Hello,
I have been researching this subject and was wondering if somebody had
suggestions....
We are using Exim as an MTA from Linux to Domino (on a W2K3 server) server
and I would like to filter incoming mail before it is routed to the Domino
server. Unfortunately, we are getting a lot of dictionary attacks on our
server and the mail is relayed to our Domino server because the attacks
have the right domain (but not the right local users). Essentially, before
the mail is routed to Domino, I want to do a lookup from a text file
containing a list of company users and if the incoming message is destined
to a user NOT on the list, then I would like to stop it outright, not have
it bounce back or anything. A method was suggested to me but I wasnt sure
where to put it in my config file. Here is what was suggested by Tabor J.
Wells (I plucked out the relevant part)...
"...You have several options here. The simplest one is to compile a list
of
all valid email addresses (just the part before the @) in your
organization and put it on the Exim server and reference it in the acl
for your rcpt checking. This is off the top of my head so make sure you
make a test copy of your exim config and use the -C option to test it
before you make it live. Testing with -bh and -bt in conjunction with -C
will allow you to make sure you haven't broken anything important
before you put the new config live.
So you'd have something like the following as the end of your rcpt acl:
accept local_parts = lsearch;/path/to/your/valid/addresses.txt
domains = yourdomain.com : yourotherdomain.net
deny message = no valid recipients found "
I saw question 9802 and was wondering if there was something that could be
done in reverse... The solution from Mr. Wells seems ok but as mentioned,
I am not sure where to put it in the Config file. I also wonder if there
are any special rules that I will have to use when creating the text file
(such as delimiters for the names, etc...) that will be used for the
lookup.
Raymond Monette
