1Overview of changes in 2.5.6 2============================ 3 4User-visible Changes 5-------------------- 6- update copyright year to 2022 7 8New features 9------------ 10- new plugin (sample-plugin/defer/multi-auth.c) to help testing with 11 multiple parallel plugins that succeed/fail in direct/deferred mode 12 13- various build improvements (github actions etc) 14 15- upgrade pkcs11-helper to release 1.28.4 16 17Bugfixes 18-------- 19- CVE-2022-0547 20 see https://community.openvpn.net/openvpn/wiki/SecurityAnnouncements 21 22 If openvpn is configured with multiple authentication plugins and 23 more than one plugin tries to do deferred authentication, the result 24 is not well-defined - creating a possible authentication bypass. 25 26 In this situation the server process will now abort itself with a clear 27 log message. Only one plugin is allowed to do deferred authentication. 28 29- Fix "--mtu-disc maybe|yes" on Linux 30 31 Due to configure/syshead.h/#ifdef confusion, the code in question was 32 not compiled-in since a long time. Fixed. Trac: #1452 33 34- Fix $common_name variable passed to scripts when username-as-common-name 35 is in effect. 36 37 This was not consistently set - sometimes, OpenVPN exported the username, 38 sometimes the common name from the client cert. Fixed. Trac: #1434 39 40- Fix potential memory leaks in add_route() and add_route_ipv6(). 41 42- Apply connect-retry backoff only to one side of the connection in 43 p2p mode. Without that fix/enhancement, two sides could end up 44 only sending packets when the other end is not ready. Trac: #1010, #1384 45 46- remove unused sitnl.h file 47 48- clean up msvc build files, remove unused MSVC build .bat files 49 50- repair "--inactive" handling with a 'bytes' parameter larger than 2 Gbytes 51 52 due to integer overflow, this ended up being "0" on Linux, but on 53 Windows with MSVC it ends up being "always 2 Gbyte", both not doing 54 what is requested. Trac: #1448 55 56- repair handling of EC certificates on Windows with pkcs11-helper 57 58 (wrong compile-time defines for OpenSSL 1.1.1) 59 60Documentation 61------------- 62- documentation improvements related to DynDNS. Trac: #1417 63 64- clean up documentation for --proto and related options 65 66- rebuild rst docs if input files change (proper dependency handling) 67 68 69 70Overview of changes in 2.5.5 71============================ 72 73User-visible Changes 74-------------------- 75- SWEET32/64bit cipher deprecation change was postponed to 2.7 76 77- Windows: use network address for emulated DHCP server as default 78 this enables use of a /30 subnet, which is needed when connecting 79 to OpenVPN Cloud. 80 81- require EC support in windows builds 82 (this means it's no longer possible to build a Windows OpenVPN binary 83 with an OpenSSL lib without EC support) 84 85New features 86------------ 87- Windows build: use CFG and Spectre mitigations on MSVC builds 88 89- bring back OpenSSL config loading to Windows builds. 90 OpenSSL config is loaded from %installdir%\\ssl\\openssl.cnf 91 (typically: c:\\program files\\openvpn\\ssl\\openssl.cnf) if it exists. 92 93 This is important for some hardware tokens which need special 94 OpenSSL config for correct operation. Trac #1296 95 96Bugfixes 97-------- 98- Windows build: enable EKM 99 100- Windows build: improve various vcpkg related build issues 101 102- Windows build: fix regression related to non-writeable status files 103 (Trac #1430) 104 105- Windows build: fix regression that broke OpenSSL EC support 106 107- Windows build: fix "product version" display (2.5..4 -> 2.5.4) 108 109- Windows build: fix regression preventing use of PKCS12 files 110 111- improve "make check" to notice if "openvpn --show-cipher" crashes 112 113- improve argv unit tests 114 115- ensure unit tests work with mbedTLS builds without BF-CBC ciphers 116 117- include "--push-remove" in the output of "openvpn --help" 118 119- fix error in iptables syntax in example firewall.sh script 120 121- fix "resolvconf -p" invocation in example "up" script 122 123- fix "common_name" environment for script calls when 124 "--username-as-common-name" is in effect (Trac #1434) 125 126Documentation 127------------- 128- move "push-peer-info" documentation from "server options" to "client" 129 (where it belongs) 130 131- correct "foreign_option_{n}" typo in manpage 132 133- update IRC information in CONTRIBUTING.rst (libera.chat) 134 135- README.down-root: fix plugin module name 136 137 138Overview of changes in 2.5.4 139============================ 140Bugfixes 141-------- 142- fix prompting for password on windows console if stderr redirection 143 is in use - this breaks 2.5.x on Win11/ARM, and might also break 144 on Win11/adm64 when released. 145 146- fix setting MAC address on TAP adapters (--lladdr) to use sitnl 147 (was overlooked, and still used "ifconfig" calls) 148 149- various improvements for man page building (rst2man/rst2html etc) 150 151- minor bugfix with IN6_IS_ADDR_UNSPECIFIED() use (breaks build on 152 at least one platform strictly checking this) 153 154- fix minor memory leak under certain conditions in add_route() and 155 add_route_ipv6() 156 157User-visible Changes 158-------------------- 159- documentation improvements 160 161- copyright updates where needed 162 163- better error reporting when win32 console access fails 164 165New features 166------------ 167- also build man page on Windows builds 168 169 170Overview of changes in 2.5.3 171============================ 172Bugfixes 173-------- 174- CVE-2021-3606 175 see https://community.openvpn.net/openvpn/wiki/SecurityAnnouncements 176 177 OpenVPN windows builds could possibly load OpenSSL Config files from 178 world writeable locations, thus posing a security risk to OpenVPN. 179 180 As a fix, disable OpenSSL config loading completely on Windows. 181 182- disable connect-retry backoff for p2p (--secret) instances 183 (Trac #1010, #1384) 184 185- fix build with mbedtls w/o SSL renegotiation support 186 187- Fix SIGSEGV (NULL deref) receiving push "echo" (Trac #1409) 188 189- MSI installers: properly schedule reboot in the end of installation 190 191- fix small memory leak in free_key_ctx for auth_token 192 193 194User-visible Changes 195-------------------- 196- update copyright messages in files and --version output 197 198New features 199------------ 200- add --auth-token-user option (for --auth-token deployments without 201 --auth-user-pass in client config) 202 203- improve MSVC building for Windows 204 205- official MSI installers will now contain arm64 drivers and binaries 206 (x86, amd64, arm64) 207 208 209Overview of changes in 2.5.2 210============================ 211 212Bugfixes 213-------- 214- CVE-2020-15078 215 see https://community.openvpn.net/openvpn/wiki/SecurityAnnouncements 216 217 This bug allows - under very specific circumstances - to trick a 218 server using delayed authentication (plugin or management) into 219 returning a PUSH_REPLY before the AUTH_FAILED message, which can 220 possibly be used to gather information about a VPN setup. 221 222 In combination with "--auth-gen-token" or an user-specific token auth 223 solution it can be possible to get access to a VPN with an 224 otherwise-invalid account. 225 226- restore pushed "ping" settings correctly on a SIGUSR1 restart 227 228- avoid generating unecessary mbed debug messages - this is actually 229 a workaround for an mbedTLS 2.25 bug when using Curve25519 and Curve448 230 ED curves - mbedTLS crashes on preparing debug infos that we do not 231 actually need unless running with "--verb 8" 232 233- do not print inlined (<dh>...</dh>) Diffie Hellman parameters to log file 234 235- fix Linux/SITNL default route lookup in case of multiple routing tables 236 with more than one default route present (always use "main table" for now) 237 238- Fix CRL file handling in combination with chroot 239 240User-visible Changes 241-------------------- 242 243- OpenVPN will now refuse to start if CRL file is not present at startup 244 time. At "reload time" absense of the CRL file is still OK (and the 245 in memory copy is used) but at startup it is now considered an error. 246 247 248New features 249------------ 250- printing of the TLS ciphers negotiated has been extended, especially 251 displaying TLS 1.3 and EC certificates more correctly. 252 253 254Overview of changes in 2.5.1 255============================ 256 257New features 258------------ 259- "echo msg" support, to enable the server to pushed messages that are 260 then displayed by the client-side GUI. See doc/gui-notes.txt and 261 doc/management-notes.txt. 262 263 Supported by the Windows GUI shipped in 2.5.1, not yet supported by 264 Tunnelblick and the Android GUI. 265 266User-visible Changes 267-------------------- 268- make OPENVPN_PLUGIN_ENABLE_PF plugin failures FATAL - if a plugin offers 269 to set the "openvpn packet filter", and returns a failure when requested 270 to, OpenVPN 2.5.0 would crash trying to clean up not-yet-initialized 271 structure members. Since PF is going away in 2.6.0, this is just turning 272 the crash into a well-defined program abort, and no further effort has 273 been spent in rewriting the PF plugin error handling (see trac #1377). 274 275Documentation 276------------- 277- rework sample-plugins/defer/simple.c - this is an extensive rewrite 278 of the plugin to bring code quality to acceptable standards and add 279 documentation on the various plugin API aspects. Since it's just 280 example code, filed under "Documentation", not under "Bugfix". 281 282- various man page improvements. 283 284- clarify ``--block-ipv6`` intent and direction 285 286Bugfixes 287-------- 288- fix installation of openvpn.8 manpage on systems without docutils. 289 290- Windows: fix DNS search list setup for domains with "-" chars. 291 292- Fix tls-auth mismatch OCC message when tls-cryptv2 is used. 293 294- Windows: Skip DHCP renew with Wintun adapter (Wintun does not support 295 DHCP, so this was just causing an - harmless - error and needless delay). 296 297- Windows: Remove 1 second delay before running netsh - speeds up 298 interface init for wintun setups not using the interactive service. 299 300- Windows: Fix too early argv freeing when registering DNS - this would 301 cause a client side crash on Windows if ``register-dns`` is used, 302 and the interactive service is not used. 303 304- Android: Zero initialise msghdr prior to calling sendmesg. 305 306- Fix line number reporting on config file errors after <inline> segments 307 (see Trac #1325). 308 309- Fix port-share option with TLS-Crypt v2. 310 311- tls-crypt-v2: also preload tls-crypt-v2 keys (if --persist-key), otherwise 312 dropping privs on the server would fail. 313 314- tls-crypt-v2: fix server memory leak (about 600 bytes per connecting 315 client with tls-crypt-v2) 316 317- rework handling of server-pushed ``--auth-token`` in combination with 318 ``--auth-nocache`` on reconnection / TLS renegotiation events. This 319 used to "forget" to update new incoming token after a reconnection event 320 (leading to failure to reauth some time later) and now works in all 321 tested cases. 322 323 324Overview of changes in 2.5.0 325============================ 326 327New features 328------------ 329Client-specific tls-crypt keys (``--tls-crypt-v2``) 330 ``tls-crypt-v2`` adds the ability to supply each client with a unique 331 tls-crypt key. This allows large organisations and VPN providers to profit 332 from the same DoS and TLS stack protection that small deployments can 333 already achieve using ``tls-auth`` or ``tls-crypt``. 334 335ChaCha20-Poly1305 cipher support 336 Added support for using the ChaCha20-Poly1305 cipher in the OpenVPN data 337 channel. 338 339Improved Data channel cipher negotiation 340 The option ``ncp-ciphers`` has been renamed to ``data-ciphers``. 341 The old name is still accepted. The change in name signals that 342 ``data-ciphers`` is the preferred way to configure data channel 343 ciphers and the data prefix is chosen to avoid the ambiguity that 344 exists with ``--cipher`` for the data cipher and ``tls-cipher`` 345 for the TLS ciphers. 346 347 OpenVPN clients will now signal all supported ciphers from the 348 ``data-ciphers`` option to the server via ``IV_CIPHERS``. OpenVPN 349 servers will select the first common cipher from the ``data-ciphers`` 350 list instead of blindly pushing the first cipher of the list. This 351 allows to use a configuration like 352 ``data-ciphers ChaCha20-Poly1305:AES-256-GCM`` on the server that 353 prefers ChaCha20-Poly1305 but uses it only if the client supports it. 354 355 See the data channel negotiation section in the manual for more details. 356 357Removal of BF-CBC support in default configuration: 358 By default OpenVPN 2.5 will only accept AES-256-GCM and AES-128-GCM as 359 data ciphers. OpenVPN 2.4 allows AES-256-GCM,AES-128-GCM and BF-CBC when 360 no --cipher and --ncp-ciphers options are present. Accepting BF-CBC can be 361 enabled by adding 362 363 data-ciphers AES-256-GCM:AES-128-GCM:BF-CBC 364 365 and when you need to support very old peers also 366 367 data-ciphers-fallback BF-CBC 368 369 To offer backwards compatibility with older configs an *explicit* 370 371 cipher BF-CBC 372 373 in the configuration will be automatically translated into adding BF-CBC 374 to the data-ciphers option and setting data-ciphers-fallback to BF-CBC 375 (as in the example commands above). We strongly recommend to switching 376 away from BF-CBC to a more secure cipher. 377 378Asynchronous (deferred) authentication support for auth-pam plugin. 379 See src/plugins/auth-pam/README.auth-pam for details. 380 381Deferred client-connect 382 The ``--client-connect`` option and the connect plugin API allow 383 asynchronous/deferred return of the configuration file in the same way 384 as the auth-plugin. 385 386Faster connection setup 387 A client will signal in the ``IV_PROTO`` variable that it is in pull 388 mode. This allows the server to push the configuration options to 389 the client without waiting for a ``PULL_REQUEST`` message. The feature 390 is automatically enabled if both client and server support it and 391 significantly reduces the connection setup time by avoiding one 392 extra packet round-trip and 1s of internal event delays. 393 394Netlink support 395 On Linux, if configured without ``--enable-iproute2``, configuring IP 396 addresses and adding/removing routes is now done via the netlink(3) 397 kernel interface. This is much faster than calling ``ifconfig`` or 398 ``route`` and also enables OpenVPN to run with less privileges. 399 400 If configured with --enable-iproute2, the ``ip`` command is used 401 (as in 2.4). Support for ``ifconfig`` and ``route`` is gone. 402 403Wintun support 404 On Windows, OpenVPN can now use ``wintun`` devices. They are faster 405 than the traditional ``tap9`` tun/tap devices, but do not provide 406 ``--dev tap`` mode - so the official installers contain both. To use 407 a wintun device, add ``--windows-driver wintun`` to your config 408 (and use of the interactive service is required as wintun needs 409 SYSTEM privileges to enable access). 410 411IPv6-only operation 412 It is now possible to have only IPv6 addresses inside the VPN tunnel, 413 and IPv6-only address pools (2.4 always required IPv4 config/pools 414 and IPv6 was the "optional extra"). 415 416Improved Windows 10 detection 417 Correctly log OS on Windows 10 now. 418 419Linux VRF support 420 Using the new ``--bind-dev`` option, the OpenVPN outside socket can 421 now be put into a Linux VRF. See the "Virtual Routing and Forwarding" 422 documentation in the man page. 423 424TLS 1.3 support 425 TLS 1.3 support has been added to OpenVPN. Currently, this requires 426 OpenSSL 1.1.1+. 427 The options ``--tls-ciphersuites`` and ``--tls-groups`` have been 428 added to fine tune TLS protocol options. Most of the improvements 429 were also backported to OpenVPN 2.4 as part of the maintainance 430 releases. 431 432Support setting DHCP search domain 433 A new option ``--dhcp-option DOMAIN-SEARCH my.example.com`` has been 434 defined, and Windows support for it is implemented (tun/tap only, no 435 wintun support yet). Other platforms need to support this via ``--up`` 436 script (Linux) or GUI (OSX/Tunnelblick). 437 438per-client changing of ``--data-ciphers`` or ``data-ciphers-fallback`` 439 from client-connect script/dir (NOTE: this only changes preference of 440 ciphers for NCP, but can not override what the client announces as 441 "willing to accept") 442 443Handle setting of tun/tap interface MTU on Windows 444 If IPv6 is in use, MTU must be >= 1280 (Windows enforces IETF requirements) 445 446Add support for OpenSSL engines to access private key material (like TPM). 447 448HMAC based auth-token support 449 The ``--auth-gen-token`` support has been improved and now generates HMAC 450 based user token. If the optional ``--auth-gen-token-secret`` option is 451 used clients will be able to seamlessly reconnect to a different server 452 using the same secret file or to the same server after a server restart. 453 454Improved support for pending authentication 455 The protocol has been enhanced to be able to signal that 456 the authentication should use a secondary authentication 457 via web (like SAML) or a two factor authentication without 458 disconnecting the OpenVPN session with AUTH_FAILED. The 459 session will instead be stay in a authenticated state and 460 wait for the second factor authentication to complete. 461 462 This feature currently requires usage of the managent interface 463 on both client and server side. See the `management-notes.txt` 464 ``client-pending-auth`` and ``cr-response`` commands for more 465 details. 466 467VLAN support 468 OpenVPN servers in TAP mode can now use 802.1q tagged VLANs 469 on the TAP interface to separate clients into different groups 470 that can then be handled differently (different subnets / DHCP, 471 firewall zones, ...) further down the network. See the new 472 options ``--vlan-tagging``, ``--vlan-accept``, ``--vlan-pvid``. 473 474 802.1q tagging on the client side TAP interface is not handled 475 today (= tags are just forwarded transparently to the server). 476 477Support building of .msi installers for Windows 478 479Allow unicode search string in ``--cryptoapicert`` option (Windows) 480 481Support IPv4 configs with /31 netmasks now 482 (By no longer trying to configure ``broadcast x.x.x.x'' in 483 ifconfig calls, /31 support "just works") 484 485New option ``--block-ipv6`` to reject all IPv6 packets (ICMPv6) 486 this is useful if the VPN service has no IPv6, but the clients 487 might have (LAN), to avoid client connections to IPv6-enabled 488 servers leaking "around" the IPv4-only VPN. 489 490``--ifconfig-ipv6`` and ``--ifconfig-ipv6-push`` will now accept 491 hostnames and do a DNS lookup to get the IPv6 address to use 492 493 494Deprecated features 495------------------- 496For an up-to-date list of all deprecated options, see this wiki page: 497https://community.openvpn.net/openvpn/wiki/DeprecatedOptions 498 499- ``ncp-disable`` has been deprecated 500 With the improved and matured data channel cipher negotiation, the use 501 of ``ncp-disable`` should not be necessary anymore. 502 503- ``inetd`` has been deprecated 504 This is a very limited and not-well-tested way to run OpenVPN, on TCP 505 and TAP mode only, which complicates the code quite a bit for little gain. 506 To be removed in OpenVPN 2.6 (unless users protest). 507 508- ``no-iv`` has been removed 509 This option was made into a NOOP option with OpenVPN 2.4. This has now 510 been completely removed. 511 512- ``--client-cert-not-required`` has been removed 513 This option will now cause server configurations to not start. Use 514 ``--verify-client-cert none`` instead. 515 516- ``--ifconfig-pool-linear`` has been removed 517 This option is removed. Use ``--topology p2p`` or ``--topology subnet`` 518 instead. 519 520- ``--compress xxx`` is considered risky and is warned against, see below. 521 522- ``--key-method 1`` has been removed 523 524 525User-visible Changes 526-------------------- 527- If multiple connect handlers are used (client-connect, ccd, connect 528 plugin) and one of the handler succeeds but a subsequent fails, the 529 client-disconnect-script is now called immediately. Previously it 530 was called, when the VPN session was terminated. 531 532- Support for building with OpenSSL 1.0.1 has been removed. The minimum 533 supported OpenSSL version is now 1.0.2. 534 535- The GET_CONFIG management state is omitted if the server pushes 536 the client configuration almost immediately as result of the 537 faster connection setup feature. 538 539- ``--compress`` is nowadays considered risky, because attacks exist 540 leveraging compression-inside-crypto to reveal plaintext (VORACLE). So 541 by default, ``--compress xxx`` will now accept incoming compressed 542 packets (for compatibility with peers that have not been upgraded yet), 543 but will not use compression outgoing packets. This can be controlled with 544 the new option ``--allow-compression yes|no|asym``. 545 546- Stop changing ``--txlen`` aways from OS defaults unless explicitly specified 547 in config file. OS defaults nowadays are actually larger then what we used 548 to configure, so our defaults sometimes caused packet drops = bad performance. 549 550- remove ``--writepid`` pid file on exit now 551 552- plugin-auth-pam now logs via OpenVPN logging method, no longer to stderr 553 (this means you'll have log messages in syslog or openvpn log file now) 554 555- use ISO 8601 time format for file based logging now (YYYY-MM-DD hh:mm:dd) 556 (syslog is not affected, nor is ``--machine-readable-output``) 557 558- ``--clr-verify`` now loads all CRLs if more than one CRL is in the same 559 file (OpenSSL backend only, mbedTLS always did that) 560 561- when ``--auth-user-pass file`` has no password, and the management interface 562 is active, query management interface (instead of trying console query, 563 which does not work on windows) 564 565- skip expired certificates in Windows certificate store (``--cryptoapicert``) 566 567- ``--socks-proxy`` + ``--proto udp*`` will now allways use IPv4, even if 568 IPv6 is requested and available. Our SOCKS code does not handle IPv6+UDP, 569 and before that change it would just fail in non-obvious ways. 570 571- TCP listen() backlog queue is now set to 32 - this helps TCP servers that 572 receive lots of "invalid" connects by TCP port scanners 573 574- do no longer print OCC warnings ("option mismatch") about ``key-method``, 575 ``keydir``, ``tls-auth`` and ``cipher`` - these are either gone now, or 576 negotiated, and the warnings do not serve a useful purpose. 577 578- ``dhcp-option DNS`` and ``dhcp-option DNS6`` are now treated identically 579 (= both accept an IPv4 or IPv6 address for the nameserver) 580 581 582Maintainer-visible changes 583-------------------------- 584- the man page is now in maintained in .rst format, so building the openvpn.8 585 manpage from a git checkout now requires python-docutils (if this is missing, 586 the manpage will not be built - which is not considered an error generally, 587 but for package builders or ``make distcheck`` it is). Release tarballs 588 contain the openvpn.8 file, so unless some .rst is changed, doc-utils are 589 not needed for building. 590 591- OCC support can no longer be disabled 592 593- AEAD support is now required in the crypto library 594 595- ``--disable-server`` has been removed from configure (so it is no longer 596 possible to build a client-/p2p-only OpenVPN binary) - the saving in code 597 size no longer outweighs the extra maintenance effort. 598 599- ``--enable-iproute2`` will disable netlink(3) support, so maybe remove 600 that from package building configs (see above) 601 602- support building with MSVC 2019 603 604- cmocka based unit tests are now only run if cmocka is installed externally 605 (2.4 used to ship a local git submodule which was painful to maintain) 606 607- ``--disable-crypto`` configure option has been removed. OpenVPN is now always 608 built with crypto support, which makes the code much easier to maintain. 609 This does not affect ``--cipher none`` to do a tunnel without encryption. 610 611- ``--disable-multi`` configure option has been removed 612 613 614 615Overview of changes in 2.4 616========================== 617 618 619New features 620------------ 621Seamless client IP/port floating 622 Added new packet format P_DATA_V2, which includes peer-id. If both the 623 server and client support it, the client sends all data packets in 624 the new format. When a data packet arrives, the server identifies peer 625 by peer-id. If peer's ip/port has changed, server assumes that 626 client has floated, verifies HMAC and updates ip/port in internal structs. 627 This allows the connection to be immediately restored, instead of requiring 628 a TLS handshake before the server accepts packets from the new client 629 ip/port. 630 631Data channel cipher negotiation 632 Data channel ciphers (``--cipher``) are now by default negotiated. If a 633 client advertises support for Negotiable Crypto Parameters (NCP), the 634 server will choose a cipher (by default AES-256-GCM) for the data channel, 635 and tell the client to use that cipher. Data channel cipher negotiation 636 can be controlled using ``--ncp-ciphers`` and ``--ncp-disable``. 637 638 A more limited version also works in client-to-server and server-to-client 639 scenarios where one of the end points uses a v2.4 client or server and the 640 other side uses an older version. In such scenarios the v2.4 side will 641 change to the ``--cipher`` set by the remote side, if permitted by by 642 ``--ncp-ciphers``. For example, a v2.4 client with ``--cipher BF-CBC`` 643 and ``ncp-ciphers AES-256-GCM:AES-256-CBC`` can connect to both a v2.3 644 server with ``cipher BF-CBC`` as well as a server with 645 ``cipher AES-256-CBC`` in its config. The other way around, a v2.3 client 646 with either ``cipher BF-CBC`` or ``cipher AES-256-CBC`` can connect to a 647 v2.4 server with e.g. ``cipher BF-CBC`` and 648 ``ncp-ciphers AES-256-GCM:AES-256-CBC`` in its config. For this to work 649 it requires that OpenVPN was built without disabling OCC support. 650 651AEAD (GCM) data channel cipher support 652 The data channel now supports AEAD ciphers (currently only GCM). The AEAD 653 packet format has a smaller crypto overhead than the CBC packet format, 654 (e.g. 20 bytes per packet for AES-128-GCM instead of 36 bytes per packet 655 for AES-128-CBC + HMAC-SHA1). 656 657ECDH key exchange 658 The TLS control channel now supports for elliptic curve diffie-hellmann 659 key exchange (ECDH). 660 661Improved Certificate Revocation List (CRL) processing 662 CRLs are now handled by the crypto library (OpenSSL or mbed TLS), instead 663 of inside OpenVPN itself. The crypto library implementations are more 664 strict than the OpenVPN implementation was. This might reject peer 665 certificates that would previously be accepted. If this occurs, OpenVPN 666 will log the crypto library's error description. 667 668Dualstack round-robin DNS client connect 669 Instead of only using the first address of each ``--remote`` OpenVPN 670 will now try all addresses (IPv6 and IPv4) of a ``--remote`` entry. 671 672Support for providing IPv6 DNS servers 673 A new DHCP sub-option ``DNS6`` is added alongside with the already existing 674 ``DNS`` sub-option. This is used to provide DNS resolvers available over 675 IPv6. This may be pushed to clients where `` --up`` scripts and ``--plugin`` 676 can act upon it through the ``foreign_option_<n>`` environment variables. 677 678 Support for the Windows client picking up this new sub-option is added, 679 however IPv6 DNS resolvers need to be configured via ``netsh`` which requires 680 administrator privileges unless the new interactive services on Windows is 681 being used. If the interactive service is used, this service will execute 682 ``netsh`` in the background with the proper privileges. 683 684New improved Windows Background service 685 The new OpenVPNService is based on openvpnserv2, a complete rewrite of the OpenVPN 686 service wrapper. It is intended for launching OpenVPN instances that should be 687 up at all times, instead of being manually launched by a user. OpenVPNService is 688 able to restart individual OpenVPN processes if they crash, and it also works 689 properly on recent Windows versions. OpenVPNServiceLegacy tends to work poorly, 690 if at all, on newer Windows versions (8+) and its use is not recommended. 691 692New interactive Windows service 693 The installer starts OpenVPNServiceInteractive automatically and configures 694 it to start at system startup. 695 696 The interactive Windows service allows unprivileged users to start 697 OpenVPN connections in the global config directory (usually 698 C:\\Program Files\\OpenVPN\\config) using OpenVPN GUI without any 699 extra configuration. 700 701 Users who belong to the built-in Administrator group or to the 702 local "OpenVPN Administrator" group can also store configuration 703 files under %USERPROFILE%\\OpenVPN\\config for use with the 704 interactive service. 705 706redirect-gateway ipv6 707 OpenVPN has now feature parity between IPv4 and IPv6 for redirect 708 gateway including the handling of overlapping IPv6 routes with 709 IPv6 remote VPN server address. 710 711LZ4 Compression and pushable compression 712 Additionally to LZO compression OpenVPN now also supports LZ4 compression. 713 Compression options are now pushable from the server. 714 715Filter pulled options client-side: pull-filter 716 New option to explicitly allow or reject options pushed by the server. 717 May be used multiple times and is applied in the order specified. 718 719Per-client remove push options: push-remove 720 New option to remove options on a per-client basis from the "push" list 721 (more fine-grained than ``--push-reset``). 722 723Http proxy password inside config file 724 Http proxy passwords can be specified with the inline file option 725 ``<http-proxy-user-pass>`` .. ``</http-proxy-user-pass>`` 726 727Windows version detection 728 Windows version is detected, logged and possibly signalled to server 729 (IV_PLAT_VER=<nn> if ``--push-peer-info`` is set on client). 730 731Authentication tokens 732 In situations where it is not suitable to save user passwords on the client, 733 OpenVPN has support for pushing a --auth-token since v2.3. This option is 734 pushed from the server to the client with a token value to be used instead 735 of the users password. For this to work, the authentication plug-in would 736 need to implement this support as well. In OpenVPN 2.4 --auth-gen-token 737 is introduced, which will allow the OpenVPN server to generate a random 738 token and push it to the client without any changes to the authentication 739 modules. When the clients need to re-authenticate the OpenVPN server will 740 do the authentication internally, instead of sending the re-authentication 741 request to the authentication module . This feature is especially 742 useful in configurations which use One Time Password (OTP) authentication 743 schemes, as this allows the tunnel keys to be renegotiated regularly without 744 any need to supply new OTP codes. 745 746keying-material-exporter 747 Keying Material Exporter [RFC-5705] allow additional keying material to be 748 derived from existing TLS channel. 749 750Android platform support 751 Support for running on Android using Android's VPNService API has been added. 752 See doc/android.txt for more details. This support is primarily used in 753 the OpenVPN for Android app (https://github.com/schwabe/ics-openvpn) 754 755AIX platform support 756 AIX platform support has been added. The support only includes tap 757 devices since AIX does not provide tun interface. 758 759Control channel encryption (``--tls-crypt``) 760 Use a pre-shared static key (like the ``--tls-auth`` key) to encrypt control 761 channel packets. Provides more privacy, some obfuscation and poor-man's 762 post-quantum security. 763 764Asynchronous push reply 765 Plug-ins providing support for deferred authentication can benefit from a more 766 responsive authentication where the server sends PUSH_REPLY immediately once 767 the authentication result is ready, instead of waiting for the the client to 768 to send PUSH_REQUEST once more. This requires OpenVPN to be built with 769 ``./configure --enable-async-push``. This is a compile-time only switch. 770 771 772Deprecated features 773------------------- 774For an up-to-date list of all deprecated options, see this wiki page: 775https://community.openvpn.net/openvpn/wiki/DeprecatedOptions 776 777- ``--key-method 1`` is deprecated in OpenVPN 2.4 and will be removed in v2.5. 778 Migrate away from ``--key-method 1`` as soon as possible. The recommended 779 approach is to remove the ``--key-method`` option from the configuration 780 files, OpenVPN will then use ``--key-method 2`` by default. Note that this 781 requires changing the option in both the client and server side configs. 782 783- ``--tls-remote`` is removed in OpenVPN 2.4, as indicated in the v2.3 784 man-pages. Similar functionality is provided via ``--verify-x509-name``, 785 which does the same job in a better way. 786 787- ``--compat-names`` and ``--no-name-remapping`` were deprecated in OpenVPN 2.3 788 and will be removed in v2.5. All scripts and plug-ins depending on the old 789 non-standard X.509 subject formatting must be updated to the standardized 790 formatting. See the man page for more information. 791 792- ``--no-iv`` is deprecated in OpenVPN 2.4 and will be removed in v2.5. 793 794- ``--keysize`` is deprecated in OpenVPN 2.4 and will be removed in v2.6 795 together with the support of ciphers with cipher block size less than 796 128-bits. 797 798- ``--comp-lzo`` is deprecated in OpenVPN 2.4. Use ``--compress`` instead. 799 800- ``--ifconfig-pool-linear`` has been deprecated since OpenVPN 2.1 and will be 801 removed in v2.5. Use ``--topology p2p`` instead. 802 803- ``--client-cert-not-required`` is deprecated in OpenVPN 2.4 and will be removed 804 in v2.5. Use ``--verify-client-cert none`` for a functional equivalent. 805 806- ``--ns-cert-type`` is deprecated in OpenVPN 2.3.18 and v2.4. It will be removed 807 in v2.5. Use the far better ``--remote-cert-tls`` option which replaces this 808 feature. 809 810 811User-visible Changes 812-------------------- 813- When using ciphers with cipher blocks less than 128-bits, 814 OpenVPN will complain loudly if the configuration uses ciphers considered 815 weak, such as the SWEET32 attack vector. In such scenarios, OpenVPN will by 816 default renegotiate for each 64MB of transported data (``--reneg-bytes``). 817 This renegotiation can be disabled, but is HIGHLY DISCOURAGED. 818 819- For certificate DNs with duplicate fields, e.g. "OU=one,OU=two", both fields 820 are now exported to the environment, where each second and later occurrence 821 of a field get _$N appended to it's field name, starting at N=1. For the 822 example above, that would result in e.g. X509_0_OU=one, X509_0_OU_1=two. 823 Note that this breaks setups that rely on the fact that OpenVPN would 824 previously (incorrectly) only export the last occurrence of a field. 825 826- ``proto udp`` and ``proto tcp`` now use both IPv4 and IPv6. The new 827 options ``proto udp4`` and ``proto tcp4`` use IPv4 only. 828 829- ``--sndbuf`` and ``--recvbuf`` default now to OS defaults instead of 64k 830 831- OpenVPN exits with an error if an option has extra parameters; 832 previously they were silently ignored 833 834- ``--tls-auth`` always requires OpenVPN static key files and will no 835 longer work with free form files 836 837- ``--proto udp6/tcp6`` in server mode will now try to always listen to 838 both IPv4 and IPv6 on platforms that allow it. Use ``--bind ipv6only`` 839 to explicitly listen only on IPv6. 840 841- Removed ``--enable-password-save`` from configure. This option is now 842 always enabled. 843 844- Stricter default TLS cipher list (override with ``--tls-cipher``), that now 845 also disables: 846 847 * Non-ephemeral key exchange using static (EC)DH keys 848 * DSS private keys 849 850- mbed TLS builds: changed the tls_digest_N values exported to the script 851 environment to be equal to the ones exported by OpenSSL builds, namely 852 the certificate fingerprint (was the hash of the 'to be signed' data). 853 854- mbed TLS builds: minimum RSA key size is now 2048 bits. Shorter keys will 855 not be accepted, both local and from the peer. 856 857- ``--connect-timeout`` now specifies the timeout until the first TLS packet 858 is received (identical to ``--server-poll-timeout``) and this timeout now 859 includes the removed socks proxy timeout and http proxy timeout. 860 861 In ``--static`` mode ``connect-timeout`` specifies the timeout for TCP and 862 proxy connection establishment 863 864- ``--connect-retry-max`` now specifies the maximum number of unsuccessful 865 attempts of each remote/connection entry before exiting. 866 867- ``--http-proxy-timeout`` and the static non-changeable socks timeout (5s) 868 have been folded into a "unified" ``--connect-timeout`` which covers all 869 steps needed to connect to the server, up to the start of the TLS exchange. 870 The default value has been raised to 120s, to handle slow http/socks 871 proxies graciously. The old "fail TCP fast" behaviour can be achieved by 872 adding "``--connect-timeout 10``" to the client config. 873 874- ``--http-proxy-retry`` and ``--sock-proxy-retry`` have been removed. Proxy connections 875 will now behave like regular connection entries and generate a USR1 on failure. 876 877- ``--connect-retry`` gets an optional second argument that specifies the maximum 878 time in seconds to wait between reconnection attempts when an exponential 879 backoff is triggered due to repeated retries. Default = 300 seconds. 880 881- Data channel cipher negotiation (see New features section) can override 882 ciphers configured in the config file. Use ``--ncp-disable`` if you do not want 883 this behavior. 884 885- All tun devices on all platforms are always considered to be IPv6 886 capable. The ``--tun-ipv6`` option is ignored (behaves like it is always 887 on). 888 889- On the client side recursively routed packets, which have the same destination 890 as the VPN server, are dropped. This can be disabled with 891 --allow-recursive-routing option. 892 893- On Windows, when the ``--register-dns`` option is set, OpenVPN no longer 894 restarts the ``dnscache`` service - this had unwanted side effects, and 895 seems to be no longer necessary with currently supported Windows versions. 896 897- If no flags are given, and the interactive Windows service is used, "def1" 898 is implicitly set (because "delete and later reinstall the existing 899 default route" does not work well here). If not using the service, 900 the old behaviour is kept. 901 902- OpenVPN now reloads a CRL only if the modication time or file size has 903 changed, instead of for each new connection. This reduces the connection 904 setup time, in particular when using large CRLs. 905 906- OpenVPN now ships with more up-to-date systemd unit files which take advantage 907 of the improved service management as well as some hardening steps. The 908 configuration files are picked up from the /etc/openvpn/server/ and 909 /etc/openvpn/client/ directories (depending on unit file). This also avoids 910 these new unit files and how they work to collide with older pre-existing 911 unit files. 912 913- Using ``--no-iv`` (which is generally not a recommended setup) will 914 require explicitly disabling NCP with ``--disable-ncp``. This is 915 intentional because NCP will by default use AES-GCM, which requires 916 an IV - so we want users of that option to consciously reconsider. 917 918 919Maintainer-visible changes 920-------------------------- 921- OpenVPN no longer supports building with crypto support, but without TLS 922 support. As a consequence, OPENSSL_CRYPTO_{CFLAGS,LIBS} and 923 OPENSSL_SSL_{CFLAGS,LIBS} have been merged into OPENSSL_{CFLAGS,LIBS}. This 924 is particularly relevant for maintainers who build their own OpenSSL library, 925 e.g. when cross-compiling. 926 927- Linux distributions using systemd is highly encouraged to ship these new unit 928 files instead of older ones, to provide a unified behaviour across systemd 929 based Linux distributions. 930 931- With OpenVPN 2.4, the project has moved over to depend on and actively use 932 the official C99 standard (-std=c99). This may fail on some older compiler/libc 933 header combinations. In most of these situations it is recommended to 934 use -std=gnu99 in CFLAGS. This is known to be needed when doing 935 i386/i686 builds on RHEL5. 936 937 938Version 2.4.5 939============= 940 941New features 942------------ 943- The new option ``--tls-cert-profile`` can be used to restrict the set of 944 allowed crypto algorithms in TLS certificates in mbed TLS builds. The 945 default profile is 'legacy' for now, which allows SHA1+, RSA-1024+ and any 946 elliptic curve certificates. The default will be changed to the 'preferred' 947 profile in the future, which requires SHA2+, RSA-2048+ and any curve. 948 949 950Version 2.4.3 951============= 952 953New features 954------------ 955- Support building with OpenSSL 1.1 now (in addition to older versions) 956 957- On Win10, set low interface metric for TAP adapter when block-outside-dns 958 is in use, to make Windows prefer the TAP adapter for DNS queries 959 (avoiding large delays) 960 961 962Security 963-------- 964- CVE-2017-7522: Fix ``--x509-track`` post-authentication remote DoS 965 A client could crash a v2.4+ mbedtls server, if that server uses the 966 ``--x509-track`` option and the client has a correct, signed and unrevoked 967 certificate that contains an embedded NUL in the certificate subject. 968 Discovered and reported to the OpenVPN security team by Guido Vranken. 969 970- CVE-2017-7521: Fix post-authentication remote-triggerable memory leaks 971 A client could cause a server to leak a few bytes each time it connects to the 972 server. That can eventually cause the server to run out of memory, and thereby 973 causing the server process to terminate. Discovered and reported to the 974 OpenVPN security team by Guido Vranken. (OpenSSL builds only.) 975 976- CVE-2017-7521: Fix a potential post-authentication remote code execution 977 attack on servers that use the ``--x509-username-field`` option with an X.509 978 extension field (option argument prefixed with ``ext:``). A client that can 979 cause a server to run out-of-memory (see above) might be able to cause the 980 server to double free, which in turn might lead to remote code execution. 981 Discovered and reported to the OpenVPN security team by Guido Vranken. 982 (OpenSSL builds only.) 983 984- CVE-2017-7520: Pre-authentication remote crash/information disclosure for 985 clients. If clients use a HTTP proxy with NTLM authentication (i.e. 986 ``--http-proxy <server> <port> [<authfile>|'auto'|'auto-nct'] ntlm2``), 987 a man-in-the-middle attacker between the client and the proxy can cause 988 the client to crash or disclose at most 96 bytes of stack memory. The 989 disclosed stack memory is likely to contain the proxy password. If the 990 proxy password is not reused, this is unlikely to compromise the security 991 of the OpenVPN tunnel itself. Clients who do not use the ``--http-proxy`` 992 option with ntlm2 authentication are not affected. 993 994- CVE-2017-7508: Fix remotely-triggerable ASSERT() on malformed IPv6 packet. 995 This can be used to remotely shutdown an openvpn server or client, if 996 IPv6 and ``--mssfix`` are enabled and the IPv6 networks used inside the VPN 997 are known. 998 999- Fix null-pointer dereference when talking to a malicious http proxy 1000 that returns a malformed ``Proxy-Authenticate:`` headers for digest auth. 1001 1002- Fix overflow check for long ``--tls-cipher`` option 1003 1004- Windows: Pass correct buffer size to ``GetModuleFileNameW()`` 1005 (OSTIF/Quarkslabs audit, finding 5.6) 1006 1007 1008User-visible Changes 1009-------------------- 1010- ``--verify-hash`` can now take an optional flag which changes the hashing 1011 algorithm. It can be either SHA1 or SHA256. The default if not provided is 1012 SHA1 to preserve backwards compatibility with existing configurations. 1013 1014- Restrict the supported ``--x509-username-field`` extension fields to subjectAltName 1015 and issuerAltName. Other extensions probably didn't work anyway, and would 1016 cause OpenVPN to crash when a client connects. 1017 1018 1019Bugfixes 1020-------- 1021- Fix fingerprint calculation in mbed TLS builds. This means that mbed TLS users 1022 of OpenVPN 2.4.0, v2.4.1 and v2.4.2 that rely on the values of the 1023 ``tls_digest_*`` env vars, or that use ``--verify-hash`` will have to change 1024 the fingerprint values they check against. The security impact of the 1025 incorrect calculation is very minimal; the last few bytes (max 4, typically 1026 4) are not verified by the fingerprint. We expect no real-world impact, 1027 because users that used this feature before will notice that it has suddenly 1028 stopped working, and users that didn't will notice that connection setup 1029 fails if they specify correct fingerprints. 1030 1031- Fix edge case with NCP when the server sends an empty PUSH_REPLY message 1032 back, and the client would not initialize it's data channel crypto layer 1033 properly (trac #903) 1034 1035- Fix SIGSEGV on unaligned buffer access on OpenBSD/Sparc64 1036 1037- Fix TCP_NODELAY on OpenBSD 1038 1039- Remove erroneous limitation on max number of args for ``--plugin`` 1040 1041- Fix NCP behaviour on TLS reconnect (Server would not send a proper 1042 "cipher ..." message back to the client, leading to client and server 1043 using different ciphers) (trac #887) 1044 1045 1046Version 2.4.2 1047============= 1048 1049Bugfixes 1050-------- 1051- Fix memory leak introduced in OpenVPN 2.4.1: if ``--remote-cert-tls`` is 1052 used, we leaked some memory on each TLS (re)negotiation. 1053 1054 1055Security 1056-------- 1057- Fix a pre-authentication denial-of-service attack on both clients and 1058 servers. By sending a too-large control packet, OpenVPN 2.4.0 or v2.4.1 can 1059 be forced to hit an ASSERT() and stop the process. If ``--tls-auth`` or 1060 ``--tls-crypt`` is used, only attackers that have the ``--tls-auth`` or 1061 ``--tls-crypt`` key can mount an attack. 1062 (OSTIF/Quarkslab audit finding 5.1, CVE-2017-7478) 1063 1064- Fix an authenticated remote DoS vulnerability that could be triggered by 1065 causing a packet id roll over. An attack is rather inefficient; a peer 1066 would need to get us to send at least about 196 GB of data. 1067 (OSTIF/Quarkslab audit finding 5.2, CVE-2017-7479) 1068 1069 1070Version 2.4.1 1071============= 1072- ``--remote-cert-ku`` now only requires the certificate to have at least the 1073 bits set of one of the values in the supplied list, instead of requiring an 1074 exact match to one of the values in the list. 1075- ``--remote-cert-tls`` now only requires that a keyUsage is present in the 1076 certificate, and leaves the verification of the value up to the crypto 1077 library, which has more information (i.e. the key exchange method in use) 1078 to verify that the keyUsage is correct. 1079- ``--ns-cert-type`` is deprecated. Use ``--remote-cert-tls`` instead. 1080 The nsCertType x509 extension is very old, and barely used. 1081 ``--remote-cert-tls`` uses the far more common keyUsage and extendedKeyUsage 1082 extension instead. Make sure your certificates carry these to be able to 1083 use ``--remote-cert-tls``. 1084 1085