Version 2.4.0
=============
New features
------------
Peer ID support
Added new packet format P_DATA_V2, which includes peer-id. If
server and client support it, client sends all data packets in
the new format. When data packet arrives, server identifies peer
by peer-id. If peer's ip/port has changed, server assumes that
client has floated, verifies HMAC and updates ip/port in internal structs.
Cipher negotiation
Data channel ciphers are now by default negotiated. If a client advertises
support for Negotiable Crypto Parameters (NCP), the server will choose a
cipher (by default AES-256-GCM) for the data channel, and tell the client
to use that cipher. Data channel cipher negotiation can be controlled
using ``--ncp-ciphers`` and ``--ncp-disable``.
AEAD (GCM) data channel cipher support
The data channel now supports AEAD ciphers (currently only GCM). The AEAD
packet format has a smaller overhead than the CBC packet format, (e.g. 20
bytes per packet for AES-128-GCM instead of 36 bytes per packet for
AES-128-CBC + HMAC-SHA1).
ECDH key exchange
The TLS control channel now supports for elliptic curve diffie-hellmann
key exchange (ECDH).
Dualstack client connect
Instead of only using the first address of each ``--remote`` OpenVPN
will now try all addresses (IPv6 and IPv4) of a ``--remote`` entry.
New improved Windows Background service
The new OpenVPNService is based on openvpnserv2, a complete rewrite of the OpenVPN
service wrapper. It is intended for launching OpenVPN instances that should be
up at all times, instead of being manually launched by a user. OpenVPNService is
able to restart individual OpenVPN processes if they crash, and it also works
properly on recent Windows versions. OpenVPNServiceLegacy tends to work poorly,
if at all, on newer Windows versions (8+) and its use is not recommended.
New interactive Windows service
The installer starts OpenVPNServiceInteractive automatically and configures
it to start at system startup.
The interactive Windows service allows unprivileged users to start
OpenVPN connections in the global config directory (usually
C:\Program Files\OpenVPN\config) using OpenVPN GUI without any
extra configuration.
Users who belong to the built-in Administrator group or to the
local "OpenVPN Administrator" group can also store configuration
files under %USERPROFILE%\OpenVPN\config for use with the
interactive service.
redirect-gateway ipv6
OpenVPN has now feature parity between IPv4 and IPv6 for redirect
gateway including the handling of overlapping IPv6 routes with
IPv6 remote VPN server address
LZ4 Compression and pushable compression
Additionally to LZO compression OpenVPN now also supports LZ4 compression.
Compression options are now pushable from the server.
pull-filter
New option to explicitly allow or reject options pushed by the server.
May be used multiple times and is applied in the order specified.
push-remove
new option to remove options on a per-client basis from the "push" list
(more fine-grained than ``--push-reset``)
Http proxy password inside config file
Http proxy passwords can be specified with the inline file option
``<http-proxy-user-pass>`` .. ``</http-proxy-user-pass>``
Windows version
Windows version is detected, logged and possibly signalled to server
(IV_PLAT_VER=<nn> if ``--push-peer-info`` is set on client)
Authentication tokens
In situations where it is not suitable to save users passwords on the client
OpenVPN have since v2.3 had support for --auth-token. This option is
pushed from the server to the client with a token value to be used instead
of the users password. For this to work, the authentication plug-in would
need to implement this support as well. In OpenVPN 2.4 --auth-gen-token
is introduced, which will allow the OpenVPN server to generate a random
token and push it to the client without any changes to the authentication
modules. When the clients need to re-authenticate the OpenVPN server will
instead of sending the re-authentication request to the authentication
module do the authentication internally. This feature is especially
useful in configurations which adds One Time Password (OTP) authentication
schemes, as this allows the tunnel to be renegotiated regularly without
any need to supply new OTP codes.
keying-material-exporter
Keying Material Exporter [RFC-5705] allow additional keying material to be
derived from existing TLS channel.
Mac OS X Keychain management client
added contrib/keychain-mcd which allows to use Mac OS X keychain
certificates with OpenVPN
Android platform support
Support for running on Android using Android's VPNService API has been added.
See doc/android.txt for more details. This support is primarily used in
the OpenVPN for Android app (https://github.com/schwabe/ics-openvpn)
AIX platform support
AIX platform support has been added. The support only includes tap
devices since AIX does not provide tun interface.
User-visible Changes
--------------------
- For certificate DNs with duplicate fields, e.g. "OU=one,OU=two", both fields
are now exported to the environment, where each second and later occurrence
of a field get _$N appended to it's field name, starting at N=1. For the
example above, that would result in e.g. X509_0_OU=one, X509_0_OU_1=two.
Note that this breaks setups that rely on the fact that OpenVPN would
previously (incorrectly) only export the last occurence of a field.
- proto udp and proto tcp specify to use IPv4 and IPv6. The new
options proto udp4 and tcp4 specify to use IPv4 only.
- ``--sndbuf`` and ``--recvbuf`` default now to OS defaults instead of 64k
- OpenVPN exits with an error if an option has extra parameters;
previously they were silently ignored
- The default of ``--tls-cipher`` is now "DEFAULT:!EXP:!PSK:!SRP:!kRSA"
instead of "DEFAULT" to always select perfect forward security
cipher suites
- ``--tls-auth`` always requires OpenVPN static key files and will no
longer work with free form files
- ``--proto udp6/tcp6`` in server mode will now try to always listen to
both IPv4 and IPv6 on platforms that allow it. Use ``--bind ipv6only``
to explicitly listen only on IPv6.
- Removed ``--enable-password-save`` from configure. This option is now
always enabled.
- Stricter default TLS cipher list (override with ``--tls-cipher``), that now
also disables:
* Non-ephemeral key exchange using static (EC)DH keys
* DSS private keys
- mbed TLS builds: changed the tls_digest_N values exported to the script
environment to be equal to the ones exported by OpenSSL builds, namely
the certificate fingerprint (was the hash of the 'to be signed' data).
- mbed TLS builds: minimum RSA key size is now 2048 bits. Shorter keys will
not be accepted, both local and from the peer.
- ``--connect-timeout`` specifies now the timeout until the first TLS packet
is received (identical to ``--server-poll-timeout``) and this timeout now
includes the removed socks proxy timeout and http proxy timeout.
In ``--static`` mode connect-timeout specifies the timeout for TCP and
proxy connection establishment
- ``--connect-retry-max`` now specifies the maximum number of unsuccessful
attempts of each remote/connection entry before exiting.
- ``--http-proxy-timeout`` and the static non-changeable socks timeout (5s)
have been folded into a "unified" ``--connect-timeout`` which covers all
steps needed to connect to the server, up to the start of the TLS exchange.
The default value has been raised to 120s, to handle slow http/socks
proxies graciously. The old "fail TCP fast" behaviour can be achieved by
adding "``--connect-timeout 10``" to the client config.
- ``--http-proxy-retry`` and ``--sock-proxy-retry`` have been removed. Proxy connections
will now behave like regular connection entries and generate a USR1 on failure.
- ``--connect-retry`` gets an optional second argument that specifies the maximum
time in seconds to wait between reconnection attempts when an exponential
backoff is triggered due to repeated retries. Default = 300 seconds.
- Data channel cipher negotiation (see New features section) can override
ciphers configured in the config file. Use ``--ncp-disable`` if you do not want
this behavior.
- All tun devices on all platforms are always considered to be IPv6
capable. The ``--tun-ipv6`` option is ignored (behaves like it is always
on).
Maintainer-visible changes
--------------------------
- OpenVPN no longer supports building with crypto support, but without TLS
support. As a consequence, OPENSSL_CRYPTO_{CFLAGS,LIBS} and
OPENSSL_SSL_{CFLAGS,LIBS} have been merged into OPENSSL_{CFLAGS,LIBS}. This
is particularly relevant for maintainers who build their own OpenSSL library,
e.g. when cross-compiling.