complex. Our BGP customers can send us the RTBH community, and we will drop the traffic at our borders. Since we're only running a small network, we don't have the capacity to deal with large attacks. If we would be able to forward (and maybe alter it) this RTBH community towards our upstream providers, the impact on our network would be limited. However, the RFC states that an announcement tagged with the blackhole community should get the no_advertise or no_export community.
What is your opinion on this ?
In RFC7999 section 3.2 the first paragraph talks about what you're mentioning, NO_EXPORT and/or NO_ADVERTISE. It uses the word SHOULD. SHOULD has special meaning in RFCs, its not MUST. Its also not MAY. RFC2119 talks about the way these words should be interpreted. In the next paragraph it says that extreme caution should be used when "purposefully propagating IP prefixes tagged with the BLACKHOLE community outside the local routing domain, unless policy explicitly aims at doing just that." So if your local routing policy is to propagate those blackholes on to your upstreams (and its mutually agreed and they're configured to accept them), then it can be done. Nothing technical in the RFC stopping that. Theo
One more thing, RFC7999 has category Informational El 31/1/19 a las 16:21, Theodore Baschak escribió:
On Jan 31, 2019, at 1:28 PM, Roel Parijs <roel.parijs@gmail.com <mailto:roel.parijs@gmail.com>> wrote:
For our BGP customers the problem is more complex. Our BGP customers can send us the RTBH community, and we will drop the traffic at our borders. Since we're only running a small network, we don't have the capacity to deal with large attacks. If we would be able to forward (and maybe alter it) this RTBH community towards our upstream providers, the impact on our network would be limited. However, the RFC states that an announcement tagged with the blackhole community should get the no_advertise or no_export community.
What is your opinion on this ?
In RFC7999 section 3.2 the first paragraph talks about what you're mentioning, NO_EXPORT and/or NO_ADVERTISE. It uses the word SHOULD. SHOULD has special meaning in RFCs, its not MUST. Its also not MAY. RFC2119 talks about the way these words should be interpreted.
In the next paragraph it says that extreme caution should be used when "purposefully propagating IP prefixes tagged with the BLACKHOLE community outside the local routing domain, unless policy explicitly aims at doing just that."
So if your local routing policy is to propagate those blackholes on to your upstreams (and its mutually agreed and they're configured to accept them), then it can be done. Nothing technical in the RFC stopping that.
Theo
Alejandro Acosta wrote : One more thing, RFC7999 has category Informational
Point well taken. A good thing, IMHO. If I remember correctly, I once opposed this text; not because it was a bad idea (standardizing is sometimes a good idea) but because I found it imprecise enough that it was not achieveing any goal and blurred the definition of what is a RTBH. Michel. TSI Disclaimer: This message and any files or text attached to it are intended only for the recipients named above and contain information that may be confidential or privileged. If you are not the intended recipient, you must not forward, copy, use or otherwise disclose this communication or the information contained herein. In the event you have received this message in error, please notify the sender immediately by replying to this message, and then delete all copies of it from your system. Thank you!...
Roel Parijs wrote: To minimize the impact of DDoS, I have setup RTBH. For our own customers, we can set the RTBH community ourselves towards our transit suppliers and this works well. For our BGP customers the problem is more complex. Our BGP customers can send us the RTBH community, and we will drop the traffic at our borders. Since we're only running a small network, we don't have the capacity to deal with large attacks. If we would be able to forward (and maybe alter it) this RTBH community towards our upstream providers, the impact on our network would be limited. However, the RFC states that an announcement tagged with the blackhole community should get the no_advertise or no_export community.
I think the RFC is flexible enough; it's more about what you have agreed with your upstream(s) in terms of what they will accept as blackholes routes. Many upstreams will accept a destination-based blackhole if the prefix belongs to you, but accepting blackholes for other prefixes or accepting source-based blackholes requires a lot of trust. It's more a political issue than a technical one, as I see it. Michel. TSI Disclaimer: This message and any files or text attached to it are intended only for the recipients named above and contain information that may be confidential or privileged. If you are not the intended recipient, you must not forward, copy, use or otherwise disclose this communication or the information contained herein. In the event you have received this message in error, please notify the sender immediately by replying to this message, and then delete all copies of it from your system. Thank you!...
participants (12)
-
Alejandro Acosta -
i3D.net - Martijn Schmidt -
Michel Py -
Nick Hilliard -
Nikos Leontsinis -
Paul S. -
Randy Bush -
Roel Parijs -
Theodore Baschak -
Tom Hill -
Vincent Bernat -
Łukasz Bromirski