Postfix-Server behind a DSL-Router

Thu Apr 9 19:54:53 UTC 2015

Am 09.04.2015 um 20:52 schrieb Andy Blanchard:
> Hi Peter,
>
> 0.0.0.0 is a "wildcard"; Postfix is definitely running and listening
> for incoming connections on port 25 on any IP address on your server.
>
> Do you have access to another PC or something on your internal network
> that you can try connecting from?  At least that way you could
> determine whether you need to focus on the router or the server -
> although based on your updates on FirewallD and Postfix, I'm leaning
> more towards either the router or your ISP blocking SMTP by default at
> present.
Hi Andy,

I have some old laptop running debian. Can I do something with it - 
without setting up another mail server on it?  :-)

>
> On the latter point, it might be worth looking at their FAQ or maybe
> contacting support just in case; some ISPs block SMTP by default as an
> anti-spam measure but will open it up on request, but others require
> you have some form of "premium" connection to host your own servers.
>
> Andy
>
> On 9 April 2015 at 19:16, Peter Ulrich Kruppa <pukruppa at googlemail.com> wrote:
>> Am 09.04.2015 um 19:05 schrieb Rick Stevens:
>>>
>>> On 04/09/2015 07:22 AM, Peter Ulrich Kruppa wrote:
>>>>
>>>> Am 09.04.2015 um 15:32 schrieb Robert Nichols:
>>>>>
>>>>> On 04/09/2015 05:07 AM, Peter Ulrich Kruppa wrote:
>>>>>>
>>>>>>
>>>>>> I set up a Postfix-Server on my Fedora 21 box, which is connected to
>>>>>> the internet via
>>>>>> some Netgear Router. My private LAN is 192.168.10.0/24 with the Fedora
>>>>>> box fixed on
>>>>>> 192.168.10.1 . My Netgear thing has got a fixed IP and hostname, let's
>>>>>> say for
>>>>>> mydomain.com .
>>>>>>
>>>>>> Now I can
>>>>>>     - send myself mails from my Fedora box
>>>>>>     - send mails from my Fedora box to the outside p. ex. my googlemail
>>>>>> account
>>>>>>
>>>>>> but I can't receive mails from outside.
>>>>>
>>>>>
>>>>> The default postfix configuration has it listening only on the localhost
>>>>> interface.  You will have to change that.  Look for "inet_interfaces ="
>>>>> in /etc/postfix/main.cf .
>>>>
>>>> I have got
>>>>       inet_interfaces = all
>>>> in there.
>>>
>>>
>>> Many ISPs block SMTP traffic TO their end users. Most also block
>>> outgoing SMTP traffic FROM their end users _unless_ it's going to the
>>> ISP's mail servers (this is to prevent end users from becoming spam
>>> farms). Assuming your ISP permits bi-directional SMTP traffic, here
>>> are things to look at:
>>
>> It does - I had that working using a DSL bridge (modem) instead of a router.
>>
>>> 1. The outside world must send mail to the PUBLIC IP of your firewall
>>> (not the 192.168.x.y address, but the one that's on the public
>>> Internet). Make sure your MX DNS records reflect that public IP address.
>>> If your MX records contain "192.168.x.y" or "10.x.y.z", then your record
>>> is wrong (192.168.0.0/16 and 10.0.0.0/8 are non-routable, private
>>> networks).
>>>
>>> 2. You must configure your external firewall to forward incoming port
>>> 25 traffic to port 25 on your postfix machine's PRIVATE IP address.
>>>
>>> 3. Make sure firewalld on your postfix machine permits incoming port 25
>>> traffic.
>>
>> Points 1. to 3. should be allright - hopefully ...
>>
>>> 4. You must make sure postfix is listening on the private IP address (at
>>> least). "netstat -lpnt | grep 25" will tell you what IPs postfix is
>>> listening on.
>>
>>          # netstat -lpnt | grep 25
>> tcp        0      0 0.0.0.0:25           0.0.0.0:*
>>                                   LISTEN      1494/master
>>
>> How do I read/understand that output? Shouldn't there be 192.168.10.1:25 ?
>> (By the way: I didn't know postfix daemon is called "master" ,,,)
>>
>>
>> Greetings
>>
>> Peter
>>
>>
>>> ----------------------------------------------------------------------
>>> - Rick Stevens, Systems Engineer, AllDigital    ricks at alldigital.com -
>>> - AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
>>> -                                                                    -
>>> -   Errors have occurred. We won't tell you where or why.  We have   -
>>> -                         lazy programmers.                          -
>>> ----------------------------------------------------------------------
>>
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>
>
>