Quote from: casascius on April 05, 2013, 05:15:10 AM

Quote from: MPOE-PR on April 04, 2013, 03:07:50 PM

Quote from: deeplink on April 04, 2013, 02:50:24 PM

The point is that when merely using UDP, unlike TCP, the source can block ALL incoming traffic which makes it immune to DDoS. As casascius points out, UDP is like a radio broadcast signal. TCP is like the postal service with delivery confirmation.

At what level do you propose blocking the incoming traffic?

Before it comes within miles of the host sending it. After not informing the public who the UDP is coming from.

The UDP sending address doesn't have to be public knowledge, since not anyone can necessarily subscribe to it. It would be a private UDP feed only offered to specific known sites. The UDP feed would be used to drive the services of other sites who currently get it via websocket now, who in turn could provide that data to other downstream TCP websocket clients.

Quote from: MPOE-PR on April 04, 2013, 01:26:19 PM

Quote from: casascius on April 04, 2013, 01:11:40 PM

Also MtGox could take a position on my UDP streams idea, which could be any of the following without commitment:

a) Great idea, we haven't thought of it, and you're right, it would totally get information out immune to DDoS, we'll consider it but like anything else will take time
b) Great idea, but we don't agree it would work as well as you think it will, or for (specific technical reason) won't work on our platform
c) We haven't got a clue as to what this means
d) I don't have a clue what this means because I'm not a developer or tech guy myself, but I have relayed your suggestion to someone more technical, and he says (response). (Hopefully this suggestion is more valuable than to merely forward it blindly like the latest facebook meme, since MtGox's reputation is suffering and this will actually solve the claimed issue at hand)

Just to be clear, using UDP to broadcast ticker data would be, for all intents and purposes, IMMUNE from DDoS attacks, because such a stream consists solely of outbound traffic which is not influenced by inbound traffic. Unlike a normal stream, there is no inbound overhead for packets to acknowledge or to keep the connection in sync, packets which can be drowned out in a DDoS attack. UDP is much more like a point-to-point radio broadcast: the signal gets sent from point A to B even if nobody's listening

I don't think you understand how DDoS works on this level. Your UDP stream would have to have a source, which would have to have an IP, which then would get flooded to crap. It's the routers that pop, not the machines.

Yup as working as in ITer in a DC, if they want to hit you with DDoS a lot of tricks work, till they either flood the lines or bring down the router of the DC, where you are at. Once they hit that point, there is no stopping it. And even though the real big DC's have a dozen of 10gbit lines, at some point it just stops. (A month back we saw an DDoS we saw a DDoS peak of 250gbit hit... what do you do about it... you null the IP at your carriers. (making the site unavailable))
Though when hackers/botnets are attacking in this type of volume, there is nothing that can really save you, the only way to minimize, is host global, all with loads of overcapacity, high performance routers and heavy duty DDoS firewalls. This is the only way to truly mitigate most of them. (if they attack from US, only the US DC will get hit, and EMEA and Asia will hopefully keep running smooth, same goes for both other regions when under attack)

DDoS is one of the most difficult things to combat, purely because its nature is to flood the network, hence extra capacity would be needed to combat this. (you can't buy 100gbit of network speed when doing 1gbit of traffic just because you might get hit with a DDoS up to 100gbit... and what if they DDoS you with 101gbit?) Seeing what DDoS botnetworks have been capable of, these days you are technically not safe with anything under 2tbit.... (highest I've seen was 1.3tbit) well if your in the hosting business, you know what a 10gbit uplink costs, multiply by 200, subtract 30% a month... while it would only take a botnet of half a million with 20mbit connection to push that same DDoS out. (known botnets have been found with more then 300k bots) And then I'm not even talking about some infected webserver, on a gbit connection to the internet, that can start to DDoS as part of a botnet... (only takes a 1000 of these to get a 1tbit)

Still I think Mt.Gox can do better, DDoS can't always be completely prevent, but bot lagg time in triple digit seconds as shown earlier in the thread... that should've been impossible imo. Get that security ramped up and make sure everything is running efficient. Know you get hit by DDoS on regular basis, and apply as much pre-emptive mitigation methods as possible.