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internet access to VM 1 external IP

asked 2019-10-07 04:31:21 -0500

jef00 gravatar image

We have to install an Openstack for our school project. We have chosen CentOS as the operating system. Now we have decided with the group members that we rent a dedicated server from a hosting party. Now we have 2 external IPs one is used for the host and one we want to use for the VMs within Openstack. Now we want to know if it is possible to use an external IP for all VMs within Openstack

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answered 2019-10-07 17:10:20 -0500

updated 2019-10-07 21:04:31 -0500

You can assign the external IP to one VM at a time. You can also remove it from one VM and assign it to another (this is were the OpenStack and AWS term floating IP comes from: The IP address "floats" from one VM to the other).

But you cannot assign it to two or more VMs at the same time.

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thank you for answer!, if the external IP is for the hoost and the for the VMs that is possible within Openstack

jef00 gravatar imagejef00 ( 2019-10-08 09:01:50 -0500 )edit

Yes, absolutely. You need to configure the floating IP range (a range consisting of a single address) when creating the subnet for the external betwork.

By the way, see the other answer: You don't need a floating IP to access the internet from your VMs.

Bernd Bausch gravatar imageBernd Bausch ( 2019-10-09 03:36:04 -0500 )edit

answered 2019-10-09 01:16:07 -0500


You can configure external network with this Your external IP address as external gateway IP. You can than connect Your instances to this router and do SNAT with this IP address. That way many instances can have access to the internet using this one IP. But You will not have access to those instances that way.

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Asked: 2019-10-07 04:31:21 -0500

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Last updated: Oct 07 '19