mouss writes: > Ralf Hildebrandt wrote: > > * mouss <[EMAIL PROTECTED]>: > > > >> I respect you, but I feel sorry here. Tarpit and slowdown are know since > >> a long time, so mailchannel bring nothing here (except marketing). In > >> particular,"greet pause" has been implemented by some people. the fact > >> that this is not common is not due to an implementation difficulty, but > >> to the fact that the cost/benefit ratio is not very interesting. > > > > To be fair (I'm testing it right now): It's easy to get running. > > Right now the Tarpit and slowdown features cannot be had in Postfix, > > so I'm giving it a spin. > > you can use sleep. sure, it stops the process, but if your system is not > under heavy load, it may be acceptable... > > but anyway. I don't see what mailchannel are bringing that deserves this > debate. it looks to me like this: > > - they started trying to sell greeetpause. and it didn't work enough > - they moved to "slowdown" and they're trying to talk about
For what it's worth, they've been talking about "slowdown" since 2006: http://www.onlamp.com/pub/a/onlamp/2006/10/12/asynchronous_events.html > In both cases, they don't provide any serious study. they only show > numbers that go with their claims. I don't know for others, but my logs > don't seem to confirm theirs. OK, the main advantage over doing greet-pause/tarpitting with your "main" SMTP daemon is that TC is event-driven; thousands of concurrent connections are handled by one TC process. So it'll scale better -- I don't know of an MTA that can do that on low-end hardware (bar a custom, hand-tweaked qpsmtpd setup, and I've been having trouble doing that myself for our spamtraps). It also can cluster between multiple instances (apparently) if that's not scaling enough. > and the slowdown thing is based on the theory that spammers have better > things to do than wait. now that we know more about botnets, this theory > doesn't stand. > > how long would it take to write an asynchronous smtp client? You think spammers aren't already using them? too late I'm afraid; I know that one of the major ratwares is already written using libevent: http://www.monkey.org/~provos/libevent/ . And I'm sure there are more. Installing something like Traffic Control is simply keeping up. The spammers can already scale better than we can. We're spared the full flood, because they're simultaneously relaying spam to thousands of other servers while they're flooding ours... but they'll keep scaling up. --j.
