[TriLUG] porn spam problem

[David Brain]

Hi,

We had similar problems with our wiki (it's a somewhat hacked around
with media wiki implementation) - in the end I went with a
quick'n'dirty CAPTCHA which did seem to work without requiring a bunch
of code changes in the wiki.

I basically created a 100 captcha images (rather than gen them
dynamically - which required libraries that weren't installed on the
server) and just had a mapping (e.g. 01.jpg = 'FXCCSFA' ) on the
server side, and just picked which image to serve randomly.  It's not
as secure as it looks to the user (-: as there are only 100 possible
answers, but it did stop the spam.

Below is the script used to gen captchas (was run on a Mac so the
-font param would need changing, uses imagemagick).

David.

===

#!/usr/bin/python
import os
import random
command="""convert -size 142x42 xc:white -font
/Library/Fonts/Baskerville.dfont  -pointsize 28  -tile
pattern:checkerboard -annotate +10+30 %s -blur 0x1 -wave 1x3 -draw
"line %s" -draw "line %s" %s.jpg
"""

def getString():
	letters='ABCDEFGHJKPRSTWXYZ'
	
	ret=""
	for n in range(6):
		ret+=letters[random.randint(0,len(letters)-1)]
	
	return ret

def getLinePoints():
	xpos=str(random.randint(0,71))
	ypos=str(random.randint(0,21))

        xpos2=str(random.randint(71,142))
        ypos2=str(random.randint(21,41))

	return "%s,%s,%s,%s" % (xpos,ypos,xpos2,ypos2)
	

fp=open('mapping.txt','w')
for n in range(100):
	
	rndString=getString()
	os.system(command % (rndString,getLinePoints(),getLinePoints(),str(n)))
	fp.write(str(n)+','+rndString+'\n')

fp.close()



On Nov 28, 2007 9:22 AM,  <dhardison at grapeape.org> wrote:
>
> > WA Brown wrote:
> >> I have a server and website. I am having a problem with robots trying to
> >> access the message board to load porn spam. Looks like captcha dont
> >> work. I
> >> get, on the average, 50 tries a
> >> day. It fills up my email and I have to delete all the entries.
> >> What can I do to stop this?
> >>
> >>
> >> WA Brown
> >> www.havenstead.net
> >>
> >>
> >>
> > what message board software ?
> > --
> > TriLUG mailing list        : http://www.trilug.org/mailman/listinfo/trilug
> > TriLUG Organizational FAQ  : http://trilug.org/faq/
> > TriLUG Member Services FAQ : http://members.trilug.org/services_faq/
> >
>
> Is porn ever really a *problem* ?   ;-)
>
> ha!
>
> --
> TriLUG mailing list        : http://www.trilug.org/mailman/listinfo/trilug
> TriLUG Organizational FAQ  : http://trilug.org/faq/
> TriLUG Member Services FAQ : http://members.trilug.org/services_faq/
>