Postfix-Server behind a DSL-Router

[Peter Ulrich Kruppa]

Am 09.04.2015 um 12:07 schrieb Peter Ulrich Kruppa:
> Hi everyone,
>
> please do excuse my unspecific subject - I don't really know what my
> problem is yet.
>
> 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.
>
> When I do a
>      # tcpdump -n -i any tcp port 25
> on my Fedora I can see many messsages like
>
> 10:34:09.338691 IP 212.227.17.11.64945 > 192.168.10.1.smtp: Flags [S],
> seq 3273717964, win 14600, options [mss 1418,sackOK,TS val 1273019143
> ecr 0,nop,wscale 9], length 0
> 10:34:10.339378 IP 212.227.17.11.64945 > 192.168.10.1.smtp: Flags [S],
> seq 3273717964, win 14600, options [mss 1418,sackOK,TS val 1273019393
> ecr 0,nop,wscale 9], length 0
> [...]
>
> Any good ideas, what else I can do to analyze my problem?
>
> Thanks for your answers
>
> Peter
> .
>
Now let's test something bad and completely turn of my firewalld !