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SFTP-SERVER(8)            BSD System Manager's Manual           SFTP-SERVER(8)

NAME
     sftp-server — OpenSSH SFTP server subsystem

SYNOPSIS
     sftp-server [-ehR] [-d start_directory] [-f log_facility] [-l log_level] [-P denied_requests]
                 [-p allowed_requests] [-u umask]
     sftp-server -Q protocol_feature

DESCRIPTION
     sftp-server is a program that speaks the server side of SFTP protocol to stdout and expects
     client requests from stdin.  sftp-server is not intended to be called directly, but from
     sshd(8) using the Subsystem option.

     Command-line flags to sftp-server should be specified in the Subsystem declaration.  See
     sshd_config(5) for more information.

     Valid options are:

     -d start_directory
             Specifies an alternate starting directory for users.  The pathname may contain the fol‐
             lowing tokens that are expanded at runtime: %% is replaced by a literal '%', %d is re‐
             placed by the home directory of the user being authenticated, and %u is replaced by the
             username of that user.  The default is to use the user's home directory.  This option
             is useful in conjunction with the sshd_config(5) ChrootDirectory option.

     -e      Causes sftp-server to print logging information to stderr instead of syslog for debug‐
             ging.

     -f log_facility
             Specifies the facility code that is used when logging messages from sftp-server.  The
             possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2, LOCAL3, LOCAL4, LO‐
             CAL5, LOCAL6, LOCAL7.  The default is AUTH.

     -h      Displays sftp-server usage information.

     -l log_level
             Specifies which messages will be logged by sftp-server.  The possible values are:
             QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3.  INFO and VER‐
             BOSE log transactions that sftp-server performs on behalf of the client.  DEBUG and DE‐
             BUG1 are equivalent.  DEBUG2 and DEBUG3 each specify higher levels of debugging output.
             The default is ERROR.

     -P denied_requests
             Specifies a comma-separated list of SFTP protocol requests that are banned by the
             server.  sftp-server will reply to any denied request with a failure.  The -Q flag can
             be used to determine the supported request types.  If both denied and allowed lists are
             specified, then the denied list is applied before the allowed list.

     -p allowed_requests
             Specifies a comma-separated list of SFTP protocol requests that are permitted by the
             server.  All request types that are not on the allowed list will be logged and replied
             to with a failure message.

             Care must be taken when using this feature to ensure that requests made implicitly by
             SFTP clients are permitted.

     -Q protocol_feature
             Queries protocol features supported by sftp-server.  At present the only feature that
             may be queried is “requests”, which may be used to deny or allow specific requests
             (flags -P and -p respectively).

     -R      Places this instance of sftp-server into a read-only mode.  Attempts to open files for
             writing, as well as other operations that change the state of the filesystem, will be
             denied.

     -u umask
             Sets an explicit umask(2) to be applied to newly-created files and directories, instead
             of the user's default mask.

     On some systems, sftp-server must be able to access /dev/log for logging to work, and use of
     sftp-server in a chroot configuration therefore requires that syslogd(8) establish a logging
     socket inside the chroot directory.

SEE ALSO
     sftp(1), ssh(1), sshd_config(5), sshd(8)

     T. Ylonen and S. Lehtinen, SSH File Transfer Protocol, draft-ietf-secsh-filexfer-02.txt,
     October 2001, work in progress material.

HISTORY
     sftp-server first appeared in OpenBSD 2.8.

AUTHORS
     Markus Friedl <markus AT openbsd.org>

BSD                              July 27, 2021                             BSD