----- Original Message ----
From: Dada Mail <dada@PROTECTED>
To: Dada Mail Developers Subscriber <barry_page@PROTECTED>
Sent: Tuesday, 1 April, 2008 7:41:55 AM
Subject: [dadadev] Re: DoS attempt?


On Mar 31, 2008, at 2:40 AM, Barry Page wrote:



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> My server had been crashing due to severe disk thrashing, so I 
> physically monitored the console with top (linux system activity 
> monitor).

I've seen this happen if you have a large archive and a custom 
template (or without the custom template). The 'bot is probably some 
sort of spider and just has a field day with all the links and 
probably spiders them faster than it should.

I've found just enabling the cache works wonders - the Config.pm 
variable is,

    $SCREEN_CACHE

just set it to, "1":

    $SCREEN_CACHE = 1;

The cached pages are just much less resource intensive to serve up 
than dynamically creating them. Sometimes that makes things much 
smoother.

If that doesn't work, I usually rename the, "mail.cgi" file to 
something like, "__mail.cgi". and make a new mail.cgi file that has 
what I've attached as its contents.

The only thing you'll have to change is the, "$State" variable. It 
should just be a file that's in whatever directory you're saving your 
dada files in. So, if you've set, $FILES to:

    /home/youraccount/dada_files

Set $State in this script to:

    /home/youraccount/dada_files/counter.txt

What this script does is keep count on how many instances of the 
program are running, and if too many are, it'll give back a server 
error. If you're below the limit, it'll just look for, "__mail.cgi" 
and invoke it.

  I usually set a cronjob to delete the file set in, $State every hour 
or so, just so the counter doesn't stick and break Dada Mail (it's 
imperfect)

A bit brutal, but should stop what's happening. If you want to up the 
amount, play around with the, "$Limit" variable, inside the script.

Hope that's all clear ;)

--
Justin J.

Dada Mail -  Write Once: Distribute Everywhere Software
url: http://mojo.skazat.com





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On Mar 31, 2008, at 2:40 AM, Barry Page wrote:

>
> My server had been crashing due to severe disk thrashing, so I 
> physically monitored the console with top (linux system activity 
> monitor). I noticed that there were many threads of mail.cgi 
> starting up so I checked the http logs, and sure enough some machine 
> (85.54.129.60) was doing what appeared to be a denial of service 
> attack on me. Either that or it was trying to hack mail.cgi to use 
> it as a bot, find email addresses or whatever. Has anyone on-list 
> had similar experiences? i blocked that address at the firewall and 
> since have had no further issues.
>
> Regards,
> Barry Page
>
> [dada mail 2.10.11 behind apache]
>
>
>
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