UFTPD(8) System Manager's Manual UFTPD(8)

No nonsense TFTP/FTP Server

uftpd [
] [
-l LOG
] [
-o ftp=PORT,tftp=PORT,writable
] [
] [

uftpd is a very simple TFTP and anonymous FTP server with inetd support. It listens on standard Internet ports for each protocol, as defined in the system service specification, /etc/services, unless other ports are given on the command line. For details, see services(5).
Without any command line arguments uftpd serves both FTP and TFTP and automatically backgrounds itself. Usually uftpd this means listen to port 21 (FTP) and port 69 (TFTP), serve files from /srv/ftp, and log to syslog. Messages are written to the syslog using the LOG_FTP facility.
Available command line options:
Show built-in help text
Set log level: none, err, notice, info, debug. By default the log level is notice, which is less verbose than info, but still logs all relevant events: users logging in, uploading, downloading, creating and removing directories, etc. To reduce the log level, start uftpd with -l error.
Run in foreground, do not detach from controlling terminal
Set uftpd option, separate multiple options with comma:
Override Internet ports otherwise derived from services(5). Set the PORT to zero (0) to disable a service.
The writable option enables writable FTP root, which is not recommended. Some people want this, but it is recommended to instead rely on a writable sub-directory, like upload/, or similar.
An address passed to the client in passive mode can be overridden with the pasv_addr option (real data socket address remains unchanged). This may be useful for passing through some types of NAT.
File to store process ID for signaling uftpd. The default depends on how uftpd was configured at build time, and also the UNIX system it runs on, but often it is found in /var/run/uftpd.pid.
Use syslog, even if running in foreground, default when running in the background
Show program version
Root directory. The default is to serve files from the FTP user's $HOME. When started as root uftpd will chroot to this directory as a security measure.

uftpd can also be used with an Internet superserver, like the traditional inetd or modern init replacements like finit. In inetd mode the server takes client connections from stdin. To enable inetd mode uftpd must be called as either in.tftpd or in.ftpd. In inetd mode uftpd always runs in the foreground with syslog for messages.

The file /etc/nologin can be used to disable FTP access. If the file exists, uftpd displays it and exits. If the file /etc/ftpwelcome exists, uftpd prints it before issuing the “ready” message. If the file /etc/motd exists, uftpd prints it after a successful login. If the file .message exists in a directory, uftpd prints it when that directory is entered.
The FTP server currently supports the following requests. The case of the requests is ignored.
Request Description
ABOR abort current transfer
CDUP shorthand for CD .. command
CWD change working directory
CLNT accepted and ignored by server
DELE delete a file
EPRT RFC 2428, extended PORT command
EPSV extended PASV command, used by VLC for Android
FEAT list supported features
HELP show help text
LIST give list files in a directory (“ls -lgA”)
MDTM RFC 3659, return the last-modified time of a file
MLST RFC 3659 extension to LIST
MLSD RFC 3659 extension to LIST
MKD make a directory
NLST like LIST, but much less verbose
NOOP do nothing, used for keep-alive
PASS specify password
PASV prepare for server-to-server transfer
PORT specify data connection port
PWD print the current working directory
QUIT terminate session
REST restore RETR or STOR command at file offset
RETR retrieve a file
RMD remove a directory
RNFR specify rename-from file name
RNTO specify rename-to file name
SIZE return size of file
STOR store a file
SYST show operating system type of server system
TYPE specify data transfer type
USER specify user name
Remaining FTP requests, as specified in Internet RFC959, are not recognized at the moment. Patches are welcome!

uftpd also supports TFTP, the Trivial File Transfer Protocol, which is often used for net booting diskless devices, e.g., BOOTP and PXEBOOT.
The TFTP server currently supports the following requests.
Request Description
RRQ Read Request for file, may have options
WRQ Write Request for file, may have options
DATA File data, preceded by block n:o
ERROR Error, end of session
ACK ACKnowledge DATA or WRQ without options
OACK Option acknowledged, sent as response to RRQ/WRQ
uftpd supports TFTP blocksize negotiation, according to RFC2348, so full sized Ethernet frames can be used, which greatly speeds up transfers.

FTP Welcome notice.
Message of the day, presented after successful FTP login.
Displayed to user attempting to connect. Access is refused if this file exists.
Program default PID file, created only when uftpd is ready with its internal setup and able to service signals. Note, uftpd exits on most signals. So no special processing is done atm.

ftp(1), tftp(1), syslogd(8)

uftpd was written by Joachim Wiberg ⟨mailto:troglobit@gmail.com⟩ and is maintained at ⟨https://github.com/troglobit/uftpd⟩

Here be dragons.
December 6, 2021 uftpd (2.14)