@@ -598,6 +598,16 @@ AC_CHECK_HEADERS(

 	],

 	[have_tap_header="yes"]

 )

+AC_CHECK_DECLS(

+	[TUNSETPERSIST],

+	[AC_DEFINE([ENABLE_FEATURE_TUN_PERSIST], [1], [We have persist tun capability])],

+	,

+	[[

+		#ifdef HAVE_LINUX_IF_TUN_H

+		#include <linux/if_tun.h>

+		#endif

+	]]

+)

 CFLAGS="${old_CFLAGS}"

 test "${have_tap_header}" = "yes" || AC_MSG_ERROR([no tap header could be found])

@@ -954,7 +954,7 @@ do_genkey (const struct options * options)

 bool

 do_persist_tuntap (const struct options *options)

 {

-#ifdef TUNSETPERSIST

+#ifdef ENABLE_FEATURE_TUN_PERSIST

   if (options->persist_config)

     {

       /* sanity check on options for --mktun or --rmtun */

@@ -725,7 +725,7 @@ static const char usage_message[] =

   "                  for use with the --secret option.\n"

   "--secret file   : Write key to file.\n"

 #endif				/* ENABLE_CRYPTO */

-#ifdef TUNSETPERSIST

+#ifdef ENABLE_FEATURE_TUN_PERSIST

   "\n"

   "Tun/tap config mode (available with linux 2.4+):\n"

   "--mktun         : Create a persistent tunnel.\n"

@@ -791,7 +791,7 @@ init_options (struct options *o, const bool init_gc)

   o->management_echo_buffer_size = 100;

   o->management_state_buffer_size = 100;

 #endif

-#ifdef TUNSETPERSIST

+#ifdef ENABLE_FEATURE_TUN_PERSIST

   o->persist_mode = 1;

 #endif

 #ifndef WIN32

@@ -1420,7 +1420,7 @@ show_settings (const struct options *o)

   SHOW_INT (mode);

-#ifdef TUNSETPERSIST

+#ifdef ENABLE_FEATURE_TUN_PERSIST

   SHOW_BOOL (persist_config);

   SHOW_INT (persist_mode);

 #endif

@@ -6788,7 +6788,7 @@ add_option (struct options *options,

       options->pkcs11_id_management = true;

     }

 #endif

-#ifdef TUNSETPERSIST

+#ifdef ENABLE_FEATURE_TUN_PERSIST

   else if (streq (p[0], "rmtun"))

     {

       VERIFY_PERMISSION (OPT_P_GENERAL);

@@ -1517,7 +1517,7 @@ open_tun (const char *dev, const char *dev_type, const char *dev_node, struct tu

 #endif /* HAVE_LINUX_IF_TUN_H */

-#ifdef TUNSETPERSIST

+#ifdef ENABLE_FEATURE_TUN_PERSIST

 /*

  * This can be removed in future

@@ -1567,7 +1567,7 @@ tuncfg (const char *dev, const char *dev_type, const char *dev_node, int persist

   msg (M_INFO, "Persist state set to: %s", (persist_mode ? "ON" : "OFF"));

 }

-#endif /* TUNSETPERSIST */

+#endif /* ENABLE_FEATURE_TUN_PERSIST */

 void

 close_tun (struct tuntap *tt)