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-