If you open a command prompt window and issue the command netstat -anp udp and pipe the output into the find, you should also see the system is listening on all network interfaces, i.e., 0.0.0.0, on UDP port 69.

C:\Users\Public\Downloads>netstat -anp udp | find "0.0.0.0:69"
  UDP    0.0.0.0:69             *:*

C:\Users\Public\Downloads>

The installation program also installs a TFTP service, which is set to run automatically when Windows boots; you can see information on the service if you open Services and scroll through the list of services on the system — you can open a Services window by typing services.msc at a command prompt window and hitting Enter.

[ More Info ]

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The Trivial File Transport Protocol (TFTP) proivides a mechanism to read files from or write files to a remote server. It is similar to the File Transfer Protocol (FTP), but doesn't have all of the features of FTP, such as an authentication mechanism.

The instructions below were written for the CentOS distribution of Linux, but TFTP server software is available for Linux, Unix, Windows and other operating systems. For Linux systems that use the Red Hat Package Manager (RPM) package management system, you can determine if the tftp-server package is installed with the command rpm -qi tftp-server.

# rpm -qi tftp-server
package tftp-server is not installed

The tftp-server package depends on the xinetd package; you can check if that package is installed with rpm -qi xinetd. If it isn't installed and you use the Yellow dog Updater, Modified (YUM) package management utility, you can install both packages with yum install tftp-server xinetd. To install just the tftp-server package, use yum install tftp-server. The installation of the tftp-server package will create the directory /tftpboot on the system. The directory should be set to 755 for tftp clients to be able to read from or write to files in the directory.

# ls -ld /tftpboot
drwxr-xr-x 2 root root 4096 Dec 24 14:15 /tftpboot

You next need to turn on the tftp service with the chkconfig command.

# chkconfig tftp on

You can verify that the service is available with chkconfig --list tftp.

# chkconfig --list tftp
tftp            on

TFTP uses the User Datagram Protocol and listens for data on port 69, so you can also use netstat -a | grep tftp to check on whether the system is listening for data on port 69. You should see something like the following if it is listening:

udp        0      0 *:tftp                      *:*

If you have firewall software running on the TFTP server, you will also need to allow connectivity to UDP port 69 through the firewall. You can do this on a CentOS system through the GUI by taking the following steps:

1. Click on System.
2. Click on Administration.
3. Select Security Level and Firewall
4. Under Firewall Options, select other ports.
5. Click on the Add button.
6. Put 69 in the port field and select udp for the protocol.
7. Click on OK.
8. Click on OK again.
9. When prompted to override any existing firewall configuration, click on Yes.

To be able to write to a file on the tftp server, e.g. a file named firewall-log.txt in the /tftpboot directory, you need to first create the file with the touch command and then set the permissions on the file so it is "world" writable.

# touch /tftpboot/firewall-log.txt
# chmod 666 /tftpboot/firewall-log.txt

Once you have the TFTP server configured, you can then transfer files from the tftp client to the server.

References:

1. TFTP Server
   Date: January 8, 2007
   CentOS
2. Configuring a TFTP Server
   Date: June 5, 2003
   ONLamp.com

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