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TFTP Setup for Diskless Boot

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Enable TFTP Services on server.

Create new tftp directory in /opt/services tree

mkdir -p /opt/services/tftpboot

edit /etc/xinetd.d/tftp

• Change the line disable=yes to disable=no
• Change the TFTP data directory in the server_args line.

  # 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 /var/lib/tftpboot
          server_args             = -s /opt/services/tftpboot
  #        disable                 = yes
          disable                 = no
          per_source              = 11
          cps                     = 100 2
          flags                   = IPv4
  }
  

Restart the xinetd service

service xinetd restart

Populate the TFTP area

Minimally, /opt/services/tftpboot should look like

 
[root@usno-serv-1 tftpboot]# tree
.
|-- linux
|   |-- sysimage.cpio.gz
|   `-- vmlinuz-2.6.32-220.el6.x86_64
|-- pxelinux.0
|-- pxelinux.cfg
    `-- default

2 directories, 5 files
[root@usno-serv-1 tftpboot]#

Perform the following to set up the basic structure and partially populate:

cd /opt/services/tftpboot
mkdir linux
mkdir pxelinux.cfg
cp /usr/share/syslinux/pxelinux.0 .

Other kernels and boot images can be added later and nodes configured to use them using config files in the pxelinux.cfg directory. A node can use a different configuration file based on it's IP address as given by DHCP. Name the file after the IP address converted to hex. The utility /usr/bin/gethostip can makes this easy. e.g. for node-3;

[root@usno-serv-1 build]# gethostip node-3
node-3.usno.aoc.nrao.edu 10.1.34.103 0A012267
[root@usno-serv-1 build]#

So use pxelinux.cfg/0A012267 as the config file and node-3 will use it instead of pxelinux.cfg/default.

The kernel in this example, vmlinuz-2.6.32-220.el6.x86_64, should be the current kernel copied from the image build area, /opt/services/boot/build/0_OSimage/boot. See UsnoDifxDisklessBoot. e.g.:

cd /opt/services/tftpboot
cp /opt/services/boot/build/0_OSimage/boot/vmlinuz-2.6.32-279.el6.x86_64 linux/

The file pxelinux.cfg/default should look like,

default linux

label linux
  kernel linux/vmlinuz-2.6.32-220.el6.x86_64
    append initrd=linux/sysimage.cpio.gz root=/dev/ram rw ip=dhcp

With proper values to match the kernel and the ramdisk image (initrd=).

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Allow TFTP

USNO security requires TCP wrappers

echo "in.tftpd:10.1.34.*      #for booting diskless nodes" >> /etc/hosts.allow
echo "rpcbind:10.1.34.*, 127.0.0.1             #for NFS to diskless nodes" >> /etc/hosts.allow
echo "mountd:10.1.34.*, 127.0.0.1              #for NFS to diskless nodes" >> /etc/hosts.allow

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