Client config param added to specify net iface to use for fingerprinting. Added a Golang-native method for determining the interface IP address.

command/agent/agent.go

@@ -192,6 +192,9 @@ func (a *Agent) setupClient() error {
 		conf.AllocDir = a.config.Client.AllocDir
 	}
 	conf.Servers = a.config.Client.Servers
+	if a.config.Client.Iface != "" {
+		conf.Iface = a.config.Client.Iface
+	}
 
 	// Setup the node
 	conf.Node = new(structs.Node)

command/agent/config.go

@@ -139,6 +139,9 @@ type ClientConfig struct {
 
 	// Metadata associated with the node
 	Meta map[string]string `hcl:"meta"`
+
+	// Interface to use for network fingerprinting
+	Iface string `hcl:"iface"`
 }
 
 // ServerConfig is configuration specific to the server mode
@@ -384,6 +387,9 @@ func (a *ClientConfig) Merge(b *ClientConfig) *ClientConfig {
 	if b.NodeClass != "" {
 		result.NodeClass = b.NodeClass
 	}
+	if b.Iface != "" {
+		result.Iface = b.Iface
+	}
 
 	// Add the servers
 	result.Servers = append(result.Servers, b.Servers...)