Member Avatar for lewashby

I ran the command ifconfig and in addition to lo and eth0 I got this item that I have never seen before. Can anyone tell me what it is?

virbr0 Link encap:Ethernet HWaddr da:1c:6c:2a:cb:80
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:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

Edited by lewashby because: miss spelled something
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  • Latest Post Latest Post by tnhjennis

Dani AI

Generated

Short answer: that virbr0 is almost certainly the libvirt-managed virtual bridge used for the default NAT network (KVM/QEMU). The default libvirt network creates an isolated bridge (typically with gateway 192.168.122.1), inserts iptables rules and runs a per-network dnsmasq for DHCP/DNS. (wiki.libvirt.org)

Quick checks to confirm origin (run as root or with sudo):

ip addr show virbr0
brctl show               # or: ip link show type bridge
virsh net-list --all
ps aux | egrep 'libvirtd|qemu|dnsmasq'
# Debian/Ubuntu:
dpkg -l | grep -i libvirt
# RHEL/CentOS:
rpm -qa | grep -i libvirt

virsh net-list --all will show the libvirt networks and their autostart status. (download.libvirt.org)

If you want it gone (careful: this will break VM networking), the common commands are:

# stop the running default network (removes virbr0 until libvirt restarts it)
sudo virsh net-destroy default

# prevent it from auto-starting on libvirt daemon start
sudo virsh net-autostart default --disable

# remove the persistent network definition
sudo virsh net-undefine default

# optionally stop/disable libvirt daemon:
sudo systemctl stop libvirtd
sudo systemctl disable libvirtd   # service name may be libvirt-bin on older systems

virsh net-destroy/net-undefine and net-autostart are the supported ways to manage the default network; libvirt will also remove the bridge and dnsmasq when the network is destroyed. (download.libvirt.org)

Notes tied to earlier replies: and were on the right track (virtual/NAT bridge). ’s VirtualBox idea is less likely here — VirtualBox host-only interfaces usually appear as vboxnet0 rather than virbr0. Check packages before removing anything so you don’t accidentally disrupt guests you didn’t know were running. ()

Recommended Answers

All 6 Replies

Member Avatar for rch1231

Looks like some sort of Virtual NIC. Are you on a virtual system (ESX guest) or running any virtual software on the server?

Member Avatar for L7Sqr

It might be NAT related

Member Avatar for CimmerianX

This is common when you run a virtual environment on the same host. Do you have Virtual Box installed on this host by any chance?

Member Avatar for lewashby

No, it's just a computer with a few LFS systems on it. I built two LFS systems, resized a partition and then installed ubuntu server.

Member Avatar for naphets

su root
ps -e | grep ubuntuone
kill above id's
I am guessing it is their cloud.. which is why i went to Mint.

Member Avatar for tnhjennis

Appears to be bridging interface. Did you install any new program recently?

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