LibreOffice Online doesn't open - please wait circle forever -> is my workaround a solution or security flaw?

I’ve installed the latest LibreOffice Online version into a fresh Ubuntu 18.04 directly. I then configured two Apache proxies to route the traffic from the internet via the DMZ into the nextcloud/collabora server - which offers both services. As I have Let’s encrypt - I terminate SSL in the DMZ and route http.

Unfortunately it doesn’t work - “Please Wait” forever showing the circle turning nicely.

What next? I analysed the LOOLWSD-Log (I had to enable it) and discovered

wsd-24175-24177 2019-01-13 18:15:30.062096 [ prisoner_poll ] INF  Have 1 spare child after adding      [24182].| wsd/LOOLWSD.cpp:471
wsd-24175-24177 2019-01-13 18:15:30.062099 [ prisoner_poll ] TRC  Notifying NewChildrenCV| wsd/LOOLWSD.cpp:474
wsd-24175-24175 2019-01-13 18:15:30.062124 [ loolwsd ] TRC  Have 1 new children.| wsd/LOOLWSD.cpp:3172
wsd-24175-24175 2019-01-13 18:15:30.062139 [ loolwsd ] INF  WSD initialization complete: setting log-level to [warning] as configured.| wsd/LOOLWSD.cpp:3179
wsd-24175-24186 2019-01-13 18:15:46.286805 [ websrv_poll ] *RR  Requesting address is denied: 87.123.158.231| wsd/LOOLWSD.cpp:1997
wsd-24175-24186 2019-01-13 18:15:53.128984 [ websrv_poll ] WRN  WOPI host did not pass optional access_token_ttl| wsd/FileServer.cpp:610
wsd-24175-24221 2019-01-13 18:15:53.780938 [ docbroker_001 ] ERR  No acceptable WOPI hosts found matching the target host [eth.kryptonerd.de] in config.| wsd/Storage.cpp:250
wsd-kit-24222-24178 2019-01-13 18:15:53.889211 [ loolkit ] ERR  mknod(/opt/lool/child-roots/T7Shs0SPSFu3wAGW//dev/random) failed. (EPERM: Operation not permitted)| kit/Kit.cpp:2357
kit-24222-24178 2019-01-13 18:15:53.889279 [ loolkit ] ERR  mknod(/opt/lool/child-roots/T7Shs0SPSFu3wAGW//dev/urandom) failed. (EPERM: Operation not permitted)| kit/Kit.cpp:2364
kit-24182-24178 2019-01-13 18:15:54.782334 [ loolkit ] WRN  Kit connection lost without exit arriving from wsd. Setting TerminationFlag| kit/Kit.cpp:2202

With 87.123.158.231 beeing the address of the user accessing (not the public IP of the server).

As it looks, the proxy somehow preserves the caller’s IP (which it normally doen’t) I set both up according to the instructions (Collaboraoffice Apache Reverse Proxy

I’ve found a workaround which I works but which I do not trust yet:

In /etc/loolwsd/loolwsd.xml I added in the storage Section

<wopi desc="Allow/deny wopi storage. Mutually exclusive with webdav." allow="true">
...
      <host desc="Scheunentor" allow="true">.*</host>
...
</wopi>

Which opens the filter for all addresses and gets rid of the error message. Libre Office then works.

My question here: is it safe what I’m doing here? Would’t I open security wholes?

You probably should set it to the domain of your Nextcloud server instead of a wildcard. That is at least how you do it with the Docker container.

Thanks. I did so and it works.