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Need help with antivirus.exim filtering rule. How can I filter out chinese urls?

Posted on 2009-07-04
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Last Modified: 2013-11-22
I would like to set up an antivirus.exim rule to simply look at the body copy and filter the email if it contains a china based URL, i.e. a url with .cn/

I have tried several versions of the following, but it still does not work:

$message_body contains "http\:\/\/[0-9a-z]*\.?[0-9a-z]*\.?[0-9a-z]+\.cn"

also

$message_body contains "http://[0-9a-z]*\.?[0-9a-z]*\.?[0-9a-z]+\.cn"

Okay, so here is an example of the complete script in /etc/antivirus.exim
---------------------
# Exim filter
if error_message then finish endif
if
$message_body contains "http://[0-9a-z]*\.?[0-9a-z]*\.?[0-9a-z]+\.cn"
then
save "/dev/null" 660
endif
---------------------

But after restarting exim, I just try to send a simple message with a URL like the following in the body copy, and the email is allowed to pass on through.

http://www.spamalot.cn

Any help would be greatly appreciated.
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Question by:joetac
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Expert Comment

by:NerdsOfTech
ID: 24783043
$message_body contains ".cn/"
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Author Comment

by:joetac
ID: 24783330
Thanks NerdsOfTech, we considered this one, but I don't want it to be that simple. For one thing it would miss all the URLs that do not contain trailing slash. Then if we just used $message_body contains ".cn" it would inadvertantly block all the email messages that happened to contain those characters unassociated with any URL, e.g. "go to my .cnet address", etc.
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Accepted Solution

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NerdsOfTech earned 500 total points
ID: 24791138
make \. optional suffix to TLD?
$message_body contains "http://[0-9a-z]*\.?[0-9a-z]*\.?[0-9a-z\.]+cn"

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LVL 19

Expert Comment

by:NerdsOfTech
ID: 24791146
before it would match:
   www.somesite.MatchIfThisIsHere.cn
but not
   www.virus.cn
because ./ was implied as being in front of an additional prefix to TLD (suh as with .co.uk; where .co is the prefix to TLD)


The new should match (hopefully):
www.virus.cn
0
 

Author Comment

by:joetac
ID: 24791434
thanks but it still does not work, currently trying:
$message_body: contains "http://[0-9a-z]*\.?[0-9a-z]*\.?[0-9a-z\.]+cn"

I know the basic exim filtering works because other rules such as the following work fine:
$message_body: contains "phentermine"

By the way, I have also tried:
$message_body: contains "http\:\/\/[0-9a-z]*\.?[0-9a-z]*\.?[0-9a-z\.]+cn"
0
 
LVL 19

Expert Comment

by:NerdsOfTech
ID: 24792266
try:

"http\:\/\/([0-9a-z]\.)?[^/\s]+\.cn\W"
0
 
LVL 19

Expert Comment

by:NerdsOfTech
ID: 24792280
oops

try this instead:

"http\:\/\/[0-9a-z]*\.?[0-9a-z]*\.?[0-9a-z]?\.?+cn\W"
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