I installed VirtualBox when I was running Ubuntu GNOME 15.10 with GNOME 3.18 from the official repository (details are given on the official site), however when I upgraded to Ubuntu GNOME 16.04 with GNOME 3.20 I found that the new kernel did not allow unsigned kernel modules and as Oracle doesn't sign them (or at least didn't back then, I don't know about now) they can't be run. So I purged it using apt-get (or maybe I used remove, but I don't remember).
But now I am concerned that it has left something behind for when I run the networkctl this is the output:
IDX LINK TYPE OPERATIONAL SETUP
1 lo loopback n/a n/a
2 enp3s0 ether n/a n/a
3 wlp2s0b1 wlan n/a n/a
4 virbr0 ether n/a n/a
5 virbr0-nic ether n/a n/a
5 links listed.
And here is part of the output from ifconfig:
virbr0 Link encap:Ethernet HWaddr 00:00:00:00:00:00
inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
It seems to be named similar to the VirtualBox standard, so is this something left behind from VirtualBox or something else? If it is from VirtualBox then can I safely and cleanly remove it and will there be anything else left in my system? Also, could it cause me any harm if it just stays there as it is?