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4. Configuring BOOTP/DHCP and NFS

If you're wondering what on earth this BOOTP and DHCP stuff is, more information is available at the DHCP WWW site. NFS is documented separately in detail in the NFS HOWTO.

In the BOOTP/DHCP + NFS configuration we're discussing, the KickStart config file should be NFS mountable by the machine being installed from /kickstart/IPADDR-kickstart on the BOOTP/DHCP server, where IPADDR is the IP address of the new machine, e.g. /kickstart/198.168.254.254-kickstart for the machine 198.168.254.254.

In theory you should be able to override this location by returning the bf parameter (boot file) in your BOOTP/DHCP response. It may even be possible to have this NFS mounted off another machine entirely.

To NFS export some directories from an existing Linux box, create the file /etc/exports with contents something like:

/kickstart *.swedish-chef.org(ro,no_root_squash)
/mnt/cdrom *.swedish-chef.org(ro,no_root_squash)

Note that if you didn't register the IP addresses you're going to be using in the DNS, you may be told to get lost by the NFS server and/or the RPC portmapper. In this you can probably get away with putting IP address/netmask pairs in the config files, e.g.

/kickstart 198.168.254.0/255.255.255.0(ro,no_root_squash)

and in /etc/hosts.allow:

ALL: 194.82.103.0/255.255.255.0: ALLOW

Be aware that if you include a root password in your KickStart config file, or NFS export directories containing sensitive information, you should take care to expose this information to as few people as possible. This can be done by making the NFS export permissions as fine grained as possible, e.g. by specifying a particular host or subnet to export to rather than a whole domain.

Most NFS servers require you to tell mountd and nfsd (on some versions of Unix they're prefixed with a rpc.) that the /etc/exports file has changed - usually by sending a SIGHUP. There's often a program or script called exportfs, which will do this for you, e.g.

# exportfs -a

If you didn't have NFS up and running when this machine was booted, the directories may not be exported automatically. Try rebooting, or running the following programs as root:

# portmap
# rpc.nfsd
# rpc.mountd

As noted, on some systems the rpc. prefix isn't used. In most modern Unix distributions, these programs can be found in the /usr/sbin directory. This might not be in your path already. The portmap program is also sometimes called rpcbind, e.g. on Solaris.

If you're using the CMU BOOTP server with DHCP and dynamic addressing extensions referred to earlier, a sample /etc/bootptab entry (/etc/bootptab is the normal location of the BOOTP/DHCP configuration file) would look something like this:

  .dynamic-1:ip=198.168.254.128:T254=0x30:T250="ds=198.168.254.2:
  dn=swedish-chef.org:sm=255.255.255.0:gw=198.168.254.1:
  dl=0xFFFFFFFF":

(wrapped for clarity)

This says to allocate IP addresses dynamically on encountering new machines, starting at 198.168.254.128 and continuing for the next 48 (the hexadecimal value 30) addresses. Each client will be passed back the value of T250. In this case that sets:

There seem to be a number of other versions of this server kicking around which do not support dynamic addressing. For these, you would have to list the hardware (typically Ethernet MAC) address of each to-be-installed machine in /etc/bootptab, and the entries would look something like this:

bork.swedish-chef.org:\
  ip=198.168.254.128:\
  ha=0000E8188E56:\
  ds=198.168.254.2:\
  dn=swedish-chef.org:\
  sm=255.255.255.0:\
  gw=198.168.254.1:\
  dl=0xFFFFFFFF":

Note that the parameter ha corresponds to the hardware address of the machine being installed.


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