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Re: Re: Preventing DOS attack (was: severe swish-e problem (1.3.2)

From: Jose Manuel Ruiz <jmruiz(at)>
Date: Wed Jun 21 2000 - 14:11:09 GMT

David Norris wrote:
> Bill Moseley wrote:
> There are tons of things one can do to fight against DoS.  Of course,
> you normally don't think of them until something drastic has happened
> ;-)
> > I also limit two letter wildcards, and the total number of wild cards.
> Sounds like a reasonable idea.
> > The other thing I do to reduce a DOS attack is to limit the amount of time
> > for each request, and kill off swish at the timeout.

Old swish-e (1.3.2) has a terrible lack in performance when databases 
contains thousands of document and a search returns many results. For 
this reason, in phrase version I rewrote the "or" result function to 
improve speed and use less memory.

Yesterday, I also rewrote the "and" function because it has the same
problem. When "anding" two lists of results, swish-e is very slow if 
there are many occurrences in them. This is the case when wildcard is 
used in a search string.

With these changes, I think I have improved search speed notoriously.
I am testing it now in Solaris, Aix and Linux.

Other problems not fixed in the new version:
- As tested by Dave, the new beta version does not work in FreeBSD.
Yesterday I could download FreeBSD (thank you, Dave). Hope to test it 
soon. Anybody has tested it in other OS different form Solaris, Linux,
Win32 or FreeBSD?
- Bill's requirement of using wordchars while parsing search string:
Still there but not forgotten.

Have a nice day

Jose Ruiz
Received on Wed Jun 21 07:05:00 2000