man > SFTP-SERVER(8)

SFTP-SERVER(8)                         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
               following tokens that are expanded at runtime: %% is replaced by a literal '%', %d is
               replaced 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  de‐
               bugging.

       -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
               DEBUG1 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, in‐
               stead 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>

Debian                                      July 27, 2021                             SFTP-SERVER(8)