diff --git a/docs/udp_tracker_protocol.html b/docs/udp_tracker_protocol.html
index 635b48f27..12057aa76 100644
--- a/docs/udp_tracker_protocol.html
+++ b/docs/udp_tracker_protocol.html
@@ -52,6 +52,37 @@ retrying.</p>
 </tr>
 </tbody>
 </table>
+<p>optional part</p>
+<table border class="table">
+<colgroup>
+<col width="18%" />
+<col width="28%" />
+<col width="54%" />
+</colgroup>
+<thead valign="bottom">
+<tr><th>size</th>
+<th>name</th>
+<th>description</th>
+</tr>
+</thead>
+<tbody valign="top">
+<tr><td>int8_t</td>
+<td>flags</td>
+<td>1 = authentication</td>
+</tr>
+<tr><td>int8_t[8]</td>
+<td>username</td>
+<td>&nbsp;</td>
+</tr>
+<tr><td>int8_t[8]</td>
+<td>password_hash</td>
+<td>sha1-hash of the tracker password</td>
+</tr>
+</tbody>
+</table>
+<p>what is the point of having a fixed size username field instead of
+a null-terminated string?</p>
+<p>Why send the hash of the password instead of the password itself?</p>
 <p>Server replies with packet:</p>
 <table border class="table">
 <colgroup>
diff --git a/docs/udp_tracker_protocol.rst b/docs/udp_tracker_protocol.rst
index c9109d564..3f4e424d4 100755
--- a/docs/udp_tracker_protocol.rst
+++ b/docs/udp_tracker_protocol.rst
@@ -40,6 +40,24 @@ Client sends packet:
 | int32_t     | transaction_id      | Randomized by client.                  |
 +-------------+---------------------+----------------------------------------+
 
+optional part
+
++-------------+---------------------+----------------------------------------+
+| size        | name                | description                            |
++=============+=====================+========================================+
+| int8_t      | flags               | 1 = authentication                     |
++-------------+---------------------+----------------------------------------+
+| int8_t[8]   | username            |                                        |
++-------------+---------------------+----------------------------------------+
+| int8_t[8]   | password_hash       | sha1-hash of the tracker password      |
++-------------+---------------------+----------------------------------------+
+
+what is the point of having a fixed size username field instead of
+a null-terminated string?
+
+Why send the hash of the password instead of the password itself?
+
+
 Server replies with packet:
 
 +-------------+---------------------+----------------------------------------+
diff --git a/src/file.cpp b/src/file.cpp
index 3551057dd..2f500f0e5 100755
--- a/src/file.cpp
+++ b/src/file.cpp
@@ -38,12 +38,17 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #include <io.h>
 #include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+typedef int mode_t;
 
 #else
 
 #define _FILE_OFFSET_BITS 64
 #include <unistd.h>
 #include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 
 #endif
 
@@ -57,9 +62,9 @@ namespace
 {
 	enum { mode_in = 1, mode_out = 2 };
 
-	int map_open_mode(int m)
+	mode_t map_open_mode(int m)
 	{
-		if (m == (mode_in | mode_out)) return O_RDWR | O_BINARY;
+//		if (m == (mode_in | mode_out)) return O_RDWR | O_BINARY;
 		if (m == mode_out) return O_WRONLY | O_CREAT | O_BINARY;
 		if (m == mode_in) return O_RDONLY | O_BINARY;
 		assert(false);
@@ -97,8 +102,10 @@ namespace libtorrent
 		void open(fs::path const& path, int mode)
 		{
 			close();
-			m_fd = ::open(path.native_file_string().c_str(), map_open_mode(mode));
-			m_open_mode = mode;
+			m_fd = ::open(
+				path.native_file_string().c_str()
+				, map_open_mode(mode)
+				, S_IREAD | S_IWRITE);
 			if (m_fd == -1)
 			{
 				std::stringstream msg;
@@ -106,6 +113,7 @@ namespace libtorrent
 					<< strerror(errno);
 				throw file_error(msg.str());
 			}
+			m_open_mode = mode;
 		}
 
 		void close()