Alf Schlichting wrote: > > > We had a similar problem on our mailserver and thunderbird as mail client. > Basicly, thunderbird has a certain timeout value for searches. If thunderbird > doesn't get a result for a search after <timeout> seconds, it assumes some > error and requests the search again. new search -> new fork -> more load > and so on. Other MUAs may have similar settings. Solution: > Search and set the timeout value in thunderbird's config editor > (IRC mailnews.tcptimeout, defaults to 60) >
Alf, thanks, and thumbs up. It is not so much of a fault of OpenBSD as it is on courier-imap and thunderbird. I did have to restart Thunderbird to make mailnews.tcptimeout actually use 600 seconds, which is sick otherwise. But after some 2.5 minutes it had nicely found the string in 'Entire Message', and otherwise behaved: no forking, no too high load. It is a nice DoS-combo, what courier-imap in conjunction with Thunderbird offer here, and one doesn't even need local access. Just any remote Thunderbird client will do, and we can't prevent the user from drag&drop some tens of thousands of messages into a folder. Or, even easier, reduce mailnews.tcptimeout, and we get one new process per one second. Sick. With the larger part of the blame on courier-imap, because it does not seem to honour its own limit of 4 or 5 sessions per IP: # Maximum number of connections to accept from the same IP address MAXPERIP=4 Also, Thunderbird surely needs two dials: mailnews.tcptimeout is pretty much okay with 60 seconds default, but its mistake is to consider a search-still-in-the-making as 'connection failure'. And to spawn a new one. > Use smaller inboxes > Get more iron:) > Sorry, no. We need to do better than allowing an easy DoS. The lever must not be iron or size, it needs to be predictable and always reasonable behaviour of the softwares. Thanks again, would have never found the problem on my own! Uwe ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Courier-imap mailing list [email protected] Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-imap
