TFTP (trivial file transfer protocol) provides a convenient means of quickly transferring a Cisco IOS image to a firewall over an ethernet interface. This procedure is substantially faster than transferring over a serial port.
Step 1: Copy the IOS binary file to the TFTP directory.
By default on most UNIX systems, the default data directory for the TFTP server is /tftpboot. Copy the IOS image file to this directory and make sure it is world readable (i.e., chmod 544 /tftpboot/filename.bin). The first time you try this procedure, or anytime you experience troubles, test the TFTP server configuration with the tftp client:
You can change directory to /tmp or any other directory that does not contain the image file. You must use the exact name of your binary file.
If there are no error messages, proceed; otherwise troubleshoot based on the error message.
Step 2: Configure an ethernet interface on the firewall if not already configured.
Test the configuration by pinging the ip address of the TFTP server from the firewall.
Step 3: Load the IOS image
From enable mode on the firewall, the following command will load the IOS image in filename.bin from the TFTP server at IP address 192.168.200.15:
copy tftp://192.168.200.15/filename.bin flash
You will be asked to confirm this procedure. Press ENTER to confirm.
Step 4: Restart the firewall
From enable mode, use the ‘reload’ command to restart the firewall.