Hi All
Has anyone experience of or suggestions on limiting the number of imap
sessions or rate rof connections on a per user and/or IP client address
bases.
I am planning an overhaul of our email infrastructure and would like to
include connection and rate limiting if possible.
We have occasionally had problems with email clients opening a large
number of sessions and/or bombarding the server with connections requests.
These are usually the Apple email client or ThunderBird. The number of
session was far grater then the maximum number of session to cache set in
ThunderBird. Most of the time everything is fine, however just
occasionally, possibly when the server is a little loaded, some of the
clients launch what is effectively a denial of service attach on the imap
server. It would be nice to be able to automatically throttle these
problems users/clients before they degrade the service for everyone else.
Unless I have missed something xinetd doesn’t seem have the required
granularity for this task. If I apply suitable limits fro desktop clients
it breaks the webmail service. If I set the limits suitable fro webmail
then it will do little to restrict rogue desktop clients.
ImapProxy (http://www.imapproxy.org/download.html) will be useful to
reduce the load on the server from the webmail services.
The Perdition Mail Retrieval Proxy
(http://www.vergenet.net/linux/perdition/docs.shtml) looks useful and I
will probably be using it in the new system. But again unless I have
missed something, doesn’t seem to offer any way to throttle badly behaved
clients.
Is there anything I have missed?
All the best
Richard Westlake
School of Crystallography, Birkbeck College, Malet Street, London WC1E 7HX
Tel: +44 (0)20-7631-6859
----------------------------------------------------------------------
Truth endures but spelling changes -- Anon.
----------------------------------------------------------------------
_______________________________________________
Imap-uw mailing list
Imap-uw@u.washington.edu
http://mailman2.u.washington.edu/mailman/listinfo/imap-uw
