2.5.1. Overview¶

For macOS systems, SFTPPlus is distributed as a gzipped TAR archive. Installing SFTPPlus consists of unpacking the archive, initializing the configuration, and generating the SSH keys and the SSL key and certificate to be used by the product.

The included default configuration requires the creation of a system account, usually named sftpplus, under which the SFTPPlus process is executed. This is a special type of OS user also known as a service account.

Optionally, you may choose to start SFTPPlus as root, but the service account is still required in order to drop privileges after starting up.

This dedicated OS user should not be used in any other way, doesn't require a password to be set for it, and should not be available through SFTPPlus services even if authenticating operating system users is enabled.

To have SFTPPlus launched at boot, you may use the included plist file.

All steps beyond unpacking the archive can be handled by the shell script found at ./bin/install.sh in the hierarchy of SFTPPlus files.

2.5.2. Unpacking the archive¶

After downloading the compressed archive, you can extract its files using the following command:

tar xfz sftpplus-os-arch-version.tar.gz

To install SFTPPlus, move (or copy/link) the unpacked directory to your preferred installation path, for example: /Library/sftpplus.

SFTPPlus may be installed in any location on the local file system. In this documentation page we assume that SFTPPlus is unpacked in the /Library/sftpplus directory (we discuss INSTALL_ROOT more later). Avoid using spaces or special characters in the SFTPPlus installation path.

2.5.3. Shell script installer¶

The easiest way to install SFTPPlus is to execute the shell script found at ./bin/install.sh in the hierarchy of SFTPPlus files, for example:

sudo /Library/sftpplus/bin/install.sh

The install.sh script will guide you through all the necessary steps.

Once the installation is complemented, the install script will automatically start the SFTPPlus process. You can check the status of the SFTPPus process using:

launchctl list | grep SFTPPlus

After a successful installation using the shell script, jump to Listening on privileged ports to learn how to enable SFTPPlus to listen on privileged ports. This would be needed if SFTPPlus is not started with superuser privileges, which would mean it cannot bind ports below 1024.

2.5.4. Initializing the configuration¶

When installing SFTPPlus on a machine for the first time, you need to generate the initial configuration file and machine-specific SSH keys. A self-signed SSL certificate will also be generated to help with the initial FTPS and HTTPS testing.

To initialize a fresh SFTPPlus installation, execute the following command (where $ADMIN should be replaced with your favourite administrative username and $PASS with a password to be used for the SFTPPlus $ADMIN user):

cd /Library/sftpplus
./bin/admin-commands.sh initialize --init-admin $ADMIN --init-password $PASS

Default configuration allows external connections to the management web page. Therefore, use a secure password to protect the management web page.

./bin/admin-commands.sh initialize \
    --local-admin-access \
    --init-admin $ADMIN \
    --init-password $PASS

The initialization step is not required when upgrading SFTPPlus. It will not overwrite the configuration file, SSH keys, and SSL keys and certificates, if existing. In the case that you want to generate a new configuration, manually remove the existing files first.

2.5.5. Configuring the SFTPPlus process user and group¶

On macOS, the SFTPPlus processes are managed by launchd.

The following are details for configuring the SFTPPlus account and group for macOS systems.

# Create the group dedicated to the service account.
sudo dscl . create /Groups/sftpplus
# Assign an unique ID to the group.
sudo dscl . create /Groups/sftpplus PrimaryGroupID 299
# Disable group password.
sudo dscl . create /Groups/sftpplus Password '*'
# Create a user for the service account.
sudo dscl . create /Users/sftpplus
# Assign a unique ID to the new user.
sudo dscl . create /Users/sftpplus UniqueID 299
# Assign this account to the dedicated group.
sudo dscl . create /Users/sftpplus PrimaryGroupID 299
# Disable shell access.
sudo dscl . create /Users/sftpplus UserShell /usr/bin/false
# Make sure it has a default empty home folder.
sudo dscl . create /Users/sftpplus NFSHomeDirectory /var/empty
# Disable password to block any authentication request.
sudo dscl . create /Users/sftpplus Password '*'
# Initialize blank password and authentication rules.
sudo dscl . delete /Users/sftpplus PasswordPolicyOption
sudo dscl . delete /Users/sftpplus AuthenticationAuthority

cd /Library && chown -R root:admin sftpplus
cd /Library/sftpplus && chown -R sftpplus configuration/ log/ run/

2.5.6. Launchd system configuration¶

The next step is to configure your operating system to automatically start SFTPPlus on boot.

SFTPPlus is designed to be started via the macOS launchd system tool as a daemon that runs continuously.

For macOS systems, you can use the example launchd job definition provided with SFTPPlus. The job definition file is formatted as XML, and it is called a property list file or 'plist'. Edit this file with your favourite editor, e.g. vi:

vi bin/sftpplus-mft.plist

Depending on where the job definition is copied onto your system, it will be treated as a service or an agent. In order to have SFTPPlus act as a global service, launching each time the macOS system starts, you need to copy it in the appropriate place:

sudo cp bin/sftpplus-mft.plist /Library/LaunchDaemons/sftpplus-mft.plist

After the file is copied, you need to instruct launchd to load/read the new job definition file using the command:

sudo launchctl load /Library/LaunchDaemons/sftpplus-mft.plist

To stop SFTPPlus, use the following command:

sudo launchctl unload /Library/LaunchDaemons/sftpplus-mft.plist

In the case that there are problems starting the server, you can check the log files at /SFTPPLUS-INSTALL-DIR/log/launchd-stdout.log and /SFTPPLUS-INSTALL-DIR/log/launchd-stderr.log.

You can read more about launchd on the official documentation page

2.5.7. Listening on privileged ports¶

When running SFTPPlus as a regular user, it's not possible to bind privileged ports in the range 0-1024.

One generic method which works on any Unix-like system is to set up SFTPPlus to listen on a port above 1024, then set up port-forwarding in your firewall configuration.

For example, to set up port-forwarding using pf, we can use the loopback interface to keep things simple. However, you should adapt and extend the exemplified firewall rules to account for your own local configuration: different network interfaces, IPs, and other network traffic rules.

Step-by-step instructions on how to forward port 122 to 10022:

Create a pf anchor file for sftpplus in /etc/pf.anchors/sftpplus
with the following contents:
    rdr pass on lo0 inet proto tcp from any to 127.0.0.1
    port = 122 -> 127.0.0.1 port 10022
    (note the above 2 lines go into only one line, it has been
    split here for better readability)

Reference anchor in /etc/pf.conf, add:
    rdr-anchor "sftpplus"
    load anchor "sftpplus" from "/etc/pf.anchors/sftpplus"

Enable and reload pf manually:
    $ sudo pfctl -ef /etc/pf.conf

Note: Updates to the OS may override the pf.conf file, make sure to
make a backup of it.

2.5.8. First Steps¶

After starting SFTPPlus, the Web Manager is a good way to visualize the current configuration that is available, and is even configurable itself.

We highly recommend going through the Getting Started on Windows guide or Getting Started on Linux guide first as it contains additional tips for new SFTPPlus installations.

There is also an FAQ section if you have an idea, but are in search of answers.

If you want to skip ahead, the Configuration Instructions or the Usage Instructions will contain detailed information to configure and operate SFTPPlus.