Mailinglist Archive: opensuse (4633 mails)

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Re: [opensuse] Open (subnet) Relay using Postfix
  • From: "Joe Morris (NTM)" <Joe_Morris@xxxxxxx>
  • Date: Fri, 29 Dec 2006 19:19:24 +0800
  • Message-id: <4594F9BC.8060802@xxxxxxx>
John Andersen wrote:
> I've discovered that the default Postfix install as done in openSUSE 10.2
> and SLES9 provides an open relay for anyone on the same subnets
> as the mail server.
That is basically stated in Yast2, System, etc/Sysconfig Editor, where
it says
File: /etc/sysconfig/postfix
Possible Values: subnet, host, class
Default Value: subnet
Configuration Script: postfix

The postfix default for this setting is "subnet"
for security reasons you should use host
otherwise every user in the same subnet as you, can use
your postfix server as a mail relay for spam.
If you set POSTFIX_DIALUP to "yes" mynetworks_style
will be set to "host" by SuSEconfig.

Mine was set to host, but I no longer remember if I did that or
Yast/SuSEconfig did it.
> By adding the line:
> mynetworks =,
> you can prevent this, but Yast does not offer that as
> best I can see, so you have to remember to do it
> manually.
You do need to add it manually, but you could add POSTFIX_ADD_MYNETWORKS
to /etc/sysconfig/postfix to edit this easily with Yast's sysconfig editor.

Joe Morris
Registered Linux user 231871 running openSUSE 10.2 x86_64

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