9.3. Deploying a Tang server with SELinux in enforcing mode

Procedure

1. To install the tang package and its dependencies, enter the following command as root:

   # dnf install tang

2. Pick an unoccupied port, for example, 7500/tcp, and allow the tangd service to bind to that port:

   # semanage port -a -t tangd_port_t -p tcp 7500

   Note that a port can be used only by one service at a time.

3. Open the port in the firewall:

   # firewall-cmd --add-port=7500/tcp
   # firewall-cmd --runtime-to-permanent

4. Enable the tangd service:

   # systemctl enable tangd.socket

5. Create an override file:

   # systemctl edit tangd.socket

6. In the following editor screen, which opens an empty override.conf file located in the /etc/systemd/system/tangd.socket.d/ directory, change the default port for the Tang server from 80 to the previously picked number. Insert the following code snippet between the lines starting with # Anything between here and # Lines below this, otherwise the system discards your changes:

   [Socket]
   ListenStream=
   ListenStream=7500

7. Save the changes and exit the editor. In the default vi editor, you can do that by pressing Esc to switch into command mode, entering :wq, and pressing Enter.

8. Reload the changed configuration:

   # systemctl daemon-reload

9. Check that your configuration is working:

   # systemctl show tangd.socket -p Listen
   Listen=[::]:7500 (Stream)

10. Start the tangd service:

    # systemctl restart tangd.socket

    Because tangd uses the systemd socket activation mechanism, the server starts as soon as the first connection comes in. A new set of cryptographic keys is automatically generated at the first start. To perform cryptographic operations such as manual key generation, use the jose utility as described in the jose(1) man page on your system.