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2024.84 - 4 April 2024
Features and Changes:
Note >> for compatibility/configuration changes
- >> Only use /etc/shadow when a user has :x: as the crypt in /etc/passwd.
This is the documented behaviour of passwd(5) so should be consistent with
other programs. Thanks to Paulo Cabral for the report.
Note that any users without x as the crypt will not be able
to log in with /etc/shadow, in cases were the existing configuration
differs.
- Support -o StrictHostKeyChecking, patch from Sergey Ponomarev
- Support -o BatchMode, from Sergey Ponomarev and Hans Harder
- Support various other -o options compatible with OpenSSH, from
Sergey Ponomarev. Includes -o PasswordAuthentication
- Add dbclient config file support, ~/.ssh/dropbear_config
Thanks to tjkolev
Disabled by default, set #define DROPBEAR_USE_SSH_CONFIG 1
- Add support for unix socket forwarding (destination) on
the server, thanks to WangYi for the implementation
- Add option to bind to interface, from Diederik De Coninck
- Ignore unsupported arguments in dropbearkey, allow running
binary as 'ssh-key'. From Sergey Ponomarev
- Save a public key file on generation with dropbearkey.
-C can be used for a comment, and choose a default key
type (ed25519 first preference).
Thanks to Sergey Ponomarev
- Allow inetd to run in non-syslog modes. Thanks to Laurent Bercot
for the report
- Allow user's own gid in PTY permissions, lets Dropbear work as non-root
even if /dev/pts isn't mounted with gid=5
- src/distrooptions.h can now be used as another config file.
This can be used by distributions for customisations (separate
to the build directory's localoptions.h)
Fixes:
- "dbclient host >> output" would previously overwrite "output", instead of
appending. Thanks for the report from eSotoIoT
- Add "Strict KEX" support. This mitigates a SSH protocol flaw which lets
a MITM attacker silently remove packets immediately after the
first key exchange. At present the flaw does not seem to reduce Dropbear's
security (the only packet affected would be a server-sig-algs extension,
which is used for compatibility not security).
For Dropbear, chacha20-poly1305 is the only affected cipher.
Both sides of the connection must support Strict KEX for it to be used.
The protocol flaw is tracked as CVE-2023-48795, details
at https://terrapin-attack.com . Thanks to the researchers Fabian Bäumer,
Marcus Brinkmann, and Jörg Schwenk. Thanks to OpenSSH for specifying
strict KEX mode.
- Fix blocking while closing forwarded TCP sessions. Noticable
when many connections are being forwarded. Reported and
tested by GektorUA. Github #230
- Don't offer RSA (then fail) if there is no RSA key. Regression in 2020.79
Github #219
- Fix missing response to remote TCP requests when it is disabled.
Patch from Justin Chen. Github #254
- Fix building with DROPBEAR_RSA disabled
- /proc/timer_list is no longer used for entropy, it was a bottleneck.
Thanks to Aleksei Plotnikov for the report.
- Don't unconditionally enable DROPBEAR_DSS
- Make banner reading failure non-fatal
- Fix DROPBEAR_SVR_MULTIUSER. This appears to have been broken since when it
was added in 2019. If you're using this let me know (it might be removed
if I don't hear otherwise). Thanks to davidatrsp
- Fix Y2038 issues
Infrastructure:
- Move source files to src/ subdirectory. Thanks to tjkolev
- Remove more files with "make distclean"
- Add tests for disabled options
2022.83 - 14 November 2022
Features and Changes:
Note >> for compatibility/configuration changes
- >> Disable DROPBEAR_DSS by default
It is only 1024 bit and uses sha1, most distros disable it by default already.
- Added DROPBEAR_RSA_SHA1 option to allow disabling sha1 rsa signatures.
>> RSA with sha1 will be disabled in a future release (rsa keys will continue
to work OK, with sha256 signatures used instead).
- Add option for requiring both password and pubkey (-t)
Patch from Jackkal
- Add 'no-touch-required' and 'verify-required' options for sk keys
Patch from Egor Duda
- >> DROPBEAR_SK_KEYS config option now replaces separate DROPBEAR_SK_ECDSA
and DROPBEAR_SK_ED25519 options.
- Add 'permitopen' option for authorized_keys to restrict forwarded ports
Patch from Tuomas Haikarainen
- >> Added LTM_CFLAGS configure argument to set flags for building
bundled libtommath. This also restores the previous arguments used
in 2020.81 (-O3 -funroll-loops). That gives a big speedup for RSA
key generation, which regressed in 2022.82.
There is a tradeoff with code size, so -Os can be used if required.
https://github.com/mkj/dropbear/issues/174
Reported by David Bernard
- Add '-z' flag to disable setting QoS traffic class. This may be necessary
to work with broken networks or network drivers, exposed after changes to use
AF21 in 2022.82
https://github.com/mkj/dropbear/issues/193
Reported by yuhongwei380, patch from Petr Štetiar
- Allow overriding user shells with COMPAT_USER_SHELLS
Based on a patch from Matt Robinson
- Improve permission error message
Patch from k-kurematsu
- >> Remove HMAC_MD5 entirely
Regression fixes from 2022.82:
- Fix X11 build
- Fix build warning
- Fix compilation when disabling pubkey authentication
Patch from MaxMougg
- Fix MAX_UNAUTH_CLIENTS regression
Reported by ptpt52
- Avoid using slower prime testing in bundled libtomcrypt when DSS is disabled
https://github.com/mkj/dropbear/issues/174
Suggested by Steffen Jaeckel
- Fix Dropbear plugin support
https://github.com/mkj/dropbear/issues/194
Reported by Struan Bartlett
Other fixes:
- Fix long standing incorrect compression size check. Dropbear
(client or server) would erroneously exit with
"bad packet, oversized decompressed"
when receiving a compressed packet of exactly the maximum size.
- Fix missing setsid() removed in 2020.79
https://github.com/mkj/dropbear/issues/180
Reported and debugged by m5jt and David Bernard
- Try keyboard-interactive auth before password, in dbclient.
This was unintentionally changed back in 2013
https://github.com/mkj/dropbear/pull/190
Patch from Michele Giacomoli
- Drain the terminal when reading the fingerprint confirmation response
https://github.com/mkj/dropbear/pull/191
Patch from Michele Giacomoli
- Fix utx wtmp variable typo. This has been wrong for a long time but
only recently became a problem when wtmp was detected.
https://github.com/mkj/dropbear/pull/189
Patch from Michele Giacomoli
- Improve configure test for hardening options.
Fixes building on AIX
https://github.com/mkj/dropbear/issues/158
- Fix debian/dropbear.init newline
From wulei-student
Infrastructure:
- Test off-by-default compile options
- Set -Wundef to catch typos in #if statements
2022.82 - 1 April 2022
Features and Changes:
Note >> for compatibility/configuration changes
- Implemented OpenSSH format private key handling for dropbearconvert.
Keys can be read in OpenSSH format or the old PEM format.
>> Keys are now written in OpenSSH format rather than PEM.
ED25519 support is now correct. DSS keys are still PEM format.
- Use SHA256 for key fingerprints
- >> Reworked -v verbose printing, specifying multiple times will increase
verbosity. -vvvv is equivalent to the old DEBUG_TRACE -v level, it
can be configured at compile time in localoptions.h (see default_options.h)
Lower -v options can be used to check connection progress or algorithm
negotiation.
Thanks to Hans Harder for the implementation
localoptions.h DEBUG_TRACE should be set to 4 for the same result as the
previous DEBUG_TRACE 1.
- Added server support for U2F/FIDO keys (ecdsa-sk and ed25519-sk) in
authorized_keys. no-touch-required option isn't allowed yet.
Thanks to Egor Duda for the implementation
- autoconf output (configure script etc) is now committed to version control.
>> It isn't necessary to run "autoconf" any more on a checkout.
- sha1 will be omitted from the build if KEX/signing/MAC algorithms don't
require it. Instead sha256 is used for random number generation.
See sysoptions.h to see which algorithms require which hashes.
- Set SSH_PUBKEYINFO environment variable based on the authorized_keys
entry used for auth. The first word of the comment after the key is used
(must only have characters a-z A-Z 0-9 .,_-+@)
Patch from Hans Harder, modified by Matt Johnston
- Let dbclient multihop mode be used with '-J'.
Patch from Hans Harder
- Allow home-directory relative paths ~/path for various settings
and command line options.
*_PRIV_FILENAME DROPBEAR_PIDFILE SFTPSERVER_PATH MOTD_FILENAME
Thanks to Begley Brothers Inc
>> The default DROPBEAR_DEFAULT_CLI_AUTHKEY has now changed, it now needs
a tilde prefix.
- LANG environment variable is carried over from the Dropbear server process
From Maxim Kochetkov
- Add /usr/sbin and /sbin to $PATH when logging in as root.
Patch from Raphaël Hertzog
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=903403
- Added client option "-o DisableTrivialAuth". It disallows a server immediately
giving successful authentication (without presenting any password/pubkey prompt).
This avoids a UI confusion issue where it may appear that the user is accepting
a SSH agent prompt from their local machine, but are actually accepting a prompt
sent immediately by the remote server.
CVE-2021-36369 though the description there is a bit confused. It only applies
to Dropbear as a client.
Thanks to Manfred Kaiser from Austrian MilCERT
- Add -q client option to hide remote banner, from Hans Harder
- Add -e option to pass all server environment variables to child processes.
This should be used with caution.
Patch from Roland Vollgraf (github #118)
- >> Use DSCP for QoS traffic classes. Priority (tty) traffic is now set to
AF21 "interactive". Previously TOS classes were used, they are not used by
modern traffic classifiers. Non-tty traffic is left at default priority.
- >> Disable dh-group1 key exchange by default. It has been disabled server
side by default since 2018.
- >> Removed Twofish cipher
Fixes:
- Fix flushing channel data when pty was allocated (github #85)
Data wasn't completely transmitted at channel close.
Reported and initial patch thanks to Yousong Zhou
- Dropbear now re-executes itself rather than just forking for each connection
(only on Linux). This allows ASLR to randomise address space for each
connection as a security mitigation. It should not have any visible impact
- if there are any performance impacts in the wild please report it.
- Check authorized_keys permissions as the user, fixes NFS squash root.
Patch from Chris Dragan (github #107)
- A missing home directory is now non-fatal, starting in / instead
- Fixed IPv6 [address]:port parsing for dbclient -b
Reported by Fabio Molinari
- Improve error logging so that they are logged on the server rather than being
sent to the client over the connection
- Max window size is increased to 10MB, more graceful fallback if it's invalid.
- Fix correctness of Dropbear's handling of global requests.
Patch from Dirkjan Bussink
- Fix some small bugs found by fuzzers, null pointer dereference crash and leaks
(post authentication)
- $HOME variable is used before /etc/passwd when expanding paths such as
~/.ssh/id_dropbear (for the client). Patch from Matt Robinson
- C89 build fixes from Guillaume Picquet
Infrastructure:
- Improvements to fuzzers. Added post-auth fuzzer, and a mutator that can
handle the structure of SSH packet streams. Added cifuzz to run on commits
and pull requests.
Thanks to OSS-Fuzz for the tools/clusters and reward funding.
- Dropbear source tarballs generated by release.sh are now reproducible from a
Git or Mercurial checkout, they will be identical on any system. Tested
on ubuntu and macos.
- Added some integration testing using pytest. Currently this has tests
for various channel handling edge cases, ASLR fork randomisation,
dropbearconvert, and SSH_PUBKEYINFO
- Set up github actions. This runs the pytest suite and other checks.
- build matrix includes c89, dropbearmulti, bundled libtom, macos, DEBUG_TRACE
- test for configure script regeneration
- build a tarball for external reproducibility
2020.81 - 29 October 2020
- Fix regression in 2020.79 which prevented connecting with some SSH
implementations. Increase MAX_PROPOSED_ALGO to 50, and print a log
message if the limit is hit. This fixes interoperability with sshj
library (used by PyCharm), and GoAnywhere.
Reported by Pirmin Walthert and Piotr Jurkiewicz
- Fix building with non-GCC compilers, reported by Kazuo Kuroi
- Fix potential long delay in dbclient, found by OSS Fuzz
- Fix null pointer dereference crash, found by OSS Fuzz
- libtommath now uses the same random source as Dropbear (in 2020.79
and 2020.80 used getrandom() separately)
- Some fuzzing improvements, start of a dbclient fuzzer
2020.80 - 26 June 2020
- Don't block authorized_keys logins with no-X11-forwarding or no-agent-forwarding
restrictions when X11 or agent forwarding are disabled at compile time.
This is more of a problem now X11 is disabled by default, reported by Guilhem Moulin
- Reduce binary size by 4kB (x64) when using bundled libtommath
- Define GNU_SOURCE for getrandom() on uclibc, reported by Laurent Bercot and
Fabrice Fontaine
- Improve checking libtomcrypt version compatibility
- Add some style notes to DEVELOPING.md
2020.79 - 15 June 2020
- Support ed25519 hostkeys and authorized_keys, many thanks to Vladislav Grishenko.
This also replaces curve25519 with a TweetNaCl implementation that reduces code size.
- Add chacha20-poly1305 authenticated cipher. This will perform faster than AES
on many platforms. Thanks to Vladislav Grishenko
- Support using rsa-sha2 signatures. No changes are needed to hostkeys/authorized_keys
entries, existing RSA keys can be used with the new signature format (signatures
are ephemeral within a session). Old ssh-rsa signatures will no longer
be supported by OpenSSH in future so upgrading is recommended.
- Use getrandom() call on Linux to ensure sufficient entropy has been gathered at startup.
Dropbear now avoids reading from the random source at startup, instead waiting until
the first connection. It is possible that some platforms were running without enough
entropy previously, those could potentially block at first boot generating host keys.
The dropbear "-R" option is one way to avoid that.
- Upgrade libtomcrypt to 1.18.2 and libtommath to 1.2.0, many thanks to Steffen Jaeckel for
updating Dropbear to use the current API. Dropbear's configure script will check
for sufficient system library versions, otherwise using the bundled versions.
- CBC ciphers, 3DES, hmac-sha1-96, and x11 forwarding are now disabled by default.
They can be set in localoptions.h if required.
Blowfish has been removed.
- Support AES GCM, patch from Vladislav Grishenko. This is disabled by default,
Dropbear doesn't currently use hardware accelerated AES.
- Added an API for specifying user public keys as an authorized_keys replacement.
See pubkeyapi.h for details, thanks to Fabrizio Bertocci
- Fix idle detection clashing with keepalives, thanks to jcmathews
- Include IP addresses in more early exit messages making it easier for fail2ban
processing. Patch from Kevin Darbyshire-Bryant
- scp fix for CVE-2018-20685 where a server could modify name of output files
- SSH_ORIGINAL_COMMAND is set for "dropbear -c" forced command too
- Fix writing key files on systems without hard links, from Matt Robinson
- Compatibility fixes for IRIX from Kazuo Kuroi
- Re-enable printing MOTD by default, was lost moving from options.h. Thanks to zciendor
- Call fsync() is called on parent directory when writing key files to ensure they are flushed
- Fix "make install" for manpages in out-of-tree builds, from Gabor Z. Papp
- Some notes are added in DEVELOPING.md
2019.78 - 27 March 2019
- Fix dbclient regression in 2019.77. After exiting the terminal would be left
in a bad state. Reported by Ryan Woodsmall
2019.77 - 23 March 2019
- Fix server -R option with ECDSA - only advertise one key size which will be accepted.
Reported by Peter Krefting, 2018.76 regression.
- Fix server regression in 2018.76 where multiple client -R forwards were all forwarded
to the first destination. Reported by Iddo Samet.
- Make failure delay more consistent to avoid revealing valid usernames, set server password
limit of 100 characters. Problem reported by usd responsible disclosure team
- Change handling of failed authentication to avoid disclosing valid usernames,
CVE-2018-15599.
- Fix dbclient to reliably return the exit code from the remote server.
Reported by W. Mike Petullo
- Fix export of 521-bit ECDSA keys, from Christian Hohnstädt
- Add -o Port=xxx option to work with sshfs, from xcko
- Merged fuzzing code, see FUZZER-NOTES.md
- Add a DROPBEAR_SVR_MULTIUSER=0 compile option to run on
single-user Linux kernels (CONFIG_MULTIUSER disabled). From Patrick Stewart
- Increase allowed username to 100 characters, reported by W. Mike Petullo
- Update config.sub and config.guess, should now work with RISC-V
- Cygwin compile fix from karel-m
- Don't require GNU sed (accidentally in 2018.76), reported by Samuel Hsu
- Fix for IRIX and writev(), reported by Kazuo Kuroi
- Other fixes and cleanups from François Perrad, Andre McCurdy, Konstantin Demin,
Michael Jones, Pawel Rapkiewicz
2018.76 - 27 February 2018
> > > Configuration/compatibility changes
IMPORTANT
Custom configuration is now specified in localoptions.h rather than options.h
Available options and defaults can be seen in default_options.h
To migrate your configuration, compare your customised options.h against the
upstream options.h from your relevant version. Any customised options should
be put in localoptions.h in the build directory.
- "configure --enable-static" should now be used instead of "make STATIC=1"
This will avoid 'hardened build' flags that conflict with static binaries
- Set 'hardened build' flags by default if supported by the compiler.
These can be disabled with configure --disable-harden if needed.
-Wl,-pie
-Wl,-z,now -Wl,-z,relro
-fstack-protector-strong
-D_FORTIFY_SOURCE=2
# spectre v2 mitigation
-mfunction-return=thunk
-mindirect-branch=thunk
Spectre patch from Loganaden Velvindron
- "dropbear -r" option for hostkeys no longer attempts to load the default
hostkey paths as well. If desired these can be specified manually.
Patch from CamVan Nguyen
- group1-sha1 key exchange is disabled in the server by default since
the fixed 1024-bit group may be susceptible to attacks
- twofish ciphers are now disabled in the default configuration
- Default generated ECDSA key size is now 256 (rather than 521)
for better interoperability
- Minimum RSA key length has been increased to 1024 bits
> > > Other features and fixes
- Add runtime -T max_auth_tries option from Kevin Darbyshire-Bryant
- Add 'dbclient -J &fd' to allow dbclient to connect over an existing socket.
See dbclient manpage for a socat example. Patch from Harald Becker
- Add "-c forced_command" option. Patch from Jeremy Kerr
- Restricted group -G option added with patch from stellarpower
- Support server-chosen TCP forwarding ports, patch from houseofkodai
- Allow choosing outgoing address for dbclient with -b [bind_address][:bind_port]
Patch from houseofkodai
- Makefile will now rebuild object files when header files are modified
- Add group14-256 and group16 key exchange options
- curve25519-sha256 also supported without @libssh.org suffix
- Update bundled libtomcrypt to 1.18.1, libtommath to 1.0.1
This fixes building with some recent versions of clang
- Set PAM_RHOST which is needed by modules such as pam_abl
- Improvements to DSS and RSA public key validation, found by OSS-Fuzz.
- Don't exit when an authorized_keys file has malformed entries. Found by OSS-Fuzz
- Fix null-pointer crash with malformed ECDSA or DSS keys. Found by OSS-Fuzz
- Numerous code cleanups and small issues fixed by Francois Perrad
- Test for pkt_sched.h rather than SO_PRIORITY which was problematic with some musl
platforms. Reported by Oliver Schneider and Andrew Bainbridge
- Fix some platform portability problems, from Ben Gardner
- Add EXEEXT filename suffix for building dropbearmulti, from William Foster
- Support --enable-<option> properly for configure, from Stefan Hauser
- configure have_openpty result can be cached, from Eric Bénard
- handle platforms that return close() < -1 on failure, from Marco Wenzel
- Build and configuration cleanups from Michael Witten
- Fix libtomcrypt/libtommath linking order, from Andre McCurdy
- Fix old Linux platforms that have SYS_clock_gettime but not CLOCK_MONOTONIC
- Update curve25519-donna implementation to current version
2017.75 - 18 May 2017
- Security: Fix double-free in server TCP listener cleanup
A double-free in the server could be triggered by an authenticated user if
dropbear is running with -a (Allow connections to forwarded ports from any host)
This could potentially allow arbitrary code execution as root by an authenticated user.
Affects versions 2013.56 to 2016.74. Thanks to Mark Shepard for reporting the crash.
CVE-2017-9078 https://hg.ucc.asn.au/dropbear/rev/c8114a48837c
- Security: Fix information disclosure with ~/.ssh/authorized_keys symlink.
Dropbear parsed authorized_keys as root, even if it were a symlink. The fix
is to switch to user permissions when opening authorized_keys
A user could symlink their ~/.ssh/authorized_keys to a root-owned file they
couldn't normally read. If they managed to get that file to contain valid
authorized_keys with command= options it might be possible to read other
contents of that file.
This information disclosure is to an already authenticated user.
Thanks to Jann Horn of Google Project Zero for reporting this.
CVE-2017-9079 https://hg.ucc.asn.au/dropbear/rev/0d889b068123
- Generate hostkeys with dropbearkey atomically and flush to disk with fsync
Thanks to Andrei Gherzan for a patch
- Fix out of tree builds with bundled libtom
Thanks to Henrik Nordström and Peter Krefting for patches.
2016.74 - 21 July 2016
- Security: Message printout was vulnerable to format string injection.
If specific usernames including "%" symbols can be created on a system
(validated by getpwnam()) then an attacker could run arbitrary code as root
when connecting to Dropbear server.
A dbclient user who can control username or host arguments could potentially
run arbitrary code as the dbclient user. This could be a problem if scripts
or webpages pass untrusted input to the dbclient program.
CVE-2016-7406
https://hg.ucc.asn.au/dropbear/rev/b66a483f3dcb
- Security: dropbearconvert import of OpenSSH keys could run arbitrary code as
the local dropbearconvert user when parsing malicious key files
CVE-2016-7407
https://hg.ucc.asn.au/dropbear/rev/34e6127ef02e
- Security: dbclient could run arbitrary code as the local dbclient user if
particular -m or -c arguments are provided. This could be an issue where
dbclient is used in scripts.
CVE-2016-7408
https://hg.ucc.asn.au/dropbear/rev/eed9376a4ad6
- Security: dbclient or dropbear server could expose process memory to the
running user if compiled with DEBUG_TRACE and running with -v
CVE-2016-7409
https://hg.ucc.asn.au/dropbear/rev/6a14b1f6dc04
The security issues were reported by an anonymous researcher working with
Beyond Security's SecuriTeam Secure Disclosure www.beyondsecurity.com/ssd.html
- Fix port forwarding failure when connecting to domains that have both
IPv4 and IPv6 addresses. The bug was introduced in 2015.68
- Fix 100% CPU use while waiting for rekey to complete. Thanks to Zhang Hui P
for the patch
2016.73 - 18 March 2016
- Support syslog in dbclient, option -o usesyslog=yes. Patch from Konstantin Tokarev
- Kill a proxycommand when dbclient exits, patch from Konstantin Tokarev
- Option to exit when a TCP forward fails, patch from Konstantin Tokarev
- New "-o" option parsing from Konstantin Tokarev. This allows handling some extra options
in the style of OpenSSH, though implementing all OpenSSH options is not planned.
- Fix crash when fallback initshells() is used, reported by Michael Nowak and Mike Tzou
- Allow specifying commands eg "dropbearmulti dbclient ..." instead of symlinks
- Various cleanups for issues found by a lint tool, patch from Francois Perrad
- Fix tab indent consistency, patch from Francois Perrad
- Fix issues found by cppcheck, reported by Mike Tzou
- Use system memset_s() or explicit_bzero() if available to clear memory. Also make
libtomcrypt/libtommath routines use that (or Dropbear's own m_burn()).
- Prevent scp failing when the local user doesn't exist. Based on patch from Michael Witten.
- Improved Travis CI test running, thanks to Mike Tzou
- Improve some code that was flagged by Coverity and Fortify Static Code Analyzer
2016.72 - 9 March 2016
- Validate X11 forwarding input. Could allow bypass of authorized_keys command= restrictions,
found by github.com/tintinweb. Thanks for Damien Miller for a patch. CVE-2016-3116
https://hg.ucc.asn.au/dropbear/rev/a3e8389e01ff
2015.71 - 3 December 2015
- Fix "bad buf_incrpos" when data is transferred, broke in 2015.69
- Fix crash on exit when -p address:port is used, broke in 2015.68, thanks to
Frank Stollenwerk for reporting and investigation
- Fix building with only ENABLE_CLI_REMOTETCPFWD given, patch from Konstantin Tokarev
- Fix bad configure script test which didn't work with dash shell, patch from Juergen Daubert,
broke in 2015.70
- Fix server race condition that could cause sessions to hang on exit,
https://github.com/robotframework/SSHLibrary/issues/128
2015.70 - 26 November 2015
- Fix server password authentication on Linux, broke in 2015.69
2015.69 - 25 November 2015
- Fix crash when forwarded TCP connections fail to connect (bug introduced in 2015.68)
- Avoid hang on session close when multiple sessions are started, affects Qt Creator
Patch from Andrzej Szombierski
- Reduce per-channel memory consumption in common case, increase default
channel limit from 100 to 1000 which should improve SOCKS forwarding for modern
webpages
- Handle multiple command line arguments in a single flag, thanks to Guilhem Moulin
- Manpage improvements from Guilhem Moulin
- Build fixes for Android from Mike Frysinger
- Don't display the MOTD when an explicit command is run from Guilhem Moulin
- Check curve25519 shared secret isn't zero
2015.68 - Saturday 8 August 2015
- Reduce local data copying for improved efficiency. Measured 30%
increase in throughput for connections to localhost
- Forwarded TCP ports connect asynchronously and try all available addresses
(IPv4, IPv6, round robin DNS)
- Fix all compile warnings, many patches from Gaël Portay
Note that configure with -Werror may not be successful on some platforms (OS X)
and some configuration options may still result in unused variable
warnings.
- Use TCP Fast Open on Linux if available. Saves a round trip at connection
to hosts that have previously been connected.
Needs a recent Linux kernel and possibly "sysctl -w net.ipv4.tcp_fastopen=3"
Client side is disabled by default pending further compatibility testing
with networks and systems.
- Increase maximum command length to 9000 bytes
- Free memory before exiting, patch from Thorsten Horstmann. Useful for
Dropbear ports to embedded systems and for checking memory leaks
with valgrind. Only partially implemented for dbclient.
This is disabled by default, enable with DROPBEAR_CLEANUP in sysoptions.h
- DROPBEAR_DEFAULT_CLI_AUTHKEY setting now always prepends home directory unless
there is a leading slash (~ isn't treated specially)
- Fix small ECC memory leaks
- Tighten validation of Diffie-Hellman parameters, from Florent Daigniere of
Matta Consulting. Odds of bad values are around 2**-512 -- improbable.
- Twofish-ctr cipher is supported though disabled by default
- Fix pre-authentication timeout when waiting for client SSH-2.0 banner, thanks
to CL Ouyang
- Fix null pointer crash with restrictions in authorized_keys without a command, patch from
Guilhem Moulin
- Ensure authentication timeout is handled while reading the initial banner,
thanks to CL Ouyang for finding it.
- Fix null pointer crash when handling bad ECC keys. Found by afl-fuzz
2015.67 - Wednesday 28 January 2015
- Call fsync() after generating private keys to ensure they aren't lost if a
reboot occurs. Thanks to Peter Korsgaard
- Disable non-delayed zlib compression by default on the server. Can be
enabled if required for old clients with DROPBEAR_SERVER_DELAY_ZLIB
- Default client key path ~/.ssh/id_dropbear
- Prefer stronger algorithms by default, from Fedor Brunner.
AES256 over 3DES
Diffie-hellman group14 over group1
- Add option to disable CBC ciphers.
- Disable twofish in default options.h
- Enable sha2 HMAC algorithms by default, the code was already required
for ECC key exchange. sha1 is the first preference still for performance.
- Fix installing dropbear.8 in a separate build directory, from Like Ma
- Allow configure to succeed if libtomcrypt/libtommath are missing, from Elan Ruusamäe
- Don't crash if ssh-agent provides an unknown type of key. From Catalin Patulea
- Minor bug fixes, a few issues found by Coverity scan
2014.66 - Thursday 23 October 2014
- Use the same keepalive handling behaviour as OpenSSH. This will work better
with some SSH implementations that have different behaviour with unknown
message types.
- Don't reply with SSH_MSG_UNIMPLEMENTED when we receive a reply to our own
keepalive message
- Set $SSH_CLIENT to keep bash happy, patch from Ryan Cleere
- Fix wtmp which broke since 2013.62, patch from Whoopie
2014.65 - Friday 8 August 2014
- Fix 2014.64 regression, server session hang on exit with scp (and probably
others), thanks to NiLuJe for tracking it down
- Fix 2014.64 regression, clock_gettime() error handling which broke on older
Linux kernels, reported by NiLuJe
- Fix 2014.64 regression, writev() could occassionally fail with EAGAIN which
wasn't caught
- Avoid error message when trying to set QoS on proxycommand or multihop pipes
- Use /usr/bin/xauth, thanks to Mike Frysinger
- Don't exit the client if the local user entry can't be found, thanks to iquaba
2014.64 - Sunday 27 July 2014
- Fix compiling with ECDSA and DSS disabled
- Don't exit abruptly if too many outgoing packets are queued for writev(). Patch
thanks to Ronny Meeus
- The -K keepalive option now behaves more like OpenSSH's "ServerAliveInterval".
If no response is received after 3 keepalives then the session is terminated. This
will close connections faster than waiting for a TCP timeout.
- Rework TCP priority setting. New settings are
if (connecting || ptys || x11) tos = LOWDELAY
else if (tcp_forwards) tos = 0
else tos = BULK
Thanks to Catalin Patulea for the suggestion.
- Improve handling of many concurrent new TCP forwarded connections, should now
be able to handle as many as MAX_CHANNELS. Thanks to Eduardo Silva for reporting
and investigating it.
- Make sure that exit messages from the client are printed, regression in 2013.57
- Use monotonic clock where available, timeouts won't be affected by system time
changes
- Add -V for version
2014.63 - Wednesday 19 February 2014
- Fix ~. to terminate a client interactive session after waking a laptop
from sleep.
- Changed port separator syntax again, now using host^port. This is because
IPv6 link-local addresses use %. Reported by Gui Iribarren
- Avoid constantly relinking dropbearmulti target, fix "make install"
for multi target, thanks to Mike Frysinger
- Avoid getting stuck in a loop writing huge key files, reported by Bruno
Thomsen
- Don't link dropbearkey or dropbearconvert to libz or libutil,
thanks to Nicolas Boos
- Fix linking -lcrypt on systems without /usr/lib, thanks to Nicolas Boos
- Avoid crash on exit due to cleaned up keys before last packets are sent,
debugged by Ronald Wahl
- Fix a race condition in rekeying where Dropbear would exit if it received a
still-in-flight packet after initiating rekeying. Reported by Oliver Metz.
This is a longstanding bug but is triggered more easily since 2013.57
- Fix README for ecdsa keys, from Catalin Patulea
- Ensure that generated RSA keys are always exactly the length
requested. Previously Dropbear always generated N+16 or N+15 bit keys.
Thanks to Unit 193
- Fix DROPBEAR_CLI_IMMEDIATE_AUTH mode which saves a network round trip if the
first public key succeeds. Still not enabled by default, needs more
compatibility testing with other implementations.
- Fix for port 0 forwarding in the client and port forwarding with Apache MINA SSHD. Thanks to
- Fix for bad system linux/pkt-sched.h header file with older Linux
kernels, from Steve Dover
- Fix signal handlers so that errno is saved, thanks to Erik Ahlén for a patch
and Mark Wickham for independently spotting the same problem.
2013.62 - Tuesday 3 December 2013
- Disable "interactive" QoS connection options when a connection doesn't
have a PTY (eg scp, rsync). Thanks to Catalin Patulea for the patch.
- Log when a hostkey is generated with -R, fix some bugs in handling server
hostkey commandline options
- Fix crash in Dropbearconvert and 521 bit key, reported by NiLuJe
- Update config.guess and config.sub again
2013.61test - Thursday 14 November 2013
- Default generated RSA key size changed from 1024 to 2048 bits
- ECC (elliptic curve) support. Supports ECDSA hostkeys (requires new keys to
be generated) and ECDH for setting up encryption keys (no intervention
required). This is significantly faster.
- [email protected] support for setting up encryption keys. This is
another elliptic curve mode with less potential of NSA interference in
algorithm parameters. curve25519-donna code thanks to Adam Langley
- -R option to automatically generate hostkeys. This is recommended for
embedded platforms since it allows the system random number device
/dev/urandom a longer startup time to generate a secure seed before the
hostkey is required.
- Compile fixes for old vendor compilers like Tru64 from Daniel Richard G.
- Make authorized_keys handling more robust, don't exit encountering
malformed lines. Thanks to Lorin Hochstein and Mark Stillwell
2013.60 - Wednesday 16 October 2013
- Fix "make install" so that it doesn't always install to /bin and /sbin
- Fix "make install MULTI=1", installing manpages failed
- Fix "make install" when scp is included since it has no manpage
- Make --disable-bundled-libtom work
2013.59 - Friday 4 October 2013
- Fix crash from -J command
Thanks to Lluís Batlle i Rossell and Arnaud Mouiche for patches
- Avoid reading too much from /proc/net/rt_cache since that causes
system slowness.
- Improve EOF handling for half-closed connections
Thanks to Catalin Patulea
- Send a banner message to report PAM error messages intended for the user
Patch from Martin Donnelly
- Limit the size of decompressed payloads, avoids memory exhaustion denial
of service
Thanks to Logan Lamb for reporting and investigating it. CVE-2013-4421
https://hg.ucc.asn.au/dropbear/rev/0bf76f54de6f
- Avoid disclosing existence of valid users through inconsistent delays
Thanks to Logan Lamb for reporting. CVE-2013-4434
https://hg.ucc.asn.au/dropbear/rev/d7784616409a
- Update config.guess and config.sub for newer architectures
- Avoid segfault in server for locked accounts
- "make install" now installs manpages
dropbearkey.8 has been renamed to dropbearkey.1
manpage added for dropbearconvert
- Get rid of one second delay when running non-interactive commands
2013.58 - Thursday 18 April 2013
- Fix building with Zlib disabled, thanks to Hans Harder and cuma@freetz
- Use % as a separator for ports, fixes scp in multihop mode, from Hans Harder
- Reject logins for other users when running as non-root, from Hans Harder
- Disable client immediate authentication request by default, it prevents
passwordless logins from working
2013.57 - Monday 15 April 2013
- Decreased connection setup time particularly with high latency connections,
the number of round trips has been reduced for both client and server.
CPU time hasn't been changed.
- Client will send an initial key exchange guess to save a round trip.
Dropbear implements an extension [email protected] to allow the first
packet guess to succeed in wider circumstances than the standard behaviour.
When communicating with other implementations the standard behaviour is used.
- Client side: when public key or password authentication with
$DROPBEAR_PASSWORD is used an initial authentication request will
be sent immediately rather than querying the list of available methods.
This behaviour is enabled by CLI_IMMEDIATE_AUTH option (on by default),
please let the Dropbear author know if it causes any interoperability
problems.
- Implement client escape characters ~. (terminate session) and
~^Z (background session)
- Server will more reliably clean up utmp when connection is closed, reported by
Mattias Walström