TFTP error cannot download Boot.ovl

Article:TECH108274  |  Created: 2002-01-11  |  Updated: 2007-01-12  |  Article URL
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Technical Solution


The Trivial File Transfer Protocol (TFTP) download of the Boot.ovl file fails or times out.

TFTP errors occur such as "access violation" or "file not found".


Configuring and troubleshooting TFTP servers

TFTP servers should run in secure mode which means that tftp access is restricted on a set of directories and their subdirectories. The directories valid for TFTP access usually are given on the TFTP server's command line.

Example 1: Registry entry to start the CCM TFTP service for Windows NT and Windows 2000:

"ImagePath"=hex(2):"e:\ccm\config\dbin\tftpd.exe -s run -d 0 c:\etc\integra\tftp"

Where the start options are:
-d0 debug mode (log level) 0
and the service is configured to deliver files from only the c:\etc\integra\tftp directory.

Example 2: Solaris TFTP daemon

In /etc/inetd.conf the following line provides access to the /tftpdir directory:
tftp dgram udp wait root /usr/sbin/in.tftpd in.tftpd -s /tftpboot

File access
TFTP services allow read access on files only if the files file system permission includes "world readable."
Write access is only possible in the following situations:
  • The file already exists.
  • This prevents disk abuse.
  • The file system permissions allow write access for everybody.
    This prevents overwriting a bootfile with a virus, for example.
DHCP/Bootp server configuration

Bootfile option
Which bootfile path needs to be entered in the DHCP or Bootdp configuration depends on the tftp server implementation. Some TFTP servers, such as the CCM TFTP service for Windows NT, need the absolute path. If the Boot.ovl file resides in C:\Etc\Integra\Tftp, then the bootfile option value must be /etc/integra/tftp/boot.ovl.

Other TFTP servers, like the Solaris server, interpret the bootfile path relative to the directory that has been defined in the secure mode configuration. A secure mode directory /tftpdir and a bootfile option value /ccmboot/boot.ovl match the file /tftpdir/ccmboot/boot.ovl in the UNIX file system.

Both on UNIX and Windows NT systems a command-line TFTP client program exists. This program can but doesn't need to be called on the cmputer on which the TFTP server is running.
  • Unix:
    tftp get /tftpboot/ccmboot/boot.ovl
  • Windows NT
    tftp.exe -i get /etc/integra/tftp/boot.ovl
If on your CCM client computer you get a file access error or file not found message, then proceed according to the following checklist:
  1. Check which DHCP or Bootp server answered you client computers request.
    Usually this servers IP address is displayed on the clients screen. If you can't find this information on the screen you may need to use a network sniffer.
  2. Check the bootfile option set on this DHCP/Bootp server and find out whether the boot.ovl file exists at this place and whether it is world readable.
  3. Check whether the bootfile option was sent to your CCM client computer.
    Some Bootproms write the file name on the screen. If you can't find this information on the screen you may need to use a network sniffer.
  4. Try to download boot.ovl using the command-line TFTP programm on the host where your tftp server is running.
    1. Double check the bootfile name. It must be an absolute path where the drive letter is omitted.
    2. Is the TFTP server running?
    3. Look for errors in the log files of your TFTP server
    4. Is the UDP port 69 listed in the services file?
    5. If the boot.ovl file can be downloaded with the command-line tool, run the command-line tool from the same network segment where your CCM client computer resides.
      • If the download works, then your CCM client computer is requesting the wrong file.
      • If the download fails then UDP port 69 may be blocked by your router.

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