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 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>

July 27 2021 | NetBSD 10.0