Re: Network tcp/iptables issue with XRDP

[Arno Lehmann <al@its-lehmann.de>]

Hi Henggi, all,

Am 24.10.2023 um 14:04 schrieb Henggi:
> Hi list,
>
> Completely stuck here, any clue appreciated!
>
> Trying to bring up XRDP service on Debian 11-bullsyeye (arm64, incl. backports, fully up-to-date) which is only listening on „lo“ interface (not eth0) even netstat indicates otherwise:
> -> incoming tcp syn/ack on localhost interfact (lo) works fine
> -> incoming tcp syn/ack on eth0 interface seems not to reach app listening process (while other services on same host are working just fine via the network - so it’s not an „physical" network issue).
> -> iptables are cleared and not aware of any other netfilter running…

I suggest to verify the other netfiler options.

Recently I encountered something similar, and my usual test for local 
firewall being active,

iptables -L -n

came back with policies "accept" all over the place, and no particular 
rules.

Took me a while to understand that firewalld can still do its job.

So, probably useful to check with

systemctl status firewalld

and use firewallcmd in an appropriate manner, if you find that to be active.

Good luck!

Arno

--
Arno Lehmann

IT-Service Lehmann
Sandstr. 6, 49080 Osnabrück