Configuring TFTP to Communicate on a Non-Default Port

The Trivial File Transfer Protocol (TFTP) is a simple client-server protocol used for transferring files over a network. By default, TFTP communicates over port 69, but in some scenarios, it might be necessary to use a different port. This guide will walk you through the steps to configure both the TFTP client and server to use a non-default port, including necessary settings and configurations.

TFTP Client Configuration

To make a TFTP client communicate with a port number other than 69, you need to specify the port in the client's command-line options or configuration files. The exact syntax for specifying the port number may vary depending on the client software you are using.

Specify the Port

Most TFTP clients allow you to specify a different port number in their command-line options or configuration files. Here's an example using the tftp command-line utility:

bash tftp -p port_number server_ip or tftp server_ip -p port_number

Note that not all TFTP clients support specifying a port directly in the command line. In such cases, you may need to edit the client's configuration file or consult the specific client's documentation for the correct command-line options.

TFTP Server Configuration

On the TFTP server side, you need to ensure that it is listening on the specified port. This might involve modifying the server's configuration file or command-line options when starting the server.

Configure the TFTP Server

If you are using tftpd-hpa, for example, you might edit the configuration file often located at /etc/default/tftpd-hpa to include the desired port:

bash TFTP_PORTport_number

For other TFTP servers, refer to their respective documentation for the correct way to set the listening port.

Firewall and Network Configuration

To ensure that the TFTP client and server can communicate on the non-default port, you need to configure the firewall settings.

Check Firewall Settings

Ensure that any firewalls, both on the server and any intermediate network devices, allow traffic on the new port. You may need to create a rule to permit incoming connections on that port.

Restart the Server

After making changes to the configuration, restart the TFTP server to apply the new settings.

Example

If you want your TFTP server to listen on port 12345 instead of the default port 69, follow these steps:

Set the TFTP server configuration to listen on port 12345. Specify the port in your TFTP client command, for example: Ensure firewall rules allow traffic on port 12345. Restart the TFTP server to apply the new settings.

Here's an example of modifying the /etc/default/tftpd-hpa file to listen on port 12345:

bash TFTP_PORT12345

After making these changes, restart the TFTP server and ensure that your firewall is configured to allow traffic on port 12345.

Conclusion

By ensuring both the client and server are configured to use the same port and verifying network settings, you should be able to successfully communicate using a non-default port for TFTP. Always refer to the specific documentation for your TFTP client and server for precise configuration options.