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How should I configure my Ethernet interfaces for CDRouter Demo?

Configuring System Interfaces for use with CDRouter Demo

CDRouter Demo utilizes three (3) network interfaces, at a minimum. Two are dedicated for use by the CDRouter software during testing. The third may be assigned to a live corporate or lab network connection, to allow remote access to the system running the CDRouter Demo software.

It is strongly recommended that the interface used for the connection to the corporate or lab network remains separate and not used as a test interface.

When a CDRouter Demo test package is run, it relies on the IP configuration information contained in the CDRouter configuration file, not on the Linux host. For this reason, you must have any network interfaces used as test interfaces be in an “unconfigured” state.

Step 1 - Determine the Ethernet Interface Names

As the root user, type the following command in a terminal window"

# ip link

This will return output similar to this: (the specific interface names may be different on your system)

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
    link/ether 00:03:2d:1a:cb:d5 brd ff:ff:ff:ff:ff:ff
3: enp0s8: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
    link/ether 00:03:2d:1a:cb:d6 brd ff:ff:ff:ff:ff:ff
4: enp0s9: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
    link/ether 00:03:2d:1a:cb:d7 brd ff:ff:ff:ff:ff:ff

In the example above, the 3 physical interfaces are named enp0s3, enp0s8, and enp0s9.

Step 2 - Choose and Configure the Management Interface

For the following example, we are choosing enp0s3.

As the root user, use a text editor to create the file: /etc/sysconfig/network-scripts/ifcfg-enp0s3

*The name of the file must be: ifcfg-<interface-name-chosen-on-your-system>


# For DHCP address:

The values assigned to DEVICE and NAME must be the name of the interface chosen on your system.

To have this interface get an IPv4 address via DHCP, set BOOTPROTO to dhcp.

Step 3 - Prevent NetworkManager from Controlling the Other Interfaces

The NetworkManager service is enabled on most Linux systems by default to automatically keep the system’s IP address, default gateway and DNS servers updated when it is connected to the network. Because CDRouter needs to have full control over the system’s network interfaces in order to send and receive traffic, the NetworkManager service should not be configured to manage those interfaces.

Please follow the instructions in the following Knowledge Base article to properly configure NetworkManager to ignore the interfaces used for CDRouter testing:

Prevent Network Manager from controlling an interface

Step 4 - Restart Networking

You may need to restart networking to make changes take effect.

As the root user:

systemctl restart network