How to Configure OpenStack Network to Enable Access to OpenStack Instances

This tutorial will guide you on how you can configure OpenStack networking service in order to allow access from external networks to OpenStack instances.

Requirements

1. Install OpenStack in RHEL and CentOS 7

Step 1: Modify Network Interface Configuration Files

1. Before starting to create OpenStack networks from dashboard, first we need to create an OVS bridge and modify our physical network interface to bind as a port to OVS bridge.

Thus, login to your server terminal, navigate to network interfaces directory scripts and use the physical interface as an excerpt to setup OVS bridge interface by issuing the following commands:

# cd /etc/sysconfig/network-scripts/
# ls  
# cp ifcfg-eno16777736 ifcfg-br-ex

2. Next, edit and modify the bridge interface (br-ex) using a text editor as illustrated below:

# vi ifcfg-br-ex

Interface br-ex excerpt:

TYPE="Ethernet"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="no"
IPV6_AUTOCONF="no"
IPV6_DEFROUTE="no"
IPV6_FAILURE_FATAL="no"
NAME="br-ex"
UUID="1d239840-7e15-43d5-a7d8-d1af2740f6ef"
DEVICE="br-ex"
ONBOOT="yes"
IPADDR="192.168.1.41"
PREFIX="24"
GATEWAY="192.168.1.1"
DNS1="127.0.0.1"
DNS2="192.168.1.1"
DNS3="8.8.8.8"
IPV6_PEERDNS="no"
IPV6_PEERROUTES="no"
IPV6_PRIVACY="no"

3. Do the same with the physical interface (eno16777736), but make sure it looks like this:

# vi ifcfg-eno16777736

Interface eno16777736 excerpt:

TYPE="Ethernet"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="no"
IPV6_AUTOCONF="no"
IPV6_DEFROUTE="no"
IPV6_FAILURE_FATAL="no"
NAME="eno16777736"
DEVICE="eno16777736"
ONBOOT="yes"
TYPE=”OVSPort”
DEVICETYPE=”ovs”
OVS_BRIDGE=”br-ex”

Important: While editing interfaces cards make sure you replace the physical interface name, IPs and DNS servers accordingly.

4. Finally, after you’ve modified edited both network interfaces, restart network daemon to reflect changes and verify the new configurations using ip command.

# systemctl restart network.service
# ip a

Step 2: Create a New OpenStack Project (Tenant)

5. On this step we need to use Openstack dashboard in order to further configure our cloud environment.

Login to Openstack web panel (dashboard) with admin credentials and go to Identity -> Projects -> Create Project and create a new project as illustrated below.

6. Next, navigate to Identity -> Users -> Create User and create a new user by filling all the fields with the required information.

Assure that this new user has the Role assigned as a _member_ of the newly created tenant (project).

Step 3: Configure OpenStack Network

7. After the user has been created, log out admin from dashboard and log in with the new user in order to create two networks (internal network and external).

Navigate to Project -> Networks -> Create Network and setup the internal network as follows:

Network Name: internal
Admin State: UP
Create Subnet: checked

Subnet Name: internal-tecmint
Network Address: 192.168.254.0/24
IP Version: IPv4
Gateway IP: 192.168.254.1

DHCP: Enable

Use the below screenshots as a guide. Also, replace the Network Name, Subnet Name and IP addresses with your own custom settings.

8. Next, use the same steps as above to create the external network. Make sure the IP address space for external network is in the same network range as your uplink bridge interface IP address range in order to work properly without extra routes.

Therefore, if the br-ex interface has 192.168.1.1 as a default gateway for 192.168.1.0/24 network, the same network and gateway IPs should be configured for external network too.

Network Name: external
Admin State: UP
Create Subnet: checked

Subnet Name: external-tecmint
Network Address: 192.168.1.0/24
IP Version: IPv4
Gateway IP: 192.168.1.1

DHCP: Enable

Again, replace the Network Name, Subnet Name and IP addresses according to your own custom configurations.

9. On the next step we need to log in OpenStack dashboard as admin and mark the external network as External in order to be able to communicate with the bridge interface.

Thus, login with admin credentials and move to Admin -> System-> Networks, click on the external network, check the External Network box and hit on Save Changes to apply the configuration.

When done, logout from admin user and log in with the custom user again to proceed to the next step.

10. Finally, we need to create a router for our two networks in order to move packets back and forth. Go to Project -> Network -> Routers and hit on Create Router button. Add the following settings for the router.

Router Name: a descriptive router name
Admin State: UP
External Network: external 

11. Once the Router has been created you should be able to see it in the dashboard. Click on the router name, go to Interfaces tab and hit on Add Interface button and a new prompt should appear.

Select the internal subnet, leave the IP Address field blank and hit on Submit button to apply changes and after a few seconds your interface should become Active.

12. In order to verify OpenStack network settings, go to Project -> Network -> Network Topology and a network map will be presented as illustrated on the below screenshot.

That’s all! Your OpenStack network is now functional and ready for virtual machines traffic. On the next topic we’ll discuss how to create and launch an OpenStack image instance.