Troubleshoot TFTP

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Revision as of 22:44, 13 June 2015 by Tom-elliott.7271 (talk | contribs) (Common problems and fixes)
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TFTP's roles in FOG

TFTP is used to download the boot-file specified by either DHCP or ProxyDHCP. TFTP is very simple and has very little protections in place; Generally read-only is preferred for files offered by TFTP, however full permissions will work too. Normally, the boot-files for FOG are located in /tftpboot Generally, TFTP offers these boot files.

Testing TFTP

Try to get a file with Linux:

This is ran from a separate Linux machine, NOT your FOG server.

Normally, you can use your Linux installation medium to live boot on another computer.

tftp -v x.x.x.x -c get undionly.kpxe
Connected to x.x.x.x (x.x.x.x), port 69
getting from x.x.x.x:undionly.kpxe to undionly.kpxe [netascii]
Received 89509 bytes in 0.0 seconds [84047115 bit/s]

Try to get a file with Windows:

Using Windows 7:

tftp x.x.x.x get undionly.kpxe

Using Windows XP:

tftp –i x.x.x.x get undionly.kpxe

Testing using Windows

Template:Windows TFTP

TFTP Service

Fedora 20/21


systemctl status xinetd.service
systemctl enable xinetd.service
systemctl restart xinetd.service


newer systems:


service tftpd-hpa status
service tftpd-hpa restart
service tftpd-hpa enable

older systems:


sudo /etc/init.d/xinetd status
sudo /etc/init.d/xinetd restart
sudo /etc/init.d/xinetd enable

TFTP Settings file




To display /etc/xinetd.d/tftp:

cat /etc/xinetd.d/tftp

It should look a whole lot like this:

# default: off
# description: The tftp server serves files using the trivial file transfer #   protocol.  
#The tftp protocol is often used to boot diskless workstations, download configuration files to network-aware printers, 
# and to start the installation process for some operating systems.
service tftp
        socket_type             = dgram
        protocol                = udp
        wait                    = yes
        user                    = root
        server                  = /usr/sbin/in.tftpd
        server_args             = -s /tftpboot
        disable                 = no
        per_source              = 11
        cps                     = 100 2
        flags                   = IPv4

To edit /etc/xinetd.d/tftp:

sudo vi /etc/xinetd.d/tftp

Explanation of settings for /etc/xinetd.d/tftp:

man xinetd.conf




To display /etc/default/tftpd-hpa:

cat /etc/default/tftpd-hpa

It should look a whole lot like this:

# /etc/default/tftpd-hpa
# FOG Modified version

To edit /etc/default/tftpd-hpa:

sudo vi /etc/default/tftpd-hpa

Explanation of settings for /etc/default/tftpd-hpa:

man tftpd-hpa

Instructions on using Vi:


FOG Configuration (web interface)

x.x.x.x/fog/management -> FOG Configuration -> FOG Settings -> TFTP Server ->

Ensure that the below settings are set to a local FOG linux user that actually exists. Ensure correct password is provided. Ensure that the supplied user has permission to the /tftpboot directory (see permissions).



Disable & Verify Firewall

Template:Disable & Verify Firewall

It's necessary to disable the Windows firewall when using windows for testing. The below image demonstrates disabling the firewall which allows TFTP traffic to pass.

TFTP Windows Firewall.png


Check permissions on /tftpboot directory by using:

ls -laR /tftpboot

Set permissions to allow everyone full access to /tftpboot and all contents:

chmod -R 777 /tftpboot

See example permissions below:

total 3960
drwxr-xr-x   4 fog  root   4096 Apr 29 18:37 .
dr-xr-xr-x. 23 root root   4096 Apr 29 18:37 ..
-rw-r--r--   1 fog  root    840 Apr 29 18:37 boot.txt
-rw-r--r--   1 root root    397 Apr 29 18:37 default.ipxe
drwxr-xr-x   2 fog  root   4096 Apr 29 18:37 i386-efi
-rw-r--r--   1 fog  root 171232 Apr 29 18:37 intel.efi
-rw-r--r--   1 fog  root  89120 Apr 29 18:37 intel.kkpxe
-rw-r--r--   1 fog  root  89168 Apr 29 18:37 intel.kpxe
-rw-r--r--   1 fog  root  89153 Apr 29 18:37 intel.pxe
-rw-r--r--   1 fog  root 890208 Apr 29 18:37 ipxe.efi
-rw-r--r--   1 fog  root 329014 Apr 29 18:37 ipxe.kkpxe
-rw-r--r--   1 fog  root 329062 Apr 29 18:37 ipxe.kpxe
-rw-r--r--   1 fog  root 328438 Apr 29 18:37 ipxe.krn
-rw-r--r--   1 fog  root 329115 Apr 29 18:37 ipxe.pxe
-rw-r--r--   1 fog  root 123448 Apr 29 18:37 ldlinux.c32
-rw-r--r--   1 fog  root  26140 Apr 29 18:37 memdisk
-rw-r--r--   1 fog  root  29208 Apr 29 18:37 menu.c32
-rw-r--r--   1 fog  root  43210 Apr 29 18:37 pxelinux.0
-rw-r--r--   1 fog  root  43210 Apr 29 18:37 pxelinux.0.old
drwxr-xr-x   2 fog  root   4096 Apr 29 18:37 pxelinux.cfg
-rw-r--r--   1 fog  root 170912 Apr 29 18:37 realtek.efi
-rw-r--r--   1 fog  root  90028 Apr 29 18:37 realtek.kkpxe
-rw-r--r--   1 fog  root  90076 Apr 29 18:37 realtek.kpxe
-rw-r--r--   1 fog  root  90105 Apr 29 18:37 realtek.pxe
-rw-r--r--   1 fog  root 170112 Apr 29 18:37 snp.efi
-rw-r--r--   1 fog  root 170272 Apr 29 18:37 snponly.efi
-rw-r--r--   1 fog  root  88763 Apr 29 18:37 undionly.kkpxe
-rw-r--r--   1 fog  root  88811 Apr 29 18:37 undionly.kpxe
-rw-r--r--   1 fog  root  88856 Apr 29 18:37 undionly.pxe
-rw-r--r--   1 fog  root  29728 Apr 29 18:37 vesamenu.c32

total 1348
drwxr-xr-x 2 fog root   4096 Apr 29 18:37 .
drwxr-xr-x 4 fog root   4096 Apr 29 18:37 ..
-rw-r--r-- 1 fog root 137280 Apr 29 18:37 intel.efi
-rw-r--r-- 1 fog root 812864 Apr 29 18:37 ipxe.efi
-rw-r--r-- 1 fog root 137664 Apr 29 18:37 realtek.efi
-rw-r--r-- 1 fog root 137088 Apr 29 18:37 snp.efi
-rw-r--r-- 1 fog root 137216 Apr 29 18:37 snponly.efi

total 12
drwxr-xr-x 2 fog root 4096 Apr 29 18:37 .
drwxr-xr-x 4 fog root 4096 Apr 29 18:37 ..
-rw-r--r-- 1 fog root  160 Apr 29 18:37 default

Check Network Switch settings

See IPXE for network switch settings concerning STP/portfast/etc.

Template:DHCP Settings


Using DHCP or ProxyDHCP, you can capture the packets sent to and from a particular host using TCPDump.


Using the above method and filter, this is what a BROKEN Option 067 (or ProxyDHCP) conversation looks like:

Broken dnsmasq.png

In this case, DHCP (or dnsmasq) boot file name is not configured correctly, the boot file does not exist, or TFTP is not configured properly.

Common problems and fixes

My problem isn't in the WiKi!

My problem isn't in the WiKi!

Failed to load libcom32.c32 / Failed to load COM32 file vesamenu.c32


You see a rolling error that says:

Failed to load libcom32.c32
Failed to load COM32 file vesamenu.c32

And the host won't boot to the network.


This error has been seen in FOG Trunk (r3500s), and could possibly occur in 1.2.0 also.

This is caused by DHCP option 067 being set to pxelinux.0

Some people have large DHCP scopes set. Sometimes a higher-up global scope/setting can override local scope settings for a particular site.

Whatever the case, DHCP is indeed handing out pxelinux.0 and that's generally not advised.

For ProxyDHCP users (dnsmasq), you should look to see what boot file is being handed out.

For those that have inherited / upgraded a FOG server and are trying to use standard DHCP for 066 and 067, it's possible that ProxyDHCP might be running on your FOG server, and it's possible that ProxyDHCP is re-setting 067 on your network hosts to an incorrect value of pxelinux.0 which would cause this error.

You should use either undionly.kpxe or undionly.kkpxe for BIOS booting for option 067, or use any of the .efi files inside of /tftpboot for UEFI booting.

Please see this article for more details about the various boot files available in fog: Filename Information

Unable to connect to tftp server

For Versions Before 0.24

This seems to be caused by a password issue,

1. From the fog management interface, go to users.
2. Reset the fog user password.
3. Click the "I" icon - "Other Information"
4. Click "Fog Settings" in the menu on the left
5. Replace the FOG_TFTP_FTP_PASSWORD and the FOG_NFS_FTP_PASSWORD fields under FOG settings with 
   your Linux fog user password. (Seems like FOG_NFS_FTP_PASSWORD is gone for ver .24).

For Versions .24-.32

  • Reset the local password for user fog with: [sudo] passwd fog
  • In management front end, go to Storage Management -> All Storage Nodes
  • Click on DefaultMember
  • Change the Management Password to match the password you just changed.
  • Then go to Other Information and change FOG_TFTP_FTP_PASSWORD also.

  • Go to your fog web location, on Red Hat and CentOS is in:

Then open the file:


and check the values of: TFTP_FTP_PASSWORD and STORAGE_FTP_PASSWORD

These MUST match the password you set above, if not write them properly in here

Finally reload of the service

/etc/init.d/vsftpd reload

Verify Server Settings

If you have modified your server setup since first install, then the new changes must be updated and verified in the Fog Settings menu. It might not be enough to just re-run the installer. For instance, a new IP lease will cause the server to show the Unable to connect to tftp server error message.

  • Go to the "I" icon, which is the About menu in 0.29
  • Select Fog Settings and navigate down to TFTP Settings and verify that all options are correct for your setup.

Ensure nothing else on the network is conflicting with the DHCP server

I had this error the past two days and tried all of the standard suggestions. Finally Wireshark came to the rescue. I discovered a second, feral DHCP server on the network that wasn't issuing IP addresses but must have been running interference somehow. When I disconnected it from the network, PXE boot worked as expected.