An external network modifier (ENM) is a type of network profile that manages applications that are responsible for creating network configuration that is external to the system's primary network configuration.
ENMs enable you to specify when applications or scripts should perform network or any other system configuration. ENMs can also be defined as services or applications that directly modify your network configuration when they are enabled or disabled. You can specify the conditions under which an ENM should be enabled or disabled, and you can also enable or disable an ENM manually. Multiple ENMs can potentially be active on the system at the same time.
You can create ENMs for several external applications and services. However, the obvious application of ENMs is on a virtual private network (VPN). After you install and configure VPN on your system, you can create an ENM that automatically activates and deactivates VPN under the conditions that you specify.
All ENMs have an activation-mode property. You set the activation-mode property when you create or modify an ENM with the netcfg command.
You can set the following values for this property:
manual – Enabled and disabled by using the netadm command.
conditional-any – Enabled and disabled by the system, based on the changes in the conditions of the ENM.
conditional-all – Enabled and disabled by the system, based on changes in the conditions of the ENM.
Changes in the network environment cause the system to reevaluate conditions for the ENM. These changes include plugging or unplugging an Ethernet cable, obtaining or losing a DHCP lease, detecting a new wireless network, and so on.