nextcloud client connects not only to where I want it

[alphafrau5]

⚠️ Before posting ⚠️

• [X] This is a bug, not a question or an enhancement.
• [X] I've searched for similar issues and didn't find a duplicate.
• [X] I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
• [X] I agree to follow Nextcloud's Code of Conduct.

Steps to reproduce

Using the client in a 'normal' way

Expected behaviour

client should connect to my nextcloud instance

Actual behaviour

client connects to other servers

Android version

12

Device brand and model

cat s52

Stock or custom OS?

Stock

Nextcloud android app version

3.23.0

Nextcloud server version

24

Using a reverse proxy?

I don't know

Android logs

No response

Server error logs

No response

Additional information

No response

[debojyoti452]

@alphafrau5 Tried to reproduce it, but couldn't. Can you please add some brief steps to reproduce it? Would be helpful

[alphafrau5]

Doesn't do it every time I use it. But does once in a while:

The times at the left are today (12-06), 11-08 and 10-28. The latter was installation on crashed and reinstalled android. Middle was a new version of the nextcloud client. And the first one today. The red colour comes from blocking access.

[alphafrau5]

tzurl.org uses https://github.com/ical4j/tzurl for timezone conversions. But why needs a 'file client' such thing? Hopefully the client doesn't read (and interprete) the files. And if an ordinary timestamp isn't good enough then why not let the server decide which version is newer? Just wondering.

[alphafrau5]

Btw the screenshot comes from https://github.com/M66B/NetGuard I use it quite a lot to block unwanted communication. A lot of apps 'phone home' or share data with eg criteo or/and google analytics and/or ...

[alphafrau5]

It goes on. I can't see a clear time sceme.

[alphafrau5]

[AlvaroBrey]

@alphafrau5 have you enabled automatic calendar backup?

[alphafrau5]

Yes.

[alphafrau5]

I now deactivated backup and see if the calls to tzurl will continue

[AlvaroBrey]

Calendar backup uses ical4j, so I guessed the calls came from there, although I'm not sure why, and that should only run once a day. I'm also not sure were they're coming from now.

[alphafrau5]

This seems to be fact: calendar backup needs the internet. The other connections will remain mysterious.

[joshtrichards]

• 217-160-0-212.elastic-ssl.ui-r.com is an IONOS host [known to host Nextcloud instances - your provider?]
• 85.214.54.211 is cunrady.de [and appears to be a Nextcloud instance - yours? :smile:]
• 2a02:26f0:e200/48 belongs to Akamai and looks to be associated with their EU presence
• s1006.shost.cloud is a hosting company in DE. Hard to say what it's associated with specifically since there are 100+ domains connected to it - e.g. https://dnslytics.com/ip/62.113.196.13

[j-lakeman]

I can reproduce this behavior with Rethink DNS. In my case Nextcloud tries to connect to 52.65.185.217, which Rethink DNS tells me is tzurl.org and apparently an Australian IP. It gets blocked as it tries to establish an unsafe HTTP connection. Just like OP pointed out, I'd expect the app only to connect to my server.

Any update on this so far?

[joshtrichards]

tzurl.org is used by ical4j (which, in turn, is used in the Calendar backup/imports feature). The outgoing periodic checks are to check for and/or retrieve updated timezone definitions in case the built-in one is out-of-date.

[j-lakeman]

Cheers got it. Is this really necessary though and if yes could the requests be made through TLS?