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Windows-Specific Options
-------------------------
--allow-nonadmin TAP-adapter
(Standalone) Set ``TAP-adapter`` to allow access from non-administrative
accounts. If ``TAP-adapter`` is omitted, all TAP adapters on the system
will be configured to allow non-admin access. The non-admin access
setting will only persist for the length of time that the TAP-Win32
device object and driver remain loaded, and will need to be re-enabled
after a reboot, or if the driver is unloaded and reloaded. This
directive can only be used by an administrator.
--block-outside-dns
Block DNS servers on other network adapters to prevent DNS leaks. This
option prevents any application from accessing TCP or UDP port 53 except
one inside the tunnel. It uses Windows Filtering Platform (WFP) and
works on Windows Vista or later.
This option is considered unknown on non-Windows platforms and
unsupported on Windows XP, resulting in fatal error. You may want to use
``--setenv opt`` or ``--ignore-unknown-option`` (not suitable for
Windows XP) to ignore said error. Note that pushing unknown options from
server does not trigger fatal errors.
--cryptoapicert select-string
*(Windows/OpenSSL Only)* Load the certificate and private key from the
Windows Certificate System Store.
Use this option instead of ``--cert`` and ``--key``.
This makes it possible to use any smart card, supported by Windows, but
also any kind of certificate, residing in the Cert Store, where you have
access to the private key. This option has been tested with a couple of
different smart cards (GemSAFE, Cryptoflex, and Swedish Post Office eID)
on the client side, and also an imported PKCS12 software certificate on
the server side.
To select a certificate, based on a substring search in the
certificate's subject:
::
cryptoapicert "SUBJ:Peter Runestig"
To select a certificate, based on certificate's thumbprint:
::
cryptoapicert "THUMB:f6 49 24 41 01 b4 ..."
The thumbprint hex string can easily be copy-and-pasted from the Windows
Certificate Store GUI.
--dhcp-release
Ask Windows to release the TAP adapter lease on shutdown. This option
has no effect now, as it is enabled by default starting with
OpenVPN 2.4.1.
--dhcp-renew
Ask Windows to renew the TAP adapter lease on startup. This option is
normally unnecessary, as Windows automatically triggers a DHCP
renegotiation on the TAP adapter when it comes up, however if you set
the TAP-Win32 adapter Media Status property to "Always Connected", you
may need this flag.
--ip-win32 method
When using ``--ifconfig`` on Windows, set the TAP-Win32 adapter IP
address and netmask using ``method``. Don't use this option unless you
are also using ``--ifconfig``.
:code:`manual`
Don't set the IP address or netmask automatically. Instead
output a message to the console telling the user to configure the
adapter manually and indicating the IP/netmask which OpenVPN
expects the adapter to be set to.
:code:`dynamic [offset] [lease-time]`
Automatically set the IP address and netmask by replying to DHCP
query messages generated by the kernel. This mode is probably the
"cleanest" solution for setting the TCP/IP properties since it
uses the well-known DHCP protocol. There are, however, two
prerequisites for using this mode:
(1) The TCP/IP properties for the TAP-Win32 adapter must be set
to "Obtain an IP address automatically", and
(2) OpenVPN needs to claim an IP address in the subnet for use
as the virtual DHCP server address.
By default in ``--dev tap`` mode, OpenVPN will take the normally
unused first address in the subnet. For example, if your subnet is
:code:`192.168.4.0 netmask 255.255.255.0`, then OpenVPN will take
the IP address :code:`192.168.4.0` to use as the virtual DHCP
server address. In ``--dev tun`` mode, OpenVPN will cause the DHCP
server to masquerade as if it were coming from the remote endpoint.
The optional offset parameter is an integer which is > :code:`-256`
and < :code:`256` and which defaults to -1. If offset is positive,
the DHCP server will masquerade as the IP address at network
address + offset. If offset is negative, the DHCP server will
masquerade as the IP address at broadcast address + offset.
The Windows :code:`ipconfig /all` command can be used to show what
Windows thinks the DHCP server address is. OpenVPN will "claim"
this address, so make sure to use a free address. Having said that,
different OpenVPN instantiations, including different ends of
the same connection, can share the same virtual DHCP server
address.
The ``lease-time`` parameter controls the lease time of the DHCP
assignment given to the TAP-Win32 adapter, and is denoted in
seconds. Normally a very long lease time is preferred because it
prevents routes involving the TAP-Win32 adapter from being lost
when the system goes to sleep. The default lease time is one year.
:code:`netsh`
Automatically set the IP address and netmask using the Windows
command-line "netsh" command. This method appears to work correctly
on Windows XP but not Windows 2000.
:code:`ipapi`
Automatically set the IP address and netmask using the Windows IP
Helper API. This approach does not have ideal semantics, though
testing has indicated that it works okay in practice. If you use
this option, it is best to leave the TCP/IP properties for the
TAP-Win32 adapter in their default state, i.e. "Obtain an IP
address automatically."
:code:`adaptive` (Default)
Try :code:`dynamic` method initially and fail over to :code:`netsh`
if the DHCP negotiation with the TAP-Win32 adapter does not succeed
in 20 seconds. Such failures have been known to occur when certain
third-party firewall packages installed on the client machine block
the DHCP negotiation used by the TAP-Win32 adapter. Note that if
the :code:`netsh` failover occurs, the TAP-Win32 adapter TCP/IP
properties will be reset from DHCP to static, and this will cause
future OpenVPN startups using the :code:`adaptive` mode to use
:code:`netsh` immediately, rather than trying :code:`dynamic` first.
To "unstick" the :code:`adaptive` mode from using :code:`netsh`,
run OpenVPN at least once using the :code:`dynamic` mode to restore
the TAP-Win32 adapter TCP/IP properties to a DHCP configuration.
--pause-exit
Put up a "press any key to continue" message on the console prior to
OpenVPN program exit. This option is automatically used by the Windows
explorer when OpenVPN is run on a configuration file using the
right-click explorer menu.
--register-dns
Run :code:`ipconfig /flushdns` and :code:`ipconfig /registerdns` on
connection initiation. This is known to kick Windows into recognizing
pushed DNS servers.
--route-method m
Which method ``m`` to use for adding routes on Windows?
:code:`adaptive` (default)
Try IP helper API first. If that fails, fall back to the route.exe
shell command.
:code:`ipapi`
Use IP helper API.
:code:`exe`
Call the route.exe shell command.
--service args
Should be used when OpenVPN is being automatically executed by another
program in such a context that no interaction with the user via display
or keyboard is possible.
Valid syntax:
::
service exit-event [0|1]
In general, end-users should never need to explicitly use this option,
as it is automatically added by the OpenVPN service wrapper when a given
OpenVPN configuration is being run as a service.
``exit-event`` is the name of a Windows global event object, and OpenVPN
will continuously monitor the state of this event object and exit when
it becomes signaled.
The second parameter indicates the initial state of ``exit-event`` and
normally defaults to 0.
Multiple OpenVPN processes can be simultaneously executed with the same
``exit-event`` parameter. In any case, the controlling process can
signal ``exit-event``, causing all such OpenVPN processes to exit.
When executing an OpenVPN process using the ``--service`` directive,
OpenVPN will probably not have a console window to output status/error
messages, therefore it is useful to use ``--log`` or ``--log-append`` to
write these messages to a file.
--show-adapters
(Standalone) Show available TAP-Win32 adapters which can be selected
using the ``--dev-node`` option. On non-Windows systems, the
``ifconfig``\(8) command provides similar functionality.
--show-net
(Standalone) Show OpenVPN's view of the system routing table and network
adapter list.
--show-net-up
Output OpenVPN's view of the system routing table and network adapter
list to the syslog or log file after the TUN/TAP adapter has been
brought up and any routes have been added.
--show-valid-subnets
(Standalone) Show valid subnets for ``--dev tun`` emulation. Since the
TAP-Win32 driver exports an ethernet interface to Windows, and since TUN
devices are point-to-point in nature, it is necessary for the TAP-Win32
driver to impose certain constraints on TUN endpoint address selection.
Namely, the point-to-point endpoints used in TUN device emulation must
be the middle two addresses of a /30 subnet (netmask 255.255.255.252).
--tap-sleep n
Cause OpenVPN to sleep for ``n`` seconds immediately after the TAP-Win32
adapter state is set to "connected".
This option is intended to be used to troubleshoot problems with the
``--ifconfig`` and ``--ip-win32`` options, and is used to give the
TAP-Win32 adapter time to come up before Windows IP Helper API
operations are applied to it.
--win-sys path
Set the Windows system directory pathname to use when looking for system
executables such as ``route.exe`` and ``netsh.exe``. By default, if this
directive is not specified, OpenVPN will use the SystemRoot environment
variable.
This option has changed behaviour since OpenVPN 2.3. Earlier you had to
define ``--win-sys env`` to use the SystemRoot environment variable,
otherwise it defaulted to :code:`C:\\WINDOWS`. It is not needed to use
the ``env`` keyword any more, and it will just be ignored. A warning is
logged when this is found in the configuration file.
--windows-driver drv
Specifies which tun driver to use. Values are :code:`tap-windows6`
(default) and :code:`wintun`. This is a Windows-only option.
:code:`wintun`" requires ``--dev tun`` and the OpenVPN process to run
elevated, or be invoked using the Interactive Service.
|
