Bug 447402

Summary:	Using ethernet connection plasma networking doesn't setup default route to gateway
Product:	[KDE Neon] neon	Reporter:	Nick <nick.craig.law>
Component:	Packages User Edition	Assignee:	Neon Bugs <neon-bugs>
Status:	RESOLVED FIXED
Severity:	normal	CC:	jr, neon-bugs, nick.craig.law, sitter
Priority:	NOR
Version:	unspecified
Target Milestone:	---
Platform:	Neon
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	No default route

Description Nick 2021-12-22 22:53:37 UTC

SUMMARY
***
This is a problem you won't see if you only use wifi, however if you use ethernet via the RJ45 connector then maybe you will have this problem.

If you plug into a network using an ethernet wired connection (with WIFI disabled) and have DHCP setup in the plasma network configuration. When the system obtains it's IP address it fails to setup the default gateway so no internet access is available. If you type route add default gw 192.168.0.1 enp2s0 then everything then works.

How come the gateway is no longer setup in the routing table automatically when hot plugging an ethernet cable?

WIFI works fine.

routing table after ethernet cable plugged in.

route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
link-local      0.0.0.0         255.255.0.0     U     1000   0        0 virbr0
192.168.1.0     0.0.0.0         255.255.255.0   U     100    0        0 enp2s0
192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

Below is the routing table for WIFI showing the extra line starting with 'default'

route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         _gateway        0.0.0.0         UG    600    0        0 wlp3s0
link-local      0.0.0.0         255.255.0.0     U     1000   0        0 virbr0
192.168.1.0     0.0.0.0         255.255.255.0   U     600    0        0 wlp3s0
192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0
***


STEPS TO REPRODUCE
100% reproducible on my laptop 

OBSERVED RESULT
No default gateway setup in routing table

EXPECTED RESULT
default route should be added when ethernet cable used.

SOFTWARE/OS VERSIONS
Operating System: KDE neon 5.23
KDE Plasma Version: 5.23.4
KDE Frameworks Version: 5.89.0
Qt Version: 5.15.3
Kernel Version: 5.11.0-43-generic (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Core™ i7-2670QM CPU @ 2.20GHz
Memory: 15.6 GiB of RAM
Graphics Processor: GeForce GTX 570M/PCIe/SSE2

ADDITIONAL INFORMATION

Comment 1 Nick 2021-12-22 23:04:22 UTC

Created attachment 144793 [details]
No default route

If you have "Use only for resources on this connection" then the default route for that connection won't get setup and you won't have internet access. Untick if this connection is your route to the internet. The message could may be a bit clearer in regards to disabling the default route and it's consequence.

Comment 2 Nick 2021-12-22 23:05:44 UTC

See above comment and attachment. Closing. Not a bug.