Date: Tue, 19 Dec 2006 11:37:26 -0500 From: Christopher Hilton <chris@vindaloo.com> To: freebsd-stable@FreeBSD.ORG Subject: Re: OpenBSD's spamd. Message-ID: <45881546.30400@vindaloo.com> In-Reply-To: <200612191347.kBJDlg5c058711@lurza.secnetix.de> References: <200612191347.kBJDlg5c058711@lurza.secnetix.de>
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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. 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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