spork at bway.net
Tue Dec 19 11:56:08 PST 2006
On Tue, 19 Dec 2006, Christopher Hilton wrote:
> Oliver Fromme wrote:
>> Dimitry Andric wrote:
>> > Oliver Fromme wrote:
>> > > What does stuttering mean? Is it similar to sendmail's
>> > > "greet_pause" feature?
>> > > See here:
>> > http://www.ualberta.ca/~beck/nycbug06/spamd/mgp00014.html
>> OK, so the answer to my question seems to be "yes". :-)
> Actually I'd say it's similar. If you telnet to port 25 on a server that's
> using sendmail's greet_pause option I'm assuming that you get nothing for 5
> seconds. OpenSD's Spamd sends the initial greeting at a rate of one character
> per second and only accepts data from you at the same rate.
It also sets the window size to something like 1 byte. :)
Someone had mentioned that this would consume many threads/processes, but
that is not the case. Bob explained that spamd runs in a select() loop.
I don't totally understand that, but to me it sounds like the same
methodology that thttpd used, and that sure scaled up nice.
Here's what I think is the latest version of Bob's talk. It's quite good.
There's audio available here:
Was the original question "when will the FreeBSD port be updated"?? :)
> Through experimentation Bob Beck determined that many spammers were dropping
> the connection and forgetting about delivering the mail completely after
> short and shorter intervals if the connection was rate limited to 1 character
> / sec. When the spammers got down to 3 seconds he modified spamd to stutter
> for 10 seconds on any connection. That feature came in on OpenBSD 3.8
> -- Chris
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