@@ -1711,6 +1711,12 @@ open_tun (const char *dev, const char *dev_type, const char *dev_node, struct tu

       msg (M_FATAL, "I don't recognize device %s as a tun or tap device",

 	   dev);

     }

+

+  if ((tt->ip_fd = open (ip_node, O_RDWR, 0)) < 0)

+    msg (M_ERR, "Can't open %s", ip_node);

+

+  if ((tt->fd = open (dev_node, O_RDWR, 0)) < 0)

+    msg (M_ERR, "Can't open %s", dev_node);

   /* get unit number */

   if (*dev)

@@ -1721,19 +1727,37 @@ open_tun (const char *dev, const char *dev_type, const char *dev_node, struct tu

       ppa = atoi (ptr);

     }

-  if ((tt->ip_fd = open (ip_node, O_RDWR, 0)) < 0)

-    msg (M_ERR, "Can't open %s", ip_node);

-

-  if ((tt->fd = open (dev_node, O_RDWR, 0)) < 0)

-    msg (M_ERR, "Can't open %s", dev_node);

-

   /* Assign a new PPA and get its unit number. */

   strioc_ppa.ic_cmd = TUNNEWPPA;

   strioc_ppa.ic_timout = 0;

   strioc_ppa.ic_len = sizeof(ppa);

   strioc_ppa.ic_dp = (char *)&ppa;

-  if ((ppa = ioctl (tt->fd, I_STR, &strioc_ppa)) < 0)

-    msg (M_ERR, "Can't assign new interface");

+

+  if ( *ptr == '\0' )		/* no number given, try dynamic */

+    {

+      bool found_one = false;

+      while( ! found_one && ppa < 64 )

+	{

+	  int new_ppa = ioctl (tt->fd, I_STR, &strioc_ppa);

+	  if ( new_ppa >= 0 )

+	    {

+	      msg( M_INFO, "open_tun: got dynamic interface '%s%d'", dev_tuntap_type, new_ppa );

+	      ppa = new_ppa;

+	      found_one = true;

+	      break;

+	    }

+	  if ( errno != EEXIST )

+	    msg (M_ERR, "open_tun: unexpected error trying to find free %s interface", dev_tuntap_type );

+	  ppa++;

+	}

+      if ( !found_one )

+	msg (M_ERR, "open_tun: could not find free %s interface, give up.", dev_tuntap_type );

+    }

+  else				/* try this particular one */

+    {

+      if ((ppa = ioctl (tt->fd, I_STR, &strioc_ppa)) < 0)

+        msg (M_ERR, "Can't assign PPA for new interface (%s%d)", dev_tuntap_type, ppa );

+    }

   if ((if_fd = open (dev_node, O_RDWR, 0)) < 0)

     msg (M_ERR, "Can't open %s (2)", dev_node);