Bogus default gateway keeps appearing

[Zebulon Walton]

you might find sometihing within `/etc/NetworkManager`
sudo grep -rF 192.168.225. /etc/NetworkManager/

Good idea, but it turns out there are no references to that subnet there or in /etc/network. Just for grins I searched all of /etc and nothing turned up.

However, I searched /var and found in /var/lib/NetworkManager there are a bunch of files that contain references to that subnet. They have names in this format:

Code:

internal-xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx-enxxxxxxxxxxxxx.lease

...where the "x" characters are hex numbers. They are different for each file. The "enx" numbers at the end which appeared to be MAC addresses are also different in each one, so possibly this is a virtual adapter created on the fly? (I thought the adapter name in the routing table looked different this time!)

Contents of each of those files (apparently DHCP leases since they have the extension of .lease) look like this, with a different last 192.168.225.x octet in each:

Code:

# This is private data. Do not parse.

ADDRESS=192.168.225.29

So, apparently Network Manager is pulling these addresses from somewhere and installing a matching default route. (Currently there are 25 of these files in /var/lib/NetworkManager.) Another interesting thing is I've found that while the internet cannot be accessed while that route is in place, the address 192.168.225.1 responds to pings.

There is also a NetworkManager-intern.conf file which contains only comments, no active settings. Additionally there's a NetworkManager.state file containing the following:

Code:

[main]
NetworkingEnabled=true
WirelessEnabled=true
WWANEnabled=false

I read this as saying NetworkManager is aware that cellular internet is disabled.

Further, if I use ethtool to probe the enx* adapter, the following is reported. The speed reported appears to correspond to a USB2 connection:

Code:

Settings for enxxxxxxxxxxxxx:
Supported ports: [  ]
Supported link modes:  Not reported
Supported pause frame use: No
Supports auto-negotiation: No
Supported FEC modes: Not reported
Advertised link modes:  Not reported
Advertised pause frame use: No
Advertised auto-negotiation: No
Advertised FEC modes: Not reported
Speed: 425Mb/s
Duplex: Half
Auto-negotiation: off
Port: Twisted Pair
PHYAD: 0
Transceiver: internal
MDI-X: Unknown
        Current message level: 0x00000007 (7)
                              drv probe link
Link detected: yes
Supported ports: [  ]
Supported link modes:  Not reported
Supported pause frame use: No
Supports auto-negotiation: No
Supported FEC modes: Not reported
Advertised link modes:  Not reported
Advertised pause frame use: No
Advertised auto-negotiation: No
Advertised FEC modes: Not reported
Speed: 425Mb/s
Duplex: Half
Auto-negotiation: off
Port: Twisted Pair
PHYAD: 0
Transceiver: internal
MDI-X: Unknown
        Current message level: 0x00000007 (7)
                              drv probe link
Link detected: yes

However, the USB tethering adapter shows up as usb0, and ethtool only reports the following for it:

Code:

Settings for usb0:

Link detected: yes

So more clues here and it appears that NetworkManager is doing this but I still don't know why.