[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Bug Janitor Service]

https://bugs.kde.org/show_bug.cgi?id=375644

Bug Janitor Service  changed:

   What|Removed |Added

 Status|NEEDSINFO   |RESOLVED
 Resolution|NOT A BUG   |WORKSFORME

--- Comment #17 from Bug Janitor Service  ---
This bug has been in NEEDSINFO status with no change for at least
30 days. The bug is now closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

Thank you for helping us make KDE software even better for everyone!

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Bug Janitor Service]

https://bugs.kde.org/show_bug.cgi?id=375644

--- Comment #16 from Bug Janitor Service  ---
Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least
15 days. Please provide the requested information as soon as
possible and set the bug status as REPORTED. Due to regular bug
tracker maintenance, if the bug is still in NEEDSINFO status with
no change in 30 days the bug will be closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please
mark the bug as REPORTED so that the KDE team knows that the bug is
ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Keith Zubot-Gephart]

https://bugs.kde.org/show_bug.cgi?id=375644

--- Comment #15 from Keith Zubot-Gephart  ---
To be explicit: after adding a routing rule, I can then ping from the host PC
to the Android device (vice-versa was always true). However, the Android app
still does not see the PC as a valid pairing target, even after adding the
hostname or IP address via "Add devices by IP".

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Keith Zubot-Gephart]

https://bugs.kde.org/show_bug.cgi?id=375644

--- Comment #14 from Keith Zubot-Gephart  ---
I do intend on trying to bludgeon an OpenVPN and routing setup at work this
week (hopefully Monday if nothing else gets in the way) into accomplishing
this. I'm still somewhat unsure that this is entirely possible with my own
setup, however; Erik Duisters' solution including removing a masquerade rule
making all traffic appear to be coming from the VPN server doesn't apply to my
case, where each VPN client in fact gets its own IP address. That a lack of an
applicable routing rule is nonetheless stymieing me doesn't seem entirely
unlikely; however I've tried setting one from the host PC and added the
hostname in the Android app and seen no success.

(All of this would be abrogated, at least in scenarios identical in practice to
mine, by bluetooth support finally landing, which I'm *also* looking to try out
this week although I know it's far from actually ready yet.)

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Alexander Potashev]

https://bugs.kde.org/show_bug.cgi?id=375644

--- Comment #13 from Alexander Potashev  ---
Works for me on Android 9.0, KDE Connect for Android 1.12.5,
kde-connect-1.3.3-1.fc29.x86_64 on Fedora Linux.

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Bug Janitor Service]

https://bugs.kde.org/show_bug.cgi?id=375644

--- Comment #12 from Bug Janitor Service  ---
Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least
15 days. Please provide the requested information as soon as
possible and set the bug status as REPORTED. Due to regular bug
tracker maintenance, if the bug is still in NEEDSINFO status with
no change in 30 days the bug will be closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please
mark the bug as REPORTED so that the KDE team knows that the bug is
ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Erik Duisters]

https://bugs.kde.org/show_bug.cgi?id=375644

Erik Duisters  changed:

   What|Removed |Added

 Status|REPORTED|NEEDSINFO
 Resolution|--- |NOT A BUG

--- Comment #11 from Erik Duisters  ---
Is this still an issue for any of you? Basically when you add a device by
IP-address or hostname if any firewall allows the traffic and routing between
subnets is configured correctly everything should work as expected

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Erik Duisters]

https://bugs.kde.org/show_bug.cgi?id=375644

Erik Duisters  changed:

   What|Removed |Added

 CC||e.duiste...@gmail.com

--- Comment #10 from Erik Duisters  ---
Tested it just now with my own openvpn setup. I ran into the same problem
because when the phone is connected to my private vpn it gets a 10.x.x.x
ip-address. My vpn server masquerades all traffic from 10.x.x.x going to my
home lan. The pc I'm trying to pair with is not the vpn server so that sees the
UPD packet coming from the vpn server's 192.x.x.x address and tries to
establish a TCP connection to the vpn server which off course won't work. When
I remove the masquerading and add a route to my home pc to direct all 10.x.x.x
traffic to my vpn server all is well

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Alexander Potashev]

https://bugs.kde.org/show_bug.cgi?id=375644

Alexander Potashev  changed:

   What|Removed |Added

 CC||aspotas...@gmail.com

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Austin]

https://bugs.kde.org/show_bug.cgi?id=375644

Austin  changed:

   What|Removed |Added

 CC||potatom...@gmail.com

--- Comment #9 from Austin  ---
(In reply to Matthijs Tijink from comment #8)
> Sorry for the late reaction, I've been busy.
> 
> What the PC log message means: the PC received the UDP packet from the phone
> and tries to connect to the phone (using TCP). That fails (maybe because of
> the thing I mentioned, maybe not), so it tries the reverse: it sends out an
> UDP message so the phone will instead connect to the PC. As your issue
> indicates, that doesn't work either.
> 
> Since the android log does not contain a message that it received an UDP
> package, the direction UDP/TCP from PC to phone does not work.
> 
> As I read your earlier messages, you can ping/ssh/etc. from your PC to your
> phone correctly in the same network setup. Can you confirm this for me? If
> so, we've pinpointed the issue somewhat (although hard to test for me).

Not the OP but also the same problem here. Using a VPN on my android phone
results in the same result with not being able to connect. I can confirm that I
can ping my phone from my pc with no issue.

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Matthijs Tijink]

https://bugs.kde.org/show_bug.cgi?id=375644

--- Comment #8 from Matthijs Tijink  ---
Sorry for the late reaction, I've been busy.

What the PC log message means: the PC received the UDP packet from the phone
and tries to connect to the phone (using TCP). That fails (maybe because of the
thing I mentioned, maybe not), so it tries the reverse: it sends out an UDP
message so the phone will instead connect to the PC. As your issue indicates,
that doesn't work either.

Since the android log does not contain a message that it received an UDP
package, the direction UDP/TCP from PC to phone does not work.

As I read your earlier messages, you can ping/ssh/etc. from your PC to your
phone correctly in the same network setup. Can you confirm this for me? If so,
we've pinpointed the issue somewhat (although hard to test for me).

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Keith Zubot-Gephart]

https://bugs.kde.org/show_bug.cgi?id=375644

Keith Zubot-Gephart  changed:

   What|Removed |Added

 CC||keit...@gmail.com

--- Comment #7 from Keith Zubot-Gephart  ---
Created attachment 109920
  --> https://bugs.kde.org/attachment.cgi?id=109920=edit
logcat output while hitting refresh in the Android app

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Keith Zubot-Gephart]

https://bugs.kde.org/show_bug.cgi?id=375644

--- Comment #6 from Keith Zubot-Gephart  ---
(In reply to Matthijs Tijink from comment #5)
> I think the problem might be that connecting to a server which is remotely
> connected through VPN is impossible (after all: how should the VPN know
> which remote VPN connection it should go to?). KDE Connect works by sending
> an UDP broadcast as you mentioned, and direct UDP packets to the configured
> ip addresses (only on Android). The other device reacts by setting up a TCP
> connection to the source of the UDP packet. So both devices act like a
> server in this setting up process. I hope it's somewhat clear what I mean.

Sure, but everything there except for the UDP broadcast works completely fine
via the VPN connection; I can send TCP and UDP packets between remote and local
machines just fine using their addresses, and I can't see what the UDP
broadcast could possibly be for other than discovering the addresses to
potentially send to; if you tell it precisely the address, why not use that
address? Figuring out where to route the traffic to when given an address to
use is the networking stack's job, not the software's job. And in my testing,
manually sending UDP packets over the VPN to specific addresses has worked
fine.

Anyways, though, I've given your testing steps a shot---thanks very much for
bringing that up, I should have thought of that myself! My initial finding is
that I see the following error from kdeconnectd twice whenever I hit "refresh"
on the Android app:

kdeconnect.core: Fallback (1), try reverse connection (send udp packet)
"Connection refused"

I'll attach the logcat output from the same brief timeframe.

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Matthijs Tijink]

https://bugs.kde.org/show_bug.cgi?id=375644

--- Comment #5 from Matthijs Tijink  ---
I think the problem might be that connecting to a server which is remotely
connected through VPN is impossible (after all: how should the VPN know which
remote VPN connection it should go to?). KDE Connect works by sending an UDP
broadcast as you mentioned, and direct UDP packets to the configured ip
addresses (only on Android). The other device reacts by setting up a TCP
connection to the source of the UDP packet. So both devices act like a server
in this setting up process. I hope it's somewhat clear what I mean.

But we can do something to see what really happens. Can you send the following
logs (both is best, but may not be necessary):
Desktop:
 1. Kill the running kdeconnectd process
 2. Run "/usr/lib/x86_64-linux-gnu/libexec/kdeconnectd" from the command line
and copy the output. Try refreshing from both the Android app and from the
desktop KDE Connect settings.

Android:
 1. Connect your phone using USB to any computer, and run "adb logcat". A lot
of output will appear, but anything before you open KDE Connect is irrelevant.
You may need to install some packages to run the "adb" command.
 2. Try refreshing from both the Android app and from the desktop KDE Connect
settings and copy the resulting log.

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Keith Zubot-Gephart]

https://bugs.kde.org/show_bug.cgi?id=375644

--- Comment #4 from Keith Zubot-Gephart  ---
It's not just a matter of UDP. I can communicate via UDP between clients on the
VPN and computers physically on the network being connected into. For instance,
if I run a UDP iperf server instance on a PC in the office, a remote computer
connecting via our VPN (which is specifically: OpenVPN, device TUN, protocol
TCP) can connect to it just fine.

The problem would appear to be that TUN doesn't support broadcasting across
subnets, and KDE Connect apparently uses UDP broadcasting; see
https://community.kde.org/KDEConnect#I_have_two_devices_running_KDE_Connnect_on_the_same_network.2C_but_they_can.27t_see_each_other.
So yes, the VPN does not route these *specific* UDP packets, even though UDP is
supported in general, but it's weird to me that this is a problem. What is the
point of being able to specify addresses if it will refuse to try those and
rely on the same UDP broadcasting approach to discover other instances anyways?

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Matthijs Tijink]

https://bugs.kde.org/show_bug.cgi?id=375644

Matthijs Tijink  changed:

   What|Removed |Added

 CC||matthijstij...@gmail.com

--- Comment #3 from Matthijs Tijink  ---
Some thoughts of what happens (not 100% sure this is correct): KDE Connect
tries to discover other devices using UDP. If it receives UDP packets of other
KDE Connect devices it tries to connect to them with TCP. So I'd guess that the
VPN does not route the UDP packets to the other peer. Maybe you can check how
UDP behaves on the VPN?

Regarding the home network, I'm not sure what you want to achieve:
 - Do you want to disallow connecting directly over Wifi when you're connected
to a VPN?
 - Do you want the devices to connect over the VPN?

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=375644

g...@gabeappleton.me changed:

   What|Removed |Added

 CC||g...@gabeappleton.me

--- Comment #2 from g...@gabeappleton.me ---
My uneducated guess would be that they aren't scanning all the local addresses
(ie 10.10.*.*)

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[kdeconnect] [Bug 375644] Unable to pair kdeconnect when connecting via OpenVPN, even if specifying hostname or IP address

[Keith Zubot-Gephart]

https://bugs.kde.org/show_bug.cgi?id=375644

--- Comment #1 from Keith Zubot-Gephart  ---
Addendum: I have tried connecting both my home PC and my Nexus 6P to my work
VPN. As long as both are "physically" (somewhat figurative in the case of the
phone, but you know) on my local LAN, then they still see eachother, regardless
of their respective states in regard to the VPN. If I disconnect my phone from
my home wireless yet still connect it to the work VPN, they cease seeing
eachother through KDE Connect. Everything else I can think to try (ping, ssh,
sftp) acts as expected, ie. works if they're ostensibly connected to the same
network via the VPN (or are both not connected to the VPN but via my home
network) and doesn't work if one is connected to the VPN and the other isn't.

What dark sorcery is at work here? (Or alternatively---as it is I who runs the
work OpenVPN instance---what weird edge case with OpenVPN+kdeconnect could I be
running into here in terms of failing to actually route traffic through the
VPN?)

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