How the NWAM Configuration Works

NWAM's default behavior is to perform basic configuration of your wired or wireless network “automagically”, without any user interaction. The only time you are required to interact with NWAM is if you are prompted by the system for more information, for example, to provide a security key or password for a wireless network.

The automated NWAM configuration is triggered by the following events and activities:

• Connecting or disconnecting an Ethernet cable

• Connecting or disconnecting a WLAN card

• Booting a system when a wired interface, a wireless interface, or both, is available

• Resuming from suspend when a wired interface, a wireless interface, or both, is available (if supported)

• Acquiring or losing a DHCP lease

The NWAM components interact with each other in the following manner:

• At all times, one NCP and one Location profile must be active on the system.

• During a system boot, the policy engine daemon, nwamd, performs the following actions:

  1. Consults the service property for the currently active NCP

  2. Proceeds until one or more IP addresses have been configured

  3. Checks the conditions of the Location profiles

  4. Activates the Location profile that is specified by the policy engine

  5. Configures the network, or networks, accordingly

• As events that might trigger a change in the network configuration occur, the NWAM daemon, nwamd, functions in various roles and performs the following operations:

  1. As an event handler, nwamd detects each event as it occurs.

  2. As a profile daemon, nwamd consults the active profile.

  3. Depending on the change, nwamd might reconfigure the network, or networks, accordingly.

NWAM Default Behavior

In the absence of user-defined network profiles, nwamd manages network configuration based on the following three system-defined profiles:

• Automatic NCP

• Automatic location

• NoNet location

The Automatic NCP implements the following basic policy:

• Configure all available (connected) Ethernet interfaces by using DHCP.

• If no Ethernet interfaces are connected, or if none can obtain an IP address, activate one wireless interface, automatically connecting to the best available WLAN from the Known WLAN list. Or, wait for the user to select a wireless network to connect to.

• Until at least one IPv4 address has been obtained, the NoNet location remains active. This Location profile provides a strict set of IP Filter rules that only pass data that is relevant to IP address acquisition (DHCP and IPv6 autoconf messages). All of the properties of the NoNet location, with the exception of the activation conditions, can be modified.

• When at least one IPv4 address has been assigned to one of the system's interfaces, the Automatic location is activated. This Location profile has no IP Filter or IPsec rules. The Location profile applies the DNS configuration data that is obtained from the DHCP server. As with the NoNet location, all of the properties of the Automatic location, with the exception of its activation conditions, can be modified.

• The NoNet location is always applied when the system has no IPv4 addresses assigned to it. When there is at least one IPv4 address assigned, the system selects the Location profile with the activation rules that best match the current network conditions. In the absence of a better match, the system falls back to the Automatic location. For more information, see How NWAM Profiles Are Activated.