SFTP-SERVER(8) Maintenance Commands and Procedures 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 debugging.

-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, LOCAL5, 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 VERBOSE 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, 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@openbsd.org>

illumos July 27, 2021 illumos