--- tun-1.1/linux/2.2/tun.c	2000-10-23 22:13:08.000000000 -0700
+++ tun.new/linux/2.2/tun.c	2005-12-22 00:27:56.000000000 -0800
@@ -180,8 +180,19 @@
 
    poll_wait(file, &tun->read_wait, wait);
  
+   /* Data written to the /dev/tunX device is immediately placed into a socket buffer, making it
+    * available to networking code at the tunX interface.  Writes never block.
+    * Likewise, data flows from the network stack, through the tunX interface and into the /dev/tun* device,
+    * where it is queued, making it available for read().
+    * Thus the character device /dev/tunX is:
+    *   - readable if data was "transmitted" to the tunX interface and is now queued at the /dev/tunX device.
+    *   - always writable.
+    * Everything written here is equally true of taps.
+    * The author made a mistake when implementing this routine; he forgot that the device is always writable.
+    * -jeff stearns 22-Dec-2005
+    */
    if( skb_queue_len(&tun->txq) )
-      return POLLIN | POLLRDNORM;
+      return POLLIN | POLLRDNORM | POLLOUT | POLLWRNORM;
 
    return POLLOUT | POLLWRNORM;
 }
--- tun-1.1/linux/2.4/tun.c	2001-01-09 16:24:24.000000000 -0800
+++ tun.new/linux/2.4/tun.c	2005-12-28 12:28:46.000000000 -0800
@@ -176,9 +176,20 @@
 	DBG(KERN_INFO "%s: tun_chr_poll\n", tun->name);
 
 	poll_wait(file, &tun->read_wait, wait);
- 
+
+   /* Data written to the /dev/tunX device is immediately placed into a socket buffer, making it
+	* available to networking code at the tunX interface.  Writes never block.
+	* Likewise, data flows from the network stack, through the tunX interface and into the /dev/tun* device,
+	* where it is queued, making it available for read().
+	* Thus the character device /dev/tunX is:
+	*   - readable if data was "transmitted" to the tunX interface and is now queued at the /dev/tunX device.
+	*   - always writable.
+	* Everything written here is equally true of taps.
+	* The author made a mistake when implementing this routine; he forgot that the device is always writable.
+	* -jeff stearns 22-Dec-2005
+	*/
 	if (skb_queue_len(&tun->txq))
-		return POLLIN | POLLRDNORM;
+		return POLLIN | POLLRDNORM | POLLOUT | POLLWRNORM;
 
 	return POLLOUT | POLLWRNORM;
 }