No Nonsense FTP/TFTP Server

uftpd is a UNIX daemon with sane built-in defaults. It just works.

Features

• FTP and/or TFTP
• No complex configuration file
• Runs from standard UNIX inetd, or standalone
• Uses ftp user's $HOME, from /etc/passwd, or custom path
• Uses ftp/tcp and tftp/udp from /etc/services, or custom ports
• Privilege separation, drops root privileges having bound to ports
• Possible to use symlinks outside of the FTP home directory
• Possible to have group writable FTP home directory

Usage

uftpd [-hnsv] [-l LEVEL] [-o OPTS] [PATH]

  -h         Show this help text
  -l LEVEL   Set log level: none, err, notice (default), info, debug
  -n         Run in foreground, do not detach from controlling terminal
  -o OPT     Options:
                      ftp=PORT
                      tftp=PORT
                      pasv_addr=ADDR
                      writable
  -s         Use syslog, even if running in foreground, default w/o -n
  -v         Show program version

The optional 'PATH' defaults to the $HOME of the /etc/passwd user 'ftp'
Bug report address: https://github.com/troglobit/uftpd/issues

To start uftpd in the background as an FTP/TFTP server:

uftpd

If the ftp user does not exist on your system, uftpd defaults to serve files from the /srv/ftp directory. To serve another directory, simply append that directory to the argument list.

Use sudo, or set CAP_NET_BIND_SERVICE capabilities, on uftpd to allow regular users to start uftpd on privileged (standard) ports, i.e. < 1024:

sudo setcap cap_net_bind_service+ep uftpd

To change port on either FTP or TFTP, use:

uftpd -o ftp=PORT,tftp=PORT

Set PORT to zero (0) to disable either service.

New sessions are droppbed by default if uftpd detects the FTP root is writable. To allow writable FTP root:

uftpd -o writable PATH

Note: since v2.11 uftpd logs a lot more events by default. Set up your syslogd to redirect LOG_FTP to a separate log file, or reduce the log level of uftpd using -l error to only log errors and higher.

Running from inetd

Rarely used services like FTP/TFTP are good candidates to run from the Internet super server, inetd. On Debian and Ubuntu based distributions we recommend openbsd-inetd.

Use the following two lines in /etc/inetd.conf, notice how in.ftpd and in.tftpd are symlinks to the uftpd binary:

ftp     stream  tcp nowait  root    /usr/sbin/in.ftpd
tftp    dgram   udp wait    root    /usr/sbin/in.tftpd

Remember to activate your changes to inetd by reloading the service or sending SIGHUP to it. Another inetd server may use different syntax. Like the inetd that comes built-in to Finit, in /etc/finit.conf:

inetd ftp/tcp   nowait /usr/sbin/in.ftpd  -- The uftpd FTP server
inetd tftp/udp    wait /usr/sbin/in.tfptd -- The uftpd TFTP server

Caveat

uftpd is primarily not targeted at secure installations, it is targeted at users in need of a simple FTP/TFTP server.

uftpd allows symlinks outside the FTP root, as well as a group writable FTP home directory — user-friendly features that potentially can cause security breaches, but also very useful for people who just want their FTP server to work. A lot of care has been taken, however, to lock down and secure uftpd by default.

Build & Install

Debian/Ubuntu

curl -sS https://deb.troglobit.com/pubkey.gpg | sudo apt-key add -
echo "deb [arch=amd64] https://deb.troglobit.com/debian stable main" | sudo tee /etc/apt/sources.list.d/troglobit.list
sudo apt-get update && sudo apt-get install uftpd

Building from Source

uftpd depends on two other projects to build from source, libuEv and lite. See their respective README for details, there should be no real surprises, both use the familiar configure, make, make install.

To find the two libraries uftpd depends on pkg-config. The package name for your Linux distribution varies, on Debian/Ubuntu systems:

user@example:~/> sudo apt install pkg-config

uftpd, as well as its dependencies, can be built as .deb packages on Debian or Ubuntu based distributions. Download and install each of the dependencies, and then run

./autogen.sh      <--- Only needed if using GIT sources
./configure
make package

The .deb package takes care of setting up /etc/inetd.conf, create an ftp user and an /srv/ftp home directory with write permissions for all members of the users group.

If you are using a different Linux or UNIX distribution, check the output from ./configure --help, followed by make all install. For instance, building on Alpine Linux:

PKG_CONFIG_LIBDIR=/usr/local/lib/pkgconfig ./configure \
    --prefix=/usr --localstatedir=/var --sysconfdir=/etc

Provided the library dependencies were installed in /usr/local/. This PKG_CONFIG_LIBDIR trick may be needed on other GNU/Linux, or UNIX, distributions as well.

Origin & References

uftpd was originally based on FtpServer by Xu Wang, but is now a complete rewrite with TFTP support by Joachim Wiberg, maintained at GitHub.