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``. A more limited version also works in client-to-server and server-to-client scenarios where one of the end points uses a v2.4 client or server and the other side uses an older version. In such scenarios the v2.4 side will change to the ``--cipher`` set by the remote side, if permitted by by ``--ncp-ciphers``. For example, a v2.4 client with ``--cipher BF-CBC`` and ``ncp-ciphers AES-256-GCM:AES-256-CBC`` can connect to both a v2.3 server with ``cipher BF-CBC`` as well as a server with ``cipher AES-256-CBC`` in its config. The other way around, a v2.3 client with either ``cipher BF-CBC`` or ``cipher AES-256-CBC`` can connect to a v2.4 server with e.g. ``cipher BF-CBC`` and ``ncp-ciphers AES-256-GCM:AES-256-CBC`` in its config. For this to work it requires that OpenVPN was built without disabling OCC support. 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. Support for providing IPv6 DNS servers A new DHCP sub-options ``DNS6`` is added alongside with the already existing ``DNS`` sub-option. This is used to provide DNS resolvers available over IPv6. This will be pushed to clients and `` --up`` scripts and ``--plugin`` can act upon it through the ``foreign_option_`` environment variables. Support for the Windows client picking up this new sub-option is added, however IPv6 DNS resolvers needs to be configured via ``netsh`` which requires administrator privileges if the new interactive services on Windows is not being used. If the interactive services is used, this service will execute ``netsh`` in the background with the proper privileges. 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 if no flags are given, and the interactive service is used, "def1" is implicitly set (because "delete and later reinstall the existing default route" does not work well here). If not using the service, the old behaviour is kept. 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 ```` .. ```` Windows version Windows version is detected, logged and possibly signalled to server (IV_PLAT_VER= 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. Control channel encryption (``--tls-crypt``) Use a pre-shared static key (like the ``--tls-auth`` key) to encrypt control channel packets. Provides more privacy, some obfuscation and poor-man's post-quantum security. Asynchronous push reply If asynchronous authentication is enabled and completed after server received PUSH_REQUEST message, server sends PUSH_REPLY immediately without waiting for next PUSH_REQUEST. Requires use of ``--enable-async-push`` as ./configure parameter at build time. Deprecated features ------------------- - ``--key-method 1`` is deprecated in 2.4 and will be removed in 2.5. Migrate away from ``--key-method 1`` as soon as possible. The recommended approach is to remove the ``--key-method`` option from the configuration files, OpenVPN will then use ``--key-method 2`` by default. Note that this requires changing the option in both the client and server side configs. - CRLs are now handled by the crypto library (OpenSSL or mbed TLS), instead of inside OpenVPN itself. The crypto library implementations are more strict than the OpenVPN implementation was. This might reject peer certificates that would previously be accepted. If this occurs, OpenVPN will log the crypto library's error description. - ``--tls-remote`` is removed in 2.4, as indicated in the 2.3 man-pages. A similar functionality is provided via ``--verify-x509-name`` which does the same job in a better way. - ``--compat-names`` and ``--no-name-remapping`` was deprecated in 2.3 and will be removed in 2.5. All scripts and plug-ins depending on the old non-standard X.509 subject formatting must be updated to the standardized formatting. See the man page for more information. - ``--no-iv`` is deprecated in 2.4 and will be remove in 2.5. 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). - On the client side recursively routed packets, which have same destination as the VPN server, are dropped. This could be disabled with --allow-recursive-routing option. - on Windows, when the ``--register-dns`` option is set, OpenVPN no longer restarts the ``dnscache`` service - this had unwanted side effects, and seems to be no longer necessary with currently supported Windows versions. - OpenVPN now reloads a CRL only if the modication time or file size has changed, instead of for each new connection. This reduces the connection setup time, in particular when using large CRLs. - OpenVPN now ships with more up-to-date systemd unit files which takes advantage of the improved service management as well as some hardening steps. The configuration files are picked up from /etc/openvpn/server and /etc/openvpn/client (depending on unit file). This also avoids these new unit files and how they work to collide with older pre-existing unit files. - using ``--no-iv`` (which is generally not a recommended setup) will require explicitly disabling NCP with ``--disable-ncp``. This is intentional because NCP will by default use AES-GCM, which requires an IV - so we want users of that option to consciously reconsider. 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. - Linux distributions using systemd is highly encouraged to ship these new unit files instead of older ones, to provide a unified behaviour across systemd based Linux distributions.