Thursday, January 3, 2008

Bypassing Boot Server Installation When Jumpstarting Across Subnets


Today I thought we'd go with a little "trickery," although this isn't really a trick; it's just not the way you're supposed to use Solaris' Jumpstart when Jumpstarting across subnets. It has it's benefits, though, aside from the obvious (I'll get to that at the end :) Note that some of this process varies in Solaris 10 (insofar as the starting up of services goes, but we'll hit that in a later post, since they've completely changed the procedure). This will work, almost word for word in Solaris versions up to and including 9.

Now, to get started:

In order to install and configure a system across subnets, it is recommended by Sun that the Jumpstart client be configured to run through a Boot Server on that client's subnet (and on a separate server for every subnet that you need to hop through). This involves executing the add_install_client command on the Boot Server on the same subnet as the client, and installing all the software required to run a Boot Server.

It is possible, however, to use any server on the client's subnet as a conduit through which to pass the boot, installation and configuration information between the client and server without expending the time, or wasting the resources, that installing a Boot Server on the intermediate client requires.

In order to make this seamless connection between subnets possible, and allow your Jumpstart client to install and configure itself through the server, you will need to modify certain files and ensure that several daemon processes are active on the gateway computer.

1. First, be sure to update the gateway computer's /etc/hosts and /etc/ethers files to include entries for the install client. The gateway computer is were we'd normally have to consume the disk space to actually set up a legitimate Boot Server.

2. Ensure that the proper daemons are active on the gateway computer. You may need to start up rarpd, bootparamd and tftpd (which is, by default, commented out of the /etc/inetd.conf file, so you'll need to "kill -1" or "kill -HUP" the inetd process after uncommenting that entry).

3. Create an entry for the install client in the /etc/bootparams file. You can generally copy the entry that exists in your Jumpstart server's /etc/bootparams file, but you will need to make a few changes:

a. Translate the hostname of the server (if entered in this fashion) to it's I.P. Address.

b. Adding an ns entry won't hurt. Assuming a Jumpstart server with I.P. Address, no supported nameservice active and a netmask of, you can add this to the end of the /etc/bootparams entry for your client (on the gateway computer, of course):


ns= <-- Add a colon to the beginning of this addition if the /etc/bootparams entry doesn't end with one!

4. Create a directory off of the root partition named tftpboot.


mkdir /tftpboot

5. Populate your /tftpboot directory with the contents of the /tftpboot directory on your Jumpstart server host and ensure all file and directory ownership and permissions are the same. If you know exactly what to look for, you really only need to copy the files that are relevant to the server you're trying to Jumpstart, but you can't go wrong by copying them all.

Now, the intermediate host/server should be prepared to accept your Jumpstart client's rarp requests and transparently forward them to your Jumpstart server on the alternate subnet!

Note that you can do this on as many servers as you like (if, for instance, you have to take multiple hops across subnets to get to your Jumpstart server). Just duplicate on each intermediate host. The only thing you'll have to change (and sometimes you won't even have to do this) is the Jumpstart host listed in /etc/bootparams on the servers that come before you hit the server that can get to the Jumpstart server. You can create a simple daisy chain by replacing the Jumpstart server name with the IP of the next host along the way in the /etc/bootparams file. Hopefully, you won't ever have to hop more than once to get to an internal network that has a Jumpstart server on it.

And finally, as promised, the extra benefit: If you ever get stuck at home and have to boot a Solaris box that won't come up, the box is on a subnet without a Jumpstart (or Boot) server and there's no one at the office to put in a CD for you to boot off of, you can use this exact same procedure to hop subnets and get to single user mode with:

boot net -s


, Mike