1.3.6 Release Notes ------------------------ This file contains a description of the major changes to ProFTPD for the 1.3.6 release cycle, from the 1.3.6rc1 release to the 1.3.6 maintenance releases. More information on these changes can be found in the NEWS and ChangeLog files. 1.3.6e --------- + Fixed null pointer deference in mod_sftp when using SCP incorrectly (Issue #1043). 1.3.6d --------- + Fixed issue with FTPS uploads of large files using TLSv1.3 (Issue #959). 1.3.6c --------- + Fixed regression in directory listing latency (Issue #863). + Detect OpenSSH-specific formatted SFTPHostKeys, and log hint for converting them to supported format. + Fixed use-after-free vulnerability during data transfers (Issue #903). + Fixed out-of-bounds read in mod_cap by updating the bundled libcap (Issue #902). 1.3.6b --------- + Fixed pre-authentication remote denial-of-service issue (Issue #846). + Backported fix for building mod_sql_mysql using MySQL 8 (Issue #824). 1.3.6a --------- + Fixed symlink navigation (Bug#4332). + Fixed building of mod_sftp using OpenSSL 1.1.x releases (Issue#674). + Fixed SITE COPY honoring of restrictions (Bug#4372). + Fixed segfault on login when using mod_sftp + mod_sftp_pam (Issue#656). + Fixed restarts when using mod_facl as a static module. 1.3.6 --------- + Support for using Redis for caching, logging; see the doc/howto/Redis.html documentation. + Fixed mod_sql_postgres SSL support (Issue #415). + Support building against LibreSSL instead of OpenSSL (Issue #361). + Better support on AIX for login restraictions (Bug #4285). + TimeoutLogin (and other timeouts) were not working properly for SFTP connections (Bug#4299). + Handling of the SIGILL and SIGINT signals, by the daemon process, now causes the child processes to be terminated as well (Issue #461). + RPM .spec file naming changed to conform to Fedora guidelines. + Fix for "AllowChrootSymlinks off" checking each component for symlinks (CVE-2017-7418). + New Modules: mod_redis, mod_tls_redis, mod_wrap2_redis With Redis now supported as a caching mechanism, similar to Memcache, there are now Redis-using modules: mod_redis (for configuring the Redis connection information), mod_tls_redis (for caching SSL sessions and OCSP information using Redis), and mod_wrap2_redis (for using ACLs stored in Redis). See the respective module documentation for details: doc/modules/mod_redis.html, doc/contrib/mod_tls_redis.html, and doc/contrib/mod_wrap2_redis.html. + Changed Modules: mod_ban The mod_ban module's BanCache directive can now use Redis-based caching; see doc/contrib/mod_ban.html#BanCache. + New Configuration Directives SQLPasswordArgon2, SQLPasswordScrypt The key lengths for Argon2 and Scrypt-based passwords are now configurable via these new directives; previously, the key length had been hardcoded to be 32 bytes, which is not interoperable with all other implementations (Issue #454). See doc/contrib/mod_sql_passwd.html#SQLPasswordArgon2, doc/contrib/mod_sql_passwd.html#SQLPasswordScrypt for details. + Changed Configuration Directives AllowChrootSymlinks When "AllowChrootSymlinks off" was used, only the last portion of the DefaultRoot path would be checked to see if it was a symlink. Now, each component of the DefaultRoot path will be checked to see if it is a symlink when "AllowChrootSymlinks off" is used. Include The Include directive can now be used within a section, e.g.: Include /path/to/allowed.txt DenyAll + API Changes A new JSON API has been added, for use by third-party modules. 1.3.6rc4 --------- + Fixed regression where all normal FTP users were handled as anonymous users. 1.3.6rc3 --------- + Support for OpenSSL 1.1.x API changes. + mod_sftp uses SHA256 for publickey fingerprints by default, rather than SHA1 or MD5. + mod_sql_passwd supports Scrypt and Argon2 password hashing algorithms when libsodium is detected in the header/library directories. + mod_sftp now supports extended attributes (xattrs) via SFTP. + Fixed bug in filesystem free space calculation causing ALLO to fail unexpectedly. + Default FTP/SSH2 banner changed to no longer include version information. + New -X command-line option for disabling forking, to aid debugging. + Logging of stacktraces now enabled by default; this also means that the installed executables do not have symbols stripped at install time. + Fixed memory leak when the mod_facl module is used. + Support for UNIX.ownername and UNIX.groupname MLSD/MLST facts. + Use initgroups(3) for group membership discovery by default, as it is faster/more performant on most systems. For the previous behavior, use the NoInitgroups AuthUnixOption. + Changed Modules: mod_ctrls_admin The mod_ctrls_admin module supports a new "config" ftpdctl action, which can be used to dynamically change configuration directives in the running daemon. See doc/contrib/mod_ctrls_admin.html#config for more details. + New Configuration Directives: CopyOptions The mod_copy module now supports a CopyOptions directive, for tweaking particular behaviors such as how to handle copy failures. See the documentation at doc/contrib/mod_copy.html#CopyOptions for details. DigestDefaultAlgorithm The mod_digest module uses the SHA1 algorithm for digests by default. Use the DigestDefaultAlgorithm to change this default as needed; see doc/contrib/mod_digest.html#DigestDefaultAlgorithm. FSOptions The --enable-xattr compile option enables support for extended attributes. There will be cases where this support needs to be disabled at runtime; use this option for doing so. See doc/modules/mod_core.html#FSOptions for more information. IncludeOptions The Include directive now supports wildcarded directory names. However, this behavior may not be desirable or have other consequences. Use the new IncludeOptions directive for altering this behavior, such as ignoring temporary files: IncludeOptions IgnoreTempFiles For other options, see the documentation at doc/modules/mod_core.html#IncludeOptions. MaxPasswordSize A denial-of-service attack can be mounted by causing excessive CPU usage via very long passwords processed via the crypt(3) function. To mitigate such resource consumption attacks, ProFTPD now imposes a maximum limit on the password length; that limit can be configured via this directive, documented at doc/modules/mod_auth.html#MaxPasswordSize. SFTPKeyLimits As cryptographic attacks grow more sophisticated, shorter keys become more at risk of compromise. The SFTPKeyLimits directive provides the administrator a way to set stronger policies by imposing a minimum key length for the various types of keys: RSA, DSA, ECC. For more information, see doc/contrib/mod_sftp.html#SFTPKeyLimits. SQLPasswordCost When libsodium support is detected by the build system, memory-hard algorithms such as scrypt and Argon2 are supported by the mod_sql_passwd module. These algorithms have tunable "costs"; the new SQLPasswordCost directive is for such tunings; see doc/contrib/mod_sql_passwd.html#SQLPasswordCost. + Changed Configuration Directives: AuthUnixOption ProFTPD will now try to use the initgroups(3) library function for group discovery by default. If this change of behavior leads to issues, the previous behavior can be restored using this new NoInitgroups AuthUnixOption. See doc/modules/mod_auth_unix.html#AuthUnixOptions for details. CapabilitiesEngine The CapabilitiesEngine directive of the mod_cap module was not being properly honored when used within or sections; this has now been fixed. FactsOptions The MLSD/MLST responses now include the UNIX.ownername and UNIX.groupname facts, for providing the textual labels. Some FTP clients may not handle these facts; use this new NoNames FactsOption value to have these new name facts not included in the MLSD/MLST responses by default. The documentation at doc/modules/mod_facts.html#FactsOptions contains more information. GeoIPAllowFilter, GeoIPDenyFilter The GeoIPAllowFilter and GeoIPDenyFilter directives of the mod_geoip module now support reading the filter data on a per-user basis, and support reading the filter data from SQL databases via a SQLNamedQuery. See the doc/contrib/mod_geoip.html#GeoIPAllowFilter documentation for details and examples. Include The Include directive now supported wildcarded directory names, e.g.: Include /path/to/sites/*/proftpd.conf Previously wildcards were only allowed as part of the filename. For more details, see doc/modules/mod_core.html#Include. ListOptions The mod_ls module returns file names for the NLST command in the order in which the names are provided by the underlying filesystem via the readdir(2) function. For many filesystems, the names are not ordered. However, some legacy FTP applications may assume/expect that the NLST names are orded. For such cases, use the new SortedNLST ListOption; see doc/modules/mod_ls.html#ListOptions. MasqueradeAddress The MasqueradeAddress directive is now allowed in sections, to ease configuration for name-based virtual hosts. SFTPKeyExchanges The mod_sftp module now supports the "curve25519-sha256@libssh.org" SSH key exchange algorithm, when compiled with the libsodium library. In addition, the following key exchange algorithms are supported: diffie-hellman-group14-sha256 diffie-hellman-group16-sha512 diffie-hellman-group18-sha512 SFTPOptions There are several new SFTPOptions supported: IgnoreFIFOs IgnoreSFTPSetExtendedAttributes IgnoreSFTPUploadExtendedAttributes The doc/contrib/mod_sftp.html#SFTPOptions documentation covers these new options in greater detail. + API Changes Many of the core API have been const-ified. This will cause build warnings in many existing third-party modules. 1.3.6rc2 --------- + SSH RSA hostkeys smaller than 2048 bits now work properly. + MLSD response lines are now properly CRLF terminated. + Faster/more efficient FTP ASCII mode conversion code. + Support for OCSP stapling. + Support for the common CLNT FTP command. + Fixed selection of DH groups from TLSDHParamFile. + New Modules: mod_auth_otp The mod_auth_otp module supports one-time passwords using the HOTP and TOTP algorithms. This OTP support is compatible with e.g. Google Authenticator and other implementations. The mod_auth_otp module can thus be used to provide multi-factor authentication (MFA, 2FA) for both FTP and SFTP logins. For more information, see the module documentation at doc/contrib/mod_auth_otp.html. mod_digest The mod_digest module implements the HASH FTP command, per the IETF Draft. This module also implements previous FTP commands that achieve similar functionality, e.g. XCRC, XMD5, XSHA1, and others. See the full module documentation at doc/contrib/mod_digest.html. mod_statcache Some sites often act as "mirrors", and/or have clients which perform numerous, repeated, and expensive directory listings. These directory listings cause repetitive (and often redundant) lookups of the per-file details via the stat(2) and lstat(2) system calls. The mod_statcache module caches this "stat" information, such that the cached data can be shared/reused across multiple FTP sessions. See doc/contrib/mod_statcache.html for details. + New Configuration Directives: AllowEmptyPasswords By default, proftpd allows for empty passwords to be used for authentication. Some sites may wish to enforce the requirement that passwords not be empty; this can now be accomplished via the AllowEmptyPasswords directive, e.g.: # Require non-empty passwords AllowEmptyPasswords on See doc/modules/mod_auth.html#AllowEmptyPasswords for details. Note that this applies to mod_sftp password-based logins as well. AnonAllowRobots Some web crawlers, notably Google, will automatically index any FTP sites with anonymous logins. This behavior is now automatically prohibited, using auto-generated robots.txt files for logins. Use the new AnonAllowRobots directive to allow indexing again; see doc/modules/mod_auth.html#AnonAllowRobots for details. SQLODBCVersion The mod_sql_odbc module defaults to using ODBC API version 3. However, some ODBC drivers may themselves expect older versions of the ODBC API. This can now be configured using e.g. "SQLODBCVersion ODBCv2"; see doc/contrib/mod_sql_odbc.html#SQLODBCVersion for more information. TLSSessionTickets The mod_tls module now supports TLS session tickets, per RFC 5077. See doc/contrib/mod_tls.html#TLSSessionTicketKeys for more details. TLSStapling The mod_tls module now supports OCSP stapling by caching OCSP responses for server certificates, and stapling those OCSP responses in the SSL/TLS handshake data. This OCSP stapling functionality is configuring using new directives: TLSStaplingCache TLSStaplingOptions TLSStaplingResponder TLSStaplingTimeout See the doc/contrib/mod_tls.html documentation for more information. + Changed Modules The mod_sftp module now supports the LINK_COUNT attribute in SFTP STAT requests, for clients using SFTP protocol version 6. It also supports the "hardlink@openssh.com" SFTP extension. The mod_tls_memcache and mod_tls_shmcache modules now provide OCSP responder caches. + Changed Configuration Directives: BanCacheOptions When storing ban rules in memcached, the mod_ban module can now format the rules as JSON, allowing for better interoperability with other applications interested in those ban rules. To use JSON, use "BanCacheOptions UseJSON"; see doc/contrib/mod_ban.html#BanCacheOptions for more information. BanOnEvent The mod_ban module can now be configured to ban clients which attempt to use empty passwords, when the new AllowEmptyPasswords directive is set to "false", via the new EmptyPassword BanOnEvent rule. See doc/contrib/mod_ban.html#BanOnEvent for more information. LogFormat The mod_log module supports several new LogFormat variables. The %R variable can be used for logging command response time, in milliseconds, which is useful for measuring response time/latency. Data transfer durations are separately tracked using the new %{transfer-millisecs} variable. For logging the size of the file after data transfer (e.g. after upload), use the %{file-size} variable. And for logging whether the file transfer used binary or ASCII mode, use the %{transfer-type} variable. MasqueradeAddress Sometimes the DNS name configured for MasqueradeAddress directives cannot be resolved when ProFTPD starts up, such as when the network interface on the host machine has not yet come up. This would cause ProFTPD to fail to start. The MasqueradeAddress directive now handles these resolution errors, and will attempt to resolve the DNS name later, when clients connect; this allows ProFTPD to start up properly in such cases. SFTPAuthMethods The mod_sftp module now supports requiring multiple authentication methods for a single login. Some sites, for example, wish for clients to authenticate via publickey AND password. This is supported via the SFTPAuthMethods directive, e.g.: # Require both publickey and password authentication, in any order SFTPAuthMethods publickey+password password+publickey The doc/contrib/mod_sftp.html#SFTPAuthMethods documentation has more information. SFTPExtensions The mod_sftp module now supports the "hardlink@openssh.com" SFTP extension. To disable support for this extension, use: SFTPExtensions -hardlink See doc/contrib/mod_sftp.html#SFTPExtensions for details. SQLConnectInfo, SQLNamedConnectInfo The mod_sql module can now support using SSL/TLS for connections to backend databases, if supported by the database-specific module, by configuring the necessary SSL/TLS details using the SQLConnectInfo and SQLNamedConnectInfo directives. See their respective documentation, doc/contrib/mod_sql.html#SQLConnectInfo and doc/contrib/mod_sql.html#SQLNamedConnectInfo for more information. TLSOptions The NoCertRequest TLSOption is now deprecated. The mod_tls module, rather than requesting client certificates every time, will only do so if "TLSVerifyClient on" or "TLSVerifyClient optional" is configured. This brings the mod_tls behavior more in line with Apache behavior, and slightly reduces the SSL/TLS handshake latency. TLSProtocol The mod_tls module now supports excluding of particular SSL/TLS versions via the TLSProtocol directive, e.g.: # Support all TLS versions except SSLv3 TLSProtocol ALL -SSLv3 The doc/contrib/mod_tls.html#TLSProtocol documentation has more details. TLSSessionCache When storing SSL session data in memcached, the mod_tls module can now format the session data using JSON, allowing for better interoperability with other applications interested in that session data. To use JSON, use "TLSSessionCache memcache:/json". See doc/contrib/mod_tls_memcache.html for more information. UseEncoding Different users/clients may wish to use different filename encodings for their files. The UseEncoding directive can now be set per-user/group/class, by now working with mod_ifsession sections as expected. 1.3.6rc1 --------- + Support the HOST command (see RFC 7151). + Changed the default SyslogLevel to be NOTICE, rather than DEBUG. + Fixed "stalled" SSL/TLS handshakes for data transfers. + ftpwho now supports JSON output format. + Fixed handling of SSH keys with overlong Comment headers in mod_sftp_sql. + Changed handling of logging of SFTP sessions to ExtendedLogs; see the notes below on the ExtendedLog directive. + Changed Modules mod_facl The mod_facl module now supports the MacOSX flavour of POSIX ACLs. mod_radius The mod_radius module has added support for the following RADIUS attributes: Acct-Terminate-Cause Event-Timestamp Idle-Timeout Message-Authenticator Reply-Message Session-Timeout mod_site_misc The SITE UTIME command now supports the 3-timestamp variant: SITE UTIME path atime mtime ctime where each timestamp is expressed as "YYYYMMDDhhmmss". mod_sql The mod_sql module would previously only support 32-bit UID/GID values, due to its use of the atoi(3) C library function for parsing result set values into IDs. This has been fixed; mod_sql now properly supports 64-bit UID/GID values. mod_tls By default, mod_tls will no longer support SSLv3 connections. In order to support SSLv3 connections (for sites that need to), you must explicitly configure this via the TLSProtocol directive, e.g.: TLSProtocol SSLv3 TLSv1 ... In addition, mod_tls will no longer support EXPORT ciphers. + New Configuration Directives: CopyEngine The mod_copy module is enabled by default; there may be cases where the module should be disabled, without requiring a rebuild of the server. Thus mod_copy now supports a CopyEngine directive; see doc/contrib/mod_copy.html#CopyEngine. DelayOnEvent There are sites which wish to use mod_delay for administratively adding delays to connections as e.g. brute force attack deterrents. To support these use cases, the mod_delay module has a new DelayOnEvent directive. Using this directive, sites can configure something like the following, for forcing a minimum login delay and a failed login delay: # Configure successful logins to be delayed by 2 secs DelayOnEvent PASS 2000ms # Configure failed logins to be delayed by 5 secs DelayOnEvent FailedLogin 5s See doc/modules/mod_delay.html#DelayOnEvent for more information. ExecEnable Some sites using mod_exec need to configure a command to be executed, but wish to "blacklist" certain directories where that command should not be executed. To handle configurations like this, the mod_exec module has a new ExecEnable directive; see doc/contrib/mod_exec.html#ExecEnable for details. FSCachePolicy ProFTPD has long maintained a cache of the last stat data for a file. However, for performance reasons, this cache size needs to be larger, and to be enhanced to handle expiration, etc. To tune the size and expiration settings of this filesystem data cache, use the new FSCachePolicy directive; see doc/modules/mod_core.html#FSCachePolicy for details. LangOptions Currently proftpd tries to cope with various filename/character encodings used by FTP clients; if it cannot decode the filename, it will use the sent filename as-is. This behavior can cause problems for downstream resources that then attempt to deal with these filenames, and fail. To make proftpd be more strict about the encoding it accepts, use the new LangOption directive: LangOptions RequireValidEncoding See doc/modules/mod_lang.html#LangOptions. RadiusOptions The mod_radius module now supports/handles additional RADIUS attributes. Some of these attribute may need to be ignore for some sites; others may wish to e.g. enforce stronger security by requiring the use of the Message-Authenticator attribute. Thus mod_radius has a new RadiusOptions directive; see doc/contrib/mod_radius.html#RadiusOptions for details. ServerAlias Supporting true name-based virtual hosting means needing to associate names with the IP-based virtual hosts. The ServerAlias directive is used to do this association; see doc/modules/mod_core.html#ServerAlias for details. SQLPasswordSaltEncoding In order to handle binary data for salts, the mod_sql_password module now supports handling of this data as base64- or hex-encoded data via the new SQLPasswordSaltEncoding directive; see doc/contrib/mod_sql_passwd.html#SQLPasswordSaltEncoding for details. TLSECDHCurve When an FTPS client uses an ECDHE cipher, mod_tls currently will use the X9.62 prime256v1 curve. Some sites may, however, wish to use other curves for ECDHE ciphers. These sites may now use the new TLSECDHCurve directive to configure the curve; see doc/contrib/mod_tls.html#TLSECDHCurve for details. TLSNextProtocol Newer TLS clients use the ALPN (Application Layer Protocol Negotiation) extension (or its earlier incarnation NPN (Next Protocol Negotiation) for determining the protocol that will be used over the SSL/TLS session. The support for these extensions can be used by clients for enabling other behaviors/optimizations, such as TLS False Start. This directive can be used to disable mod_tls' use of the ALPN/NPN extensions as needed; see doc/contrib/mod_tls.html#TLSNextProtocol for more details. TLSPreSharedKey Some sites may find that using pre-shared keys (PSK) is preferable for their TLS needs. TLS clients in embedded or low power environments may find PSK to be less computationally expensive. The mod_tls module now supports pre-shared keys via its TLSPreSharedKey directive; see doc/contrib/mod_tls.html#TLSPreSharedKey for details. TransferOptions There are some broken (e.g. old/mainframe) FTP clients that will upload files, containing CRLF sequences, as ASCII data, but these clients expect these CRLF sequences to be left as-is by the FTP server. To handle these broken clients, there is a new TransferOptions directive; see doc/modules/mod_xfer.html#TransferOptions for more information. + Changed Configuration Directives BanOnEvent BadProtocol Some clients (malicious or unintentional) may send HTTP or SMTP commands to ProFTPD. ProFTPD now detects these "bad protocol" messages, and mod_ban can now ban clients that repeatedly do this via its BanOnEvent rules. See doc/contrib/mod_ban.html#BanOnEvent for details. DelayTable none If the mod_delay module is used to enforce minimum delays, and not use its DelayTable for "learning" the best delay, then the DelayTable is not needed/used to all. The DelayTable directive can now be used to tell mod_delay to not even open/lock on that table, using: DelayTable none See doc/modules/mod_delay.html#DelayTable. DeleteAbortedStores The DeleteAbortedStores directive, for Bug#3917, was meant to be enabled, but only when HiddenStores was in effect. Unfortunately, the fix caused a regression, as DeleteAbortedStores was enabled for ALL transfers inadvertently. The desired behavior, of enabling DeleteAbortedStores only when HiddenStores is in effect, has been properly implemented now. ExtendedLog When an ExtendedLog is used for logging mod_sftp requests, the log file will contain both the SFTP requests AND the internal FTP commands to which mod_sftp will map the SFTP requests; this can lead to some VERY verbose log files. For greater control over SFTP logging, the ExtendedLog directive now supports two new log classes: SSH, and SFTP. In addition, it supports the '!' prefix, for excluding certain log classes from a given ExtendedLog. For example: LogFormat ftp "..." ALL,EXIT,!SSH,!SFTP ExtendedLog /path/to/extended-ftp.log ftp LogFormat sftp "..." SSH,SFTP ExtendedLog /path/to/extended-sftp.log sftp NOTE that existing ExtendedLogs that expect to see the SFTP requests will no longer do so; adding the "SFTP" logging class to such ExtendedLogs is now necessary. HiddenStores Some sites may experience HiddenStores filename collisions when uploading FTP clients get disconnected, and/or use multiple concurrent sessions for uploading. To help avoid collisions, the HiddenStores directive now supports the %P variable, for adding the session PID to the generated HiddenStore name. In other cases, some sites may have FTP clients that want to use the APPE FTP command, but cannot do so when HiddenStores is in effect. These FTP clients are often outside of the site's control, and not easily changed. ProFTPD now automatically disables the HiddenStores functionality when an APPE FTP command is used; the APPE command can only function on an existing file anyway, and thus there is no loss of functionality with this policy change. ListOptions When ProFTPD generates a directory listing for FTP commands such as LIST or NLST, it will automatically sort the names lexicographically. For very wide directories, this can cause more memory/CPU usage, in order to sort all of these names. This sorting can now be disabled via ListOptions, using: ListOptions -U See doc/modules/mod_ls.html#ListOptions for more information. SFTPDigests The mod_sftp module now supports the umac-128@openssh.com MAC algorithm; see doc/contrib/mod_sftp.html#SFTPDigests. SFTPHostKey Large hosting sites often use a section for centralizing configuration of a large number of sections in their proftpd.conf. Sometimes, such sites will want to disable use of particular SSH hostkeys for a given . To support this use case, the SFTPHostKey directive can be used to ignore any globally-configured RSA, DSA, or ECDSA SSH hostkey, e.g.: SFTPHostKey NoRSA SFTPHostKey NoDSA See doc/contrib/mod_sftp.html#SFTPHostKey for details. SFTPOptions Some OS distributions insist that their SSH hostkeys be group-readable. In order to allow mod_sftp, which has more strict SSH hostkey permission policies, to use those SSH hostkeys, the SFTPOptions directive can now be used to relax this permission policy as needed: SFTPOptions InsecureHostKeyPerms See doc/contrib/mod_sftp.html#SFTPOptions for details. Small Diffie-Hellman groups are subject to cryptographic weaknesses; see https://weakdh.org. Thus mod_sftp now avoids the use of weak DH groups by default; the AllowWeakDH SFTPOption is used to re-enable such support for clients that require it. See doc/contrib/mod_sftp.html#SFTPOptions. SNMPAgent Some sites may wish to have mod_snmp listening on multiple addresses (e.g. on multi-homed servers), including IPv6 addresses. The SNMPAgent directive now supports this, e.g.: SNMPAgent master 127.0.0.1:1161 10.0.1.2:1161 [::] See doc/contrib/mod_snmp.html#SNMPAgent for more information. TLSOptions Small Diffie-Hellman groups are subject to cryptographic weaknesses; see https://weakdh.org. Thus mod_tls now avoids the use of weak DH groups by default; the AllowWeakDH TLSOption is used to re-enable such support for clients that require it. See doc/contrib/mod_tls.html#TLSOptions. + Changed Command Handling When handling the STAT FTP command, ProFTPD now follows RFC 959 more closely, and will use the 213 response code for STAT commands on files, and the 212 response code for STAT commands on directories. Previously, ProFTPD would respond to all STAT commands using the 211 response code. + Changed Utilities The ftpwho command-line utility can now emit its data as JSON, for easier parsing/reuse in other utilities. To request JSON, use: $ ftpwho -o json