diff --git a/cli/setup.go b/cli/setup.go
index 3c7adca0..8993a14e 100644
--- a/cli/setup.go
+++ b/cli/setup.go
@@ -16,6 +16,7 @@ package cli
 
 import (
 	"fmt"
+	"net"
 	"os"
 	"regexp"
 	"strings"
@@ -142,6 +143,16 @@ func setup() {
 		opts.Auth.Pass = string(rand.New(20))
 	}
 
+	//
+
+	for _, cidr := range opts.Auth.Addr {
+		_, subn, err := net.ParseCIDR(cidr)
+		if err != nil {
+			log.Fatalf("Invalid cidr %s. Please specify a valid CIDR address for --auth-addr", cidr)
+		}
+		opts.Auth.Nets = append(opts.Auth.Nets, subn)
+	}
+
 	// --------------------------------------------------
 	// Nodes
 	// --------------------------------------------------
diff --git a/cli/start.go b/cli/start.go
index 74c72e95..513f55b3 100644
--- a/cli/start.go
+++ b/cli/start.go
@@ -70,7 +70,7 @@ func init() {
 	startCmd.PersistentFlags().StringVarP(&opts.Auth.Auth, "auth", "a", "root:root", "Master database authentication details.")
 	startCmd.PersistentFlags().StringVar(&opts.Auth.User, "auth-user", "", "The master username for the database. Use this as an alternative to the --auth flag.")
 	startCmd.PersistentFlags().StringVar(&opts.Auth.Pass, "auth-pass", "", "The master password for the database. Use this as an alternative to the --auth flag.")
-	startCmd.PersistentFlags().StringSliceVar(&opts.Auth.Addr, "auth-addr", nil, "The IP address ranges from which master authentication is possible.")
+	startCmd.PersistentFlags().StringSliceVar(&opts.Auth.Addr, "auth-addr", []string{"0.0.0.0/0"}, "The IP address ranges from which master authentication is possible.")
 
 	startCmd.PersistentFlags().StringVar(&opts.Cert.Crt, "cert-crt", "", "Path to the server certificate. Needed when running in secure mode.")
 	startCmd.PersistentFlags().StringVar(&opts.Cert.Key, "cert-key", "", "Path to the server private key. Needed when running in secure mode.")
diff --git a/cnf/cnf.go b/cnf/cnf.go
index 927e445b..877cdbff 100644
--- a/cnf/cnf.go
+++ b/cnf/cnf.go
@@ -14,7 +14,10 @@
 
 package cnf
 
-import "time"
+import (
+	"net"
+	"time"
+)
 
 var Settings *Options
 
@@ -69,6 +72,7 @@ type Options struct {
 		User string // Master authentication username
 		Pass string // Master authentication password
 		Addr []string
+		Nets []*net.IPNet
 	}
 
 	Node struct {
diff --git a/web/auth.go b/web/auth.go
index b12111c4..0cb69ea0 100644
--- a/web/auth.go
+++ b/web/auth.go
@@ -16,6 +16,7 @@ package web
 
 import (
 	"fmt"
+	"net"
 
 	"bytes"
 	"strings"
@@ -32,7 +33,20 @@ import (
 	"github.com/gorilla/websocket"
 )
 
+func cidr(ip net.IP, networks []*net.IPNet) bool {
+	for _, network := range networks {
+		if network.Contains(ip) {
+			return true
+		}
+	}
+	return false
+}
+
 func auth() fibre.MiddlewareFunc {
+
+	user := []byte(cnf.Settings.Auth.User)
+	pass := []byte(cnf.Settings.Auth.Pass)
+
 	return func(h fibre.HandlerFunc) fibre.HandlerFunc {
 		return func(c *fibre.Context) (err error) {
 
@@ -115,10 +129,8 @@ func auth() fibre.MiddlewareFunc {
 
 				base, err := base64.StdEncoding.DecodeString(head[6:])
 
-				if err == nil {
+				if err == nil && cidr(c.IP(), cnf.Settings.Auth.Nets) {
 
-					user := []byte(cnf.Settings.Auth.User)
-					pass := []byte(cnf.Settings.Auth.Pass)
 					cred := bytes.SplitN(base, []byte(":"), 2)
 
 					if len(cred) == 2 && bytes.Equal(cred[0], user) && bytes.Equal(cred[1], pass) {