[ILUG] postfix whitelist smtp servers

[Ciaran Johnston]

Gavin McCullagh wrote:
> Hi,
>
> I'm looking to whitelist a few smtp servers which ours should accept mail
> from while blocking all others.  We're using postfix.
>
> The first way I thought of was to use:
>
>   smtpd_recipient_restrictions = ..., check_client_access
> hash:/etc/postfix/access, ...
>
> and then create the map with something like:
>
>   w.x.y.z OK
>   a.b.c.d OK
>   ???     401 try again later
>
> except that the ??? is the problem.  I can't figure out how to specify all
> networks.  A /8 is easy with eg. "127. " but to ban everyone would require
> 254 of those lines which can't be right.

I haven't tried it, but from access(5):

NOTE  3:  use the cidr lookup table type to specify network/netmask
patterns.  See  cidr_table(5)  for details.

And from cidr_table(5):

 The general form of a Postfix CIDR table is:

       network_address/network_mask     result
              When a search string matches the specified network block,
use the  corresponding  result  value.
              Specify 0.0.0.0/0 to match every IPv4 address, and ::/0 to
match every IPv6 address.


HTH,
Ciaran.