[mythtv-users] HDHOMERUN on different network

[Stephen Worthington]

On Sun, 5 Mar 2023 13:29:55 -0600, you wrote:

>I have two properties in different geo's with an IPSEC tunnel between 
>them.  I want to setup an HDHOMERUN in location B and have the backend 
>at location A use it.
>
>Location A is 192.168.0.x addressed. Location B is 10.0.0.x addressed.
>
>Auto discovery of the HDHOMERUN in location B by mythtv does not work.  
>Where can I enter the IP address of the HDHR in location B?  Nothing is 
>available in the GUI.
>
>I looked at the captuercard table in mythconverg database, but did not 
>see an option for an IP address.  I only see the "videodevice" column 
>with the serial number of the HDHR's at location A.
>
>
>+----------------------+ +--------------------+
>| Location A           |                   | Location B |
>| MythBackend          |                   | HDHR Tuner 3 |
>| HDHR Tuner 1,2       |    IPSEC          | 10.0.0.0/24 |
>| 192.168.0.0/24       +-------------------+ |
>|                      |                   | |
>|                      |                   | |
>|                      |                   | |
>+----------------------+ +--------------------+
>
>
>Thank you

For autodiscovery to work, mythbackend needs to be on the same subnet
as the HDHR tuner.  You can do that by using a layer 2 VNP connection
instead of IPSEC (layer 3).  With a layer 2 connection, all the
broadcast packets will be sent between the two connected subnets, and
the remote subnet will be able to use the local DHCP server to assign
its IP address from the same range as the local subnet.  The remote
subnet will also see the local IPv6 RA packets and will pick up IPv6
addresses from that using the local subnet settings.  The downside of
using a layer 2 VPN is the same as the upside - all the broadcast
traffic goes over the VPN connection and uses bandwidth that might
otherwise be available for the more useful traffic.

Most VPNs only do layer 3 (eg IPSEC, Wireguard), but OpenVPN also
supports layer 2 using a bridged tap interface instead of a routed tun
interface.  That is what I use on my laptop when I am away on holiday,
although I have yet to have the luxury of a connection fast enough to
be able to play all recordings from the home backend directly on a
remote mythfronted - so far only SD recordings have worked.  But the
networking is just as though I was at home, except for slower
responses due to the lower speed of the VPNed connection.

OpenVPN is quite difficult to configure properly - there are a huge
number of options, and getting them wrong can make it insecure.  And
bridged networking is also more complicated to set up.  It is all
documented, but it can take quite a while to get it to work.  It is
also best run on a decent CPU (a PC) at both ends, as routers rarely
support OpenVPN being able to use their encryption hardware and their
CPUs are too slow.  If you would like to get a copy of my working
configuration to work from, please email me off list.

But it really would be better if MythTV supported direct IP addressing
for HDHRs - I thought it could do that.  It is a fairly obvious need
if you want to share your HDHRs between your normal network and your
guest WiFi, for example.