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03/06/2019

How to find ip address of Linux KVM guest virtual machine



How do I find out an IP address of Linux KVM guest from Linux host itself? I wanted to ssh into KVM guest VM. How can I find the IP address of a KVM Virtual Machine Guest on a CentOS Linux 7.x server?

There are various ways to get the IP address of KVM guest from the host. If you are using virbr0 (default bridge) use the virsh command. It is also possible to use the combination of arp command or check DHCP server log if you are using a dedicated DHCPD over a bridged network such as br0 that give access to physical LAN.

Steps to find the ip address of Linux KVM guest virtual machine

  1. Open the terminal app or login using ssh to host server
  2. Get the network list: virsh net-list
  3. Type the command: virsh net-dhcp-leases networkNameHere

Let us see steps in details.

Method 1 – Find the IP addresses of VMs in KVM with virsh

Type the following command to list network:
# virsh net-list
# virsh net-info default
# virsh net-dhcp-leases default


You can type ssh command to log in to OpenBSD VM named nixcraft-openbsd with IP address 192.168.122.124:
$ ssh vivek@192.168.122.124

Method 2 – Get the IP address of Linux KVM guest using domifaddr

Find network interfaces’ addresses for a running domain called freebsd11.1:
$ virsh list
$ virsh domifaddr freebsd11.1

Combine both virsh and bash shell while loop as follows:

virsh list --name | while read n 
do 
  [[ ! -z $n ]] && virsh domifaddr $n
done

virsh list –name | while read n do [[ ! -z $n ]] && virsh domifaddr $n done

Method 3 – Use arp command to g a KVM guest’s IP address

Use the virsh command to find out the mac address of domain:
$ virsh list
$ virsh dumpxml VM_NAME | grep "mac address" | awk -F' '{ print $2}'
$ arp -an | grep 52:54:00:ce:8a:c4

In short use any one of the following virsh command to get the ip address

$ virsh list
$ virsh domifaddr rhel7

Say hello to Libvirt NSS module

When it comes to managing guests and executing commands inside them, logging into guest operating system and doing the job is convenient. Users are used to ssh in this case. Ideally,
ssh user@ip-Address-Here
But depending on virtual network configuration it might not be always possible. For instance, when using libvirt NATed network it’s dnsmasq (spawned by libvirt) who assigns IP addresses to domains. But by default, the dnsmasq process is then not consulted when it comes to host name translation. Users work around this problem by configuring their libvirt network to assign static IP addresses and maintaining /etc/hosts file in sync. But this puts needless burden onto users. This is where NSS module comes handy.

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Posted by: SXI ADMIN

The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.

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