[SURBL-Discuss] Re: ANNOUNCE: Mail::SpamAssassin::SpamCopURI 0.18

John Fawcett johnml at michaweb.net
Thu Jun 3 09:39:02 CEST 2004


From: "Jeff Chan" 

> As I understand it, SpamCopURI only handles "open" redirects where
> the redirected-to site is visible in the original URI.
> 
> I'm not sure why/if the yahoo redirectors came out of the list.
> Perhaps Eric Kolve can comment.
> 
> "Opaque" redirection sites, which encode or otherwise obscure the
> destination URI, such as tinyurl.com, are not currently handled
> in SpamCopURI (SA 2.63) or urirhsbl (SA 3.0), due to potential
> resource issues.  Following such redirections would incur network
> access, timeouts, etc. that would probably be unusable on a mail
> system with significant message volume.
> 

SpamCopURI can resolve both types of redirectors. This is
because (when enabled) it will go out and connect to the web
server for the spamvertized site IF that site is listed as
an open redirector. If spamcopuri gets a 3XX return code 
from the web server, this will contain the redirected to url.
(If the url is also an open redirector, then the operation is 
repeated up to 4 times to pick up nested chains of 
redirectors).

There is nothing specific to this functionality which 
would apply to yahoo and not to tinyurl. tinyurl is actually 
already included in the sample rules file.

This is my current setup:
open_redirect_list_spamcop_uri   drs.yahoo.com
open_redirect_list_spamcop_uri   rd.yahoo.com *.rd.yahoo.com
open_redirect_list_spamcop_uri   ads.msn.com g.msn.com
open_redirect_list_spamcop_uri   snipurl.com            *.snipurl.com
open_redirect_list_spamcop_uri   tinyclick.com          *.tinyclick.com
open_redirect_list_spamcop_uri   babyurl.com            *.babyurl.com
open_redirect_list_spamcop_uri   lin.kz                 *.lin.kz
open_redirect_list_spamcop_uri   *.v3.net
open_redirect_list_spamcop_uri   shorl.com              *.shorl.com
open_redirect_list_spamcop_uri   tinyurl.com            *.tinyurl.com
open_redirect_list_spamcop_uri   google.com             *.google.com
open_redirect_list_spamcop_uri   xurl.us

It would be a good idea to add any of these which are missing to 
the default configuration.

I think the confusion may be around the definition of an *open*
redirector. AFAIK, in this context "open" is meant to indicate
those sites which allow anyone to create a redirected url without any
type or registration, so that there is little chance of stopping the 
service being abused by spammers (like an open
mail relay which will allow anyone to use it without a prior
arrangement with the mail server admin).

In reality, the spamcopuri code is general and will work 
whether the url destination is in "clear" or "opaque"
or whether it was created by a registered or unregistered user
of the redirection service (which it can't possibly know).

John









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