Amazon Linux 2 AMIs may contain additional scripts installed by AWS, known as ec2-net-utils. These scripts optionally automate the configuration of your network interfaces. These scripts are available for AL2 only.
Note
For Amazon Linux 2023, the amazon-ec2-net-utils package generates
interface-specific configurations in the /run/systemd/network
directory. For more information, see Networking service in the
Amazon Linux 2023 User Guide.
Use the following command to install the package on AL2 if it's not already installed, or update it if it's installed and additional updates are available:
$yum install ec2-net-utils
The following components are part of ec2-net-utils:
- udev rules (
/etc/udev/rules.d) -
Identifies network interfaces when they are attached, detached, or reattached to a running instance, and ensures that the hotplug script runs (
53-ec2-network-interfaces.rules). Maps the MAC address to a device name (75-persistent-net-generator.rules, which generates70-persistent-net.rules). - hotplug script
-
Generates an interface configuration file suitable for use with DHCP (
/etc/sysconfig/network-scripts/ifcfg-ethN). Also generates a route configuration file (/etc/sysconfig/network-scripts/route-ethN). - DHCP script
-
Whenever the network interface receives a new DHCP lease, this script queries the instance metadata for Elastic IP addresses. For each Elastic IP address, it adds a rule to the routing policy database to ensure that outbound traffic from that address uses the correct network interface. It also adds each private IP address to the network interface as a secondary address.
- ec2ifup ethN (
/usr/sbin/) -
Extends the functionality of the standard ifup. After this script rewrites the configuration files
ifcfg-ethN androute-ethN, it runs ifup. - ec2ifdown ethN (
/usr/sbin/) -
Extends the functionality of the standard ifdown. After this script removes any rules for the network interface from the routing policy database, it runs ifdown.
- ec2ifscan (
/usr/sbin/) -
Checks for network interfaces that have not been configured and configures them.
This script isn't available in the initial release of ec2-net-utils.
To list any configuration files that were generated by ec2-net-utils, use the following command:
$ls -l /etc/sysconfig/network-scripts/*-eth?
To disable the automation, you can add EC2SYNC=no to the
corresponding ifcfg-ethN file. For
example, use the following command to disable the automation for the eth1
interface:
$sed -i -e 's/^EC2SYNC=yes/EC2SYNC=no/' /etc/sysconfig/network-scripts/ifcfg-eth1
To disable the automation completely, you can remove the package using the following command:
$yum remove ec2-net-utils
