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List:       mythtv-users
Subject:    Re: [mythtv-users] Backend connections fail - stumped
From:       jam <jam () tigger ! ws>
Date:       2023-11-14 4:16:04
Message-ID: 02712092-30A0-4F2F-95BE-42151445513E () tigger ! ws
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> On 14 Nov 2023, at 11:44 am, Stephen Worthington <stephen_agent@jsw.gen.nz> wrote:
> 
> On Mon, 13 Nov 2023 16:01:17 -0600, you wrote:
> 
>> My long running backend daemon has recently stopped accepting connections
>> on port 6543.  Even simply invoking "mythbackend --printsched" gets the
>> cold shoulder.  I've tried invoking the daemon with "-v all" and
>> "--loglevel debug", but either I'm looking in the wrong log(s) or nothing
>> is logged during these connection attempts.
>> 
>> In short, the backend logs don't show anything at all when mythbackend,
>> mythwelcome, and/or mythfrontend try to connect and the connecting
>> applications' logs simply report that the connection, both by lan IP
>> (192.168.x.x:6543) and local IP (127.0.0.1:6543) fail with messages like:
>> 
>> 2023-11-13 14:21:17.436230 I  MythCoreContext: Connecting to backend
>> server: 192.168.x.x:6543 (try 1 of 5)
>> 2023-11-13 14:21:17.436780 E  MythSocket(abde80:-1): Failed to connect to (
>> 127.0.0.1:6543) Connection refused
>> 2023-11-13 14:22:17.523316 I  MythCoreContext: Connecting to backend
>> server: 192.168.x.x:6543 (try 2 of 5)
>> 2023-11-13 14:22:17.523815 E  MythSocket(abde80:-1): Failed to connect to (
>> 127.0.0.1:6543) Connection refused
> 
>> I would greatly appreciate any help in figuring this out.
> 
> I presume that this is a frontend trying to connect to a separate
> backend box.
> 
> The localhost connection attempt will always fail because there is no
> mythbackend running on the frontend box.
> 
> The mythbackend log not showing any connection attempts suggests that
> the traffic from the frontend box is not getting to mythbackend at
> all.  The frontend logs saying "Connection refused" suggests that port
> 6543 on the backend box is closed, but that the backend box is sending
> a NAK packet when it receives a SYN packet to start a TCP connection
> on that port - it is saying that the port is closed, rather than just
> ignoring the SYN packet.
> 
> Does the backend box have a screen?  Does mythfrontend work there?  Is
> port 6543 open on the backend box's IP address?  Try running this on
> the backend box:
> 
> sudo netstat -anp | grep 6543
> 
> Do you see a LISTEN line with 0.0.0.0, ::, or the specific IP address
> of the box?  If not, then you need to fix the mythbackend settings so
> that it is listening for external connections.
> 
> From the frontend box, try manually connecting to the backend:
> 
> telnet <backend IP> 6543
> 
> This is the sort of thing you should see if it does connect:
> 
> root@crw-pvr:~# telnet mypvr.4.jsw.gen.nz 6543
> Trying 10.0.2.4...
> Connected to mypvr.4.jsw.gen.nz.
> Escape character is '^]'.
> ^]
> telnet> quit
> Connection closed.
> 
> If it does not connect, but there is a LISTEN port open in the netstat
> output, then there is likely a firewall on the backend machine (or
> possibly the frontend machine) that is stopping the traffic, or there
> is a routing problem in your network.  Are you able to ping the
> backend box from the frontend box?

Steven gives you nice step-1's
How about step-0
On backend machine is backend running ?

$ ps -ef |grep myth

How do you start the backend? eg for systemd

$ systemctl status mythbackend

What is the last thing logged? in normal backend logs.

James
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