Hi Sean, hi Gorry, Thanks for your review and feedback. Please see below. > On 13. Aug 2019, at 09:56, Gorry Fairhurst <gorry@xxxxxxxxxxxxxx> wrote: > > See below: > > On 13/08/2019, 02:08, Sean Turner via Datatracker wrote: >> Reviewer: Sean Turner >> Review result: Has Nits >> >> Hi! I'm no congestion control expert so nothing in the main body jumped out at >> me. I did take a little time to review some security considerations for other >> congestion control RFCs and just wanted to make sure the same kind of >> information is getting addressed. I indicated the result of this review as >> "has nits" because there is a pretty good chance I am just suggesting some >> editorial tweaks. >> >> The security considerations rightly points out that this mechanism is >> susceptible to the same kind of attacks as TCP (e.g., hijack, replacement) and >> what mitigations to use (i.e., integrity protection of the RTCP feedback >> messages). But, what is missing is what happens if these attacks succeed: DoS >> or in the worst case congestion collapse? So, maybe instead of: >> >> As such, it is vulnerable to attacks where feedback >> messages are hijacked, replaces, or intentionally injected with >> misleading information, similar to those that can affect TCP. >> >> Maybe: >> >> As such, it is vulnerable to attacks where feedback >> messages are hijacked, replaces, or intentionally injected with >> misleading information resulting in denial of service, similar >> to those that can affect TCP. >> >> Also, unless I've completely misread this paragraph it seems like you are >> talking about two things: 1) it's just like TCP, and 2) "The modification of >> sending rate ...". So, maybe split the paragraph along those lines. I think this is actually based on text that we used for scream (now RFC8298) which is another congestion control developed in rmcat. I think we refined that text also based on a SEC (or GEN?) review comment at that time and people were at the end satisfied with it. However, your proposed change above could surely be integrated and I leave it to the authors if they want to refine the text further. >> >> Further questions: >> >> 1. Are there any concerns related to a greedy receiver who wants to gobble up >> more than its fair share of network bandwidth? This is a very general point for all congestion control schemes, and for rmcat it is also discussed in draft-ietf-rmcat-cc-requirements (which is sitting in the RFC editor queue for a while as part of the 238 cluster…). I personally don’t see too much value in discussing this here once again (given the generic nature of the problem and very unclear definition of “fair”). >> >> 2. Seems like maybe you also need to refer to the RTP/RTCP security >> considerations because it seems like security primarily needs to be considered >> in the context of a specific transport protocol and its authentication >> mechanisms. Hm, also not sure here because, while this congestion control scheme is developed for RTP/RTCP, it's defined in a more generic way and there are actually no real dependencies on a specific protocol. >> >> Cheers, >> >> spt > I also think that text (or similar) would also be valuable in the security considerations section. > Gorry: Can you further explain what part this comment related to? Thanks! Mirja > Gorry >
