Re: [MBONED] Eric Rescorla's Discuss on draft-ietf-mboned-mtrace-v2-22: (with DISCUSS and COMMENT)
Eric Rescorla <ekr@rtfm.com> Mon, 09 July 2018 13:55 UTC
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From: Eric Rescorla <ekr@rtfm.com>
Date: Mon, 09 Jul 2018 06:54:54 -0700
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To: Hitoshi Asaeda <asaeda@ieee.org>
Cc: Kerry Meyer <kerry.meyer@me.com>, draft-ietf-mboned-mtrace-v2@ietf.org, The IESG <iesg@ietf.org>, MBONED WG <mboned@ietf.org>, mboned-chairs@ietf.org
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Subject: Re: [MBONED] Eric Rescorla's Discuss on draft-ietf-mboned-mtrace-v2-22: (with DISCUSS and COMMENT)
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On Mon, Jul 9, 2018 at 6:51 AM, Hitoshi Asaeda <asaeda@ieee.org> wrote: > Eric, > > > >> Section 4.2.1, however (see below), prohibits processing of a Request > that is not sent from an adjacent router. Also, it is worth considering > that this problem hypothesis supposes that a DoS attack is launched from a > trusted router address. Even for this scenario, however, the document does > provide protection. The normative descriptions to which the quote above > refers are: > > >> > > >> - The previous paragraph from section 9.2 (requirement for use of > ACLs; slightly reworded later in this email to the new proposed text): > > >> > > >> ---------- > > >> A router MUST support an access control list (ACL) mechanism to > > >> filter out Queries from clients and Requests from peer router > > >> addresses that are unauthorized or that are beyond a specified > > >> administrative boundary. This filtering could, for example, be > > >> specified via a list of allowed/disallowed client and peer addresses > > >> or subnets for the Mtrace2 protocol port. If a Query or Request is > > >> received from an unauthorized address or one beyond the specified > > >> administrative boundary, the Query/Request MUST NOT be processed. > > >> The router MAY, however, perform rate limited logging of such > events. > > >> ---------- > > >> > > >> and > > >> > > >> - Section 4.2.1 (required validity checks to force rejection of a > Request message from a source that is not an adjacent router): > > >> > > >> ---------- > > >> 4.2.1. Request Packet Verification > > >> > > >> If the Mtrace2 Request does not come from an adjacent router, or if > > >> the Request is not addressed to this router, or if the Request is > > >> addressed to a multicast group which is not a link-scoped group > > >> (i.e., 224.0.0.0/24 for IPv4, FFx2::/16 [3] for IPv6), it MUST be > > >> silently ignored. The Generalized TTL Security Mechanism (GTSM) > [14] > > >> SHOULD be used by the router to determine whether the router is > > >> adjacent or not. > > >> ---------- > > > > > > Unless I'm missing something, this just restricts things to a *node* > which is adjacent. But if I'm a device that's on the same LAN as a router > (which isn't a crazy proposition, ISTM), then why can't I mount this attack? > > > > Only an adjacent *multicast router* can send requests, because a request > is transformed from a query initiated by a downstream node/device and > forwarded toward the source/RP > > > > But the difference between a request and a response is just some bits in > the packet. > > I cannot understand this comment. > It is very common to design protocol messages using the TLV format and > differentiate the messages by the different type values. > Yes. That's why it's important to have the receiver check. > > And so what stops some other host on the LAN from sending something that > claims to be a request. > > We cannot stop someone from sending packets, but can > ignore/drop/rate-limit the packets if something wrong. > Yes. > > In your example, you are a valid *user (or device)* and send Request, > and can attack someone. But in our definition, you cannot send any Requests > because you are not a valid *multicast router*. > > > > Yes, but that needs to be technically enforced, not just stated. > > Right. That's why we propose a new type of ACLs as follows. > > > > The problem you may think here is that the ACLs in general do not > validate the Request is traversed from valid (or invalid) routers as the > message types cannot be specified in ACLs, right? > > If we define a *particular* ACL entry to specify accepted/non-accepted > IP addresses (or ranges) or admin boundaries for each of three mtrace > message types, Query/Request/Reply, will your concern be disappeared? > > > > I think so, if you require its use. > > Ok, fine. I'll explain this ACL extension in the upcoming meeting. > > > To protect against spoofing of Request packet, as Kerry said, > > > > NOTE: To protect against spoofing of Request packets by a trusted > host, some authentication mechanism such as use of an Authentication Header > (AH) between routing peers should be also considered. However, discussion > of such external authentication mechanisms is out of the scope of this > document. > > > > Also, router validation is in general defined in the routing protocol > specifications and routers can run the authentication mechanisms. We do not > provide an mtrace unique/specific authentication mechanism for routers in > this document. But as the example, we can describe the PIM case to verify > adjacent PIM neighbor routers, if it's helpful. > > > > I don't follow this. > > Is some point unclear for you? > Let's see PIM-SM (multicast routing protocol). PIM-SM has a way to > verify/recognize a valid PIM neighbor. If you need such adjacent router > verification, we can mention this routing protocol's verification > mechanism. > > > > Given that we're a week from Montreal, it might be easier to just try > to meet there. What say you? > > > > Although Kerry may not, I'll be there. > > I asked a slot to report the current situation in the Mboned WG meeting. > Please come to the meeting. > > > > I have to be at RTCWEB. > > Hmm.. Then we won't be able to reach any consensus in the meeting... > > > But before the f2f discussions or the meeting, I need to understand and > clarify problems you have been thinking. > > > > The point of the F2F discussion is to clarify the issue. > > I'll then personally contact you to meet next week. > That's fine, but if you send me proposed new text beforehand, I can also review it. > > Regards, > > Hitoshi > > > > > -Ekr > > > > > > Regards, > > > > Hitoshi > > > > (snip a lot) > >
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Kerry Meyer
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Kerry Meyer
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Warren Kumari
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda
- [MBONED] Eric Rescorla's Discuss on draft-ietf-mb… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Toerless Eckert
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Toerless Eckert
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Toerless Eckert
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Toerless Eckert
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Warren Kumari
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Warren Kumari
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Kerry Meyer
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Kerry Meyer
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Kerry Meyer
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Eric Rescorla
- Re: [MBONED] Eric Rescorla's Discuss on draft-iet… Hitoshi Asaeda