Allow disabling custom routing (#1840)

iface/wg_configurer_kernel.go

@@ -10,8 +10,6 @@ import (
 	log "github.com/sirupsen/logrus"
 	"golang.zx2c4.com/wireguard/wgctrl"
 	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
-
-	nbnet "github.com/netbirdio/netbird/util/net"
 )
 
 type wgKernelConfigurer struct {
@@ -31,7 +29,7 @@ func (c *wgKernelConfigurer) configureInterface(privateKey string, port int) err
 	if err != nil {
 		return err
 	}
-	fwmark := nbnet.NetbirdFwmark
+	fwmark := getFwmark()
 	config := wgtypes.Config{
 		PrivateKey:   &key,
 		ReplacePeers: true,

iface/wg_configurer_usp.go

@@ -349,7 +349,7 @@ func toWgUserspaceString(wgCfg wgtypes.Config) string {
 }
 
 func getFwmark() int {
-	if runtime.GOOS == "linux" {
+	if runtime.GOOS == "linux" && !nbnet.CustomRoutingDisabled() {
 		return nbnet.NetbirdFwmark
 	}
 	return 0