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openvpn/Changes.rst
Selva Nair 5d429efd97 Exponentially back off on repeated connect retries 
- When the number of retries per remote exceeds a limit
  (hard coded to 5), double the restart pause interval
  for each additional retry per remote.
- Trigger a SIGHUP to reset the retry count when the pause
  interval exceeds 1024 times the base value of restart pause.
  (removed in v2 of the patch)

The base value of restart pause is set using --connect-retry
(5 seconds by default).

v2 changes (based on suggestions from Arne Schwabe <arne@rfc2549.org>)

- Do not throw SIGHUP.
- Add an optional argument to "--connect-retry n [m]" where 'm'
  specifies the max value of restart pause interval (default
  300 sec).
  E.g., "--connect-retry 5 1800" will cause the restart pause to
  scale up starting at 5 until it exceeds 1800 seconds at which
  point it gets capped at 1800.
- If n == m no slow down will occur.
- While at it, fix typos and clarify the description of connect-retry-max
  in the man page and Changes.rst

v3 changes (on further feedback from arne@rfc2549.org):
- Limiting the base value of retry wait interval to 16 bits moved
  to options.c
- Apply backoff only in the udp and tcp-client modes. Backing off on
  tcp-server could be exploited by a client in p2p-mode to maliciously
  slow it down (thanks to Arne Schwabe for pointing this out.
- Fix typo in Changes.rst: "third argument" -> "second argument"

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1467732770-19110-1-git-send-email-selva.nair@gmail.com>
URL: http://article.gmane.org/gmane.network.openvpn.devel/12050
Signed-off-by: Gert Doering <gert@greenie.muc.de>
2016-07-11 16:19:12 +02:00

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Version 2.4.0
=============
New features
------------
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)
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).
Http proxy password inside config file
Http proxy passwords can be specified with the inline file option
http-proxy-user-pass
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-max now specifies the maximum number of unsuccessful
attempts of each remote/connection entry 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.
- --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.
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.
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