man: Clarify IV_HWADDR

The IV_HWADDR description was only partially correct, as there are more
implementations using other values than the MAC address of the default
gateway.

The intention of this value is to provide a unique identifier of the
client and on some platforms this is not possible to retrieve other than
to generate this information.

The 64 bytes limitation is an arbitrary value, it is not enforced by
OpenVPN 2.x.  But it was considered a good idea to at least have some
reasonable upper limit of how long this string can be, at least for
those implementing support for this information.

Signed-off-by: David Sommerseth <davids@openvpn.net>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20210709134849.161728-1-openvpn@sf.lists.topphemmelig.net>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg22625.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 51d85a9d287f44c373eaa514c6a52e1078c27c43)

diff --git a/doc/man-sections/server-options.rst b/doc/man-sections/server-options.rst
index 98a1641bd318d2680399c548c038cc425d3ea04f..ac0df558581f778fc77b3c82c035b69cda9af513 100644 (file)
--- a/doc/man-sections/server-options.rst
+++ b/doc/man-sections/server-options.rst
@@ -494,8 +494,14 @@ fast hardware. SSL/TLS authentication must be used in this mode.
   When ``--push-peer-info`` is enabled the additional information consists
   of the following data:
 
-  :code:`IV_HWADDR=<mac address>`
-        The MAC address of clients default gateway
+  :code:`IV_HWADDR=<string>`
+        This is intended to be a unique and persistent ID of the client.
+        The string value can be any readable ASCII string up to 64 bytes.
+        OpenVPN 2.x and some other implementations use the MAC address of
+        the client's interface used to reach the default gateway. If this
+        string is generated by the client, it should be consistent and
+        preserved across independent session and preferably
+        re-installations and upgrades.
 
   :code:`IV_SSL=<version string>`
         The ssl version used by the client, e.g.