Re: [Bloat] Educate colleges on tcp vs udp

[Mark Andrews <marka@isc.org>]

> On 24 May 2021, at 04:47, Erik Auerswald <auerswal@unix-ag.uni-kl.de> wrote:
> 
> Hi,
> 
> On 23.05.21 12:23, Jonathan Morton wrote:
>>> On 21 May, 2021, at 9:01 am, Taraldsen Erik <erik.taraldsen@telenor.no> wrote:
>>> 
>>> I'm getting some traction with my colleges in the Mobile department on measurements to to say something about user experience.  While they are coming around to the idea, they have major gaps in tcp/udp/ip understanding.  I don't have the skill or will to try and educate them.
>>> [...]
>> I don't have a video link to hand, but let's tease out the major differences between these three protocols:
>> [...]
>> It's common to use UDP for simple request-response applications (where both the request and response are small) and where timeliness of delivery is far more important than reliability (eg. multiplayer games, voice/video calls).
> 
> As an additional point to consider when pondering whether to
> use TCP or UDP:
> 
> To mitigate that simple request-response protocols using UDP
> lend themselves to being abused for reflection and amplification
> (DDoS) attacks, either the response should be smaller than the
> request, or the protocol should require authentication, with
> either silent discard of packets that are not correctly
> authenticated, or at least a smaller error message (with rate
> limit, please) to indicate an authentication failure.
> 
> Especially if the response needs to be larger than the request,
> e.g., with DNS, a response rate limit should be applied.

DNS supports authentication of clients, be it DNS COOKIE, TSIG or
SIG(0).  If your DNS clients are not using one of these you should
contact the vendor and request a update.

> Since basic TCP first establishes a connection using small
> packets (SYN, SYN+ACK, ACK), it is less useful for reflection
> attacks than UDP.
> 
> Thanks,
> Erik
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Mark Andrews, ISC
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