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

📋 NAME

sftp-server — OpenSSH SFTP server subsystem

🚀 Quick Reference

Use Case	Command	Description
🔧 Start SFTP subsystem	/usr/libexec/sftp-server	Default invocation via sshd Subsystem
🐛 Debug logging	sftp-server -e -l DEBUG	Log to stderr with debug level
🏷️ Set log facility	sftp-server -f LOCAL0	Use a specific syslog facility
📂 Starting directory	sftp-server -d /chroot/%u	Alternate start directory with token expansion
🔒 Read-only mode	sftp-server -R	Deny all write operations
🚫 Deny specific requests	sftp-server -P write,rename	Block certain SFTP protocol requests
✅ Allow only specific requests	sftp-server -p read,open,close	Permit only a subset of requests
❓ Query supported requests	sftp-server -Q requests	List all request types for allow/deny lists
🔢 Set umask	sftp-server -u 022	Override default umask for new files

🖥️ 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.

🔧 Options

• -d start_directory — 📁 Specifies an alternate starting directory for users. The pathname may contain the following tokens that are expanded at run-time: %% 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 AT openbsd.org>

📘 SFTP-SERVER(8) — BSD System Manager's Manual SFTP-SERVER(8) 📋 NAME 🚀 Quick Reference 🖥️ SYNOPSIS 📖 DESCRIPTION 📚 SEE ALSO 📜 HISTORY ✍️ AUTHORS