Linux - hostonlif ipconfig modifies system default route

[cssolomonides]

Hello,

creating a hostonlyif and assigning an IP to it via vboxmanage hostonlyif ipconfig vboxnet0 --ip 192.168.56.1 results in mangling the host system routing, giving maximum priority to the hostonly interface for default route.

$ vboxmanage --version
6.1.6_Ubuntur137129

$ ip route ls
default via 192.168.10.1 dev wlan0 proto dhcp src 192.168.10.4 metric 303 mtu 1500

$ vboxmanage hostonlyif create
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Interface 'vboxnet0' was successfully created

$ ip route ls
default via 192.168.10.1 dev wlan0 proto dhcp src 192.168.10.4 metric 303 mtu 1500

$ vboxmanage hostonlyif ipconfig vboxnet0 --ip 192.168.56.1

$ ip route ls
default via 192.168.56.1 dev vboxnet0 src 192.168.56.1 metric 212
default via 192.168.10.1 dev wlan0 proto dhcp src 192.168.10.4 metric 303 mtu 1500

As this behavior mangles system network connectivity, it would be expected that the default route created by the hostif network has lower priority compared to existing ones.

[Valery Ushakov]

This is strange. All it does, is, effectively:

# ip link set dev vboxnet0 up
# ip addr add 192.168.56.1/24 broadcast 192.168.56.255 dev vboxnet0

You can verify this by running

strace -f .../VBoxNetAdpCtl vboxnet0 192.168.56.1 netmask 255.255.255.0 2>&1 > /dev/null | grep 'exec.*/sbin/ip'

(where VBoxNetAdpCtl is in the vbox internal bin dir, whereever that is in the package).

[cssolomonides]

You may close as invalid. This was due to leftover configuration to a dhcpcd server that set the route for vboxnet0