Third Party Relay

[possimboy]

Hello,

I'm using 8.12.10 of Sendmail on a box that receives all the mail passes it through our spam filter then shoots it out to two other mail servers one for domain.ca and the other for sub.domain.ca

The problem I'm having is that it is open for hijacking when someone uses one of my addresses as the sender. I can recreate this in relay testing putting in the same address for the sender, recipient and from. on this test

http://members.iinet.net.au/~remmie/relay/

not sure how to close this hole or block the other servers without cutting all my mail off.


Can someone help?

Let me know what files your wanna see and I'll post them.

Thanks

 

[Rhinokiller]

Check how your access file is set up. You should be relaying for localhost and/or the IP of your mail system only. Your domain name should also be included here.
localhost RELAY
127.0.0.1 RELAY
yourdomain.ca RELAY
123.45.67.89 RELAY (dotted decimal address of email "source" - either the dmz lan interface or local lan if no dmz).
You should not be relaying mail for anyone else in this file.
Now check your relay-domains file and add ONLY your domain and sub domains.
Now add your domains to the local-host-names file (re. sendmail.cw)
This should close all open relays.

Cogito Ergo Sum - Non Compos Mentis

 

[possimboy]

Thanks.

I closed those holes which I came to realize were closed to begin with but in a different way. I was pounding my head against the wall because my boss and another higher up were sure it was a hole. But what I was actually trying to close was my mail servers ability to receive a proper ( sort of) email.


The message was a message to a user, from the user from another mail server. A rule check I think I need to put into a mimedefang filter.

If someone knows the rule script for that I would appreciate that and save me a bit of time.

Thanks.

Now I must go and heal the bruises on my head.

 

[Rhinokiller]

The message was a message to a user, from the user from another mail server

As long as you are not relaying mail for that other domain I don't see the problem.

Cogito Ergo Sum - Non Compos Mentis