RE: [Exim] question about ACL

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Author: Liu Shuai
Date:  
To: exim-users
Subject: RE: [Exim] question about ACL
Thank you for the response.

>> I am trying to set up exim so that it only allow SMTP connections from
>> certain IPs. Say, I
>> want to serve only smtp requests sent from 12.34.56.* and 23.45.67.*


>So you do not expect mail from the internet?


Sorry if I didn't make it clearer.

Yes, I do expect mail from the internet, but I don't want users to be able
to use the SMTP server to send e-mail if they are outside of my local
network(s), even if they have local e-mail accounts.

For example, a user can only send e-mail through the server if his request
is from IP
within 12.34.56.1 - 12.34.56.255 or 23.45.67.1 - 23.45.67.255.

I realize that I can disable connection at firewall level, but I suppose
that I can do it from Exim as well?

> I changed the accept hosts line in the following section
>
> #!!# ACL that is used after the RCPT command
> check_recipient:
> # Exim 3 had no checking on -bs messages, so for compatibility
> # we accept if the source is local SMTP (i.e. not over TCP/IP).
> # We do this by testing for an empty sending host field.
> accept hosts = :
>
> to be
> accept  hosts = 12.34.56.*
>         hosts = 23.45.67.*
>         endpass


>This is impossible. try:
>hosts = 12.34.56.0/24 : 23.45.67.0/24

What does the line above do? In particular, what the semantics of "/" here?

Thank you for your time.

LS