[mythtv-users] One step forward, two steps back - Frontends not woring properly

[Vincent McIntyre]

On Fri, Apr 29, 2016 at 10:31:59PM +0100, Damian wrote:
<snip> 
> I ran one of the remote frontends from the command line to see what error
> messages I was getting while things were freezing, and I got lots of copies
> of messages like this ...
> 
> 2016-04-29 21:49:14.102196 I  MythCoreContext::ConnectCommandSocket():
> Connecting to backend server: 192.168.0.2:6543 (try 1 of 1)
> 2016-04-29 21:49:21.121452 E  MythSocket(3b91410:68): ReadStringList: Error,
> timed out after 7000 ms.
> 2016-04-29 21:49:21.121843 C  Protocol version check failure.
>             The response to MYTH_PROTO_VERSION was empty.
>             This happens when the backend is too busy to respond,
>             or has deadlocked due to bugs or hardware failure.
> 2016-04-29 21:49:21.122406 W  Backend : gingerserver currently Unreachable.
> Skipping this one.
> 2016-04-29 21:49:21.122558 I MythCoreContext::ConnectCommandSocket():
> Connecting to backend server: 192.168.0.2:6543
<snip>

and then you said
> Here's the output from that:
> 
> $ netstat -tulpn | grep 3306
> (Not all processes could be identified, non-owned process info
>  will not be shown, you would have to be root to see it all.)
> tcp6       0      0 :::3306                 :::* LISTEN      -
> 
> and with sudo ...
> 
> sudo netstat -tulpn | grep 3306
> tcp6       0      0 :::3306                 :::* LISTEN      819/mysqld
> 
> I'm guessing, from your comments regarding IP addresses, that this isn't
> right? There are no ip addresses there.
> 
> Should I post the output of ifcongig, or would that be a stupid security risk
> to post publicly?
> 

What this shows is mysql is listening on ipv6 but not ipv4.
First check your /sbin/ifconfig output. Should be safe to post it here,
it's on an unroutable network. If there is an interface with an IP
address that is not in 192.168.0.0/24, leave that out.

Is your network configured by network-manager or /etc/network/interfaces?

Other checks to try on the backend, please report pass/fail
a) ping 192.168.0.2
    is it pinging (pass) or not responding
    eg 4 bytes from 192.168.0.2 icmp_seq=1 ttl=64 time=0.021 ms

b) telnet 192.168.0.2 3306  (then type ^})
    to pass, should see something like:

    Escape character is '^]'.
    [ 5.5.49-0ubuntu0.14.04.1 9/}MIc8?nlS<o=!-[fkjmysql_native_password

    If you see this instead

    telnet: Unable to connect to remote host: Connection refused

    that's a fail. It means nothing is listening on port tcp/3306

c) repeat a) & b) from one of the frontends
   If a & b pass but c fails, could be a firewall but there are other
   possible issues.
   Please post the ip address of the machine you tested from too.

Vince