openvpn/Changes.rst

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Version 2.4.0
=============
New features
------------
Add an option to filter options received from server v2 changes: - Add the flag "ignore" and have "reject" trigger a restart. - Unlimited number of filters: yes, going against the consensus, but the code looks simpler and cleaner this way. - New commit message to reflect the changes. Usage: --pull-filter accept|ignore|reject "option" Permit a client to selectively accept, ignore or reject options pushed by the server. May be used multiple times. The filters are applied in the order specified to each pushed option received. The filtering stops as soon as a match is found. The action "ignore" removes the option and continues processing the next option, while "reject" flags an error and restarts the connection with SIGUSR1. Prefix matching is used so that all options starting with the specified "option" string are filtered. Example: pull-filter accept "route 192.168." pull-filter ignore "route " pull-filter accept "ifconfig 10.9.0." pull-filter reject "ifconfig " will ignore all pushed routes except those starting with "192.168." and reject the assigned ip unless its in the "10.9.0.0/24" range. A match of the reject filter will trigger a restart. SIGUSR1 restart is used instead of SIGHUP so as to try the next remote for reconnection. Note the space at the end of "route " to not reject "route-gateway", for example. All options not matched by any filter are accepted. Acknowledges shameless imitation of --push-remove. Inspired by Trac #682. Signed-off-by: Selva Nair <selva.nair@gmail.com> Acked-by: Gert Doering <gert@greenie.muc.de> Message-Id: <1465162884-32520-1-git-send-email-selva.nair@gmail.com> URL: http://article.gmane.org/gmane.network.openvpn.devel/11808 Signed-off-by: Gert Doering <gert@greenie.muc.de>
2016-06-06 05:41:23 +08:00
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")
keying-material-exporter
Keying Material Exporter [RFC-5705] allow additional keying material to be
derived from existing TLS channel.
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
Mac OS X Keychain management client
add contrib/keychain-mcd which allows to use Mac OS X keychain
certificates with OpenVPN
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.
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.
LZ4 Compression
Additionally to LZO compression OpenVPN now also supports LZ4
compression.
Windows version
Windows version is detected, logged and possibly signalled to server
(IV_PLAT_VER=<nn> if --push-peer-info is set on client)
Add AEAD cipher support (GCM) Add Authenticated Encryption with Additional Data (AEAD) support for ciphers, which removes the need for a separate HMAC step. The MAC is integrated into the cipher and the MAC tag is prepended to the payload. This patch is inspired by the patch originally submitted by Kenny Root on the openvpn-devel mailinglist, but does a number things differently: * Don't support XTS (makes no sense for VPN) * Don't support CCM (needs extra code to make it actually work) * Don't force the user to specify "auth none" (that would break tls-auth) * Add support for PolarSSL (and change internal API for this) * Update openvpn frame size ('link mtu') calculation for AEAD modes * Use the HMAC key as an implicit part of the IV to save 8 bytes per data channel network packet. * Also authenticate the opcode/peer-id as AD in P_DATA_V2 packets. By using the negotiated HMAC key as an implicit part of the IV for AEAD-mode ciphers in TLS mode, we can save (at least) 8 bytes on each packet sent. This is particularly interesting for connections which transfer many small packets, such as remote desktop or voip connections. The current AEAD-mode ciphers (for now GCM) are based on CTR-mode cipher operation, which requires the IV to be unique (but does not require unpredictability). IV uniqueness is guaranteed by using a combination of at least 64-bits of the HMAC key (unique per TLS session), and a 32-bit packet counter. The last 32-bit word of the 128-bit cipher block is not part of the IV, but is used as a block counter. AEAD cipher mode is not available for static key mode, since IV uniqueness is harder the guarantee over sessions, and I believe supporting AEAD in static key mode too is not worth the extra complexity. Modern setups should simply use TLS mode. OpenSSL 1.0.1-1.0.1c will not work with AEAD mode, because those versions have an unnecessary check that fails to update the cipher if the tag was not already set. 1.0.1d, which fixes that, was released in February 2013. People should have updated, and distros should have backported the fix by now. Changes in v2: * Remove extra code that was just for making OpenSSL 1.0.1-1.0.1c work in AEAD mode. * Do not make AEAD support configurable in ./configure. * Get rid of '12' magic constant in openvpn_encrypt_aead(). * Update manpage to explain that --auth is ignored for the data channel when using an AEAD cipher. * Move setting the IV in AEAD cipher modes to the IV generation code. This is a more natural place and now we can pull iv[] into the IV generation scope. * Read packet ID directly from packet buffer instead of from iv buffer, to remove the need for an extra buffer. Signed-off-by: Steffan Karger <steffan@karger.me> Acked-by: Arne Schwabe <arne@rfc2549.org> Message-Id: <CAA1AbxL_S4umZr5Nd0VTvUvXEHjoWmji18GqM6FgmWqntOKqaA@mail.gmail.com> URL: http://article.gmane.org/gmane.network.openvpn.devel/11162 Signed-off-by: Gert Doering <gert@greenie.muc.de>
2015-10-24 22:44:09 +08:00
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).
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.
- 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 now specifies the maximum number of unsucessfully
trying all remote/connection entries before exiting.
- sndbuf and recvbuf default now to OS default 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.
- --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.
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.