unique root path for each IP?

[jrgruher]

Hi folks. This is actually a ISC DHCP server question but I wonder if someone here may have dealt with the same issue and know the solution.

I have a bed of diskless clients which boot over iSCSI using iPXE. Each client receives an IP and root path from the DHCP server, the root path points to a unique iSCSI target. The way this is implemented in the DHCP server today is to statically pair the IP and root path with each client’s MAC address, for example:

host initiator1 {
hardware ethernet 00:0C:29:A8:93F;
fixed-address 10.0.0.1;
filename "";
option root-path "iscsi:initiator1.example.com::::target00";
}

The downside of this is that I have to know the MAC of every client. I don’t actually care which client gets which IP or which target, all clients are identical, so as long as they all get a unique IP and target not given to any other client at the same time I’m good. Ideally I would just like to pair the IPs and targets, since the DHCP server already handles keeping IPs unique a 1:1 pairing with targets will also ensure targets are unique. Is it possible to set up dhcpd.conf to do something like this:

When issuing 10.0.0.10 issue root path "iscsi:initiator1.example.com::::target10"
When issuing 10.0.0.11 issue root path "iscsi:initiator1.example.com::::target11"
…
When issuing 10.0.0.95 issue root path "iscsi:initiator1.example.com::::target95"


Or even more compact, can we do something like this:

When issuing 10.0.0.X issue root path "iscsi:initiator1.example.com::::targetX"

Thanks,
Joe

[mcb30]

(2014-07-18 17:32)jrgruher Wrote:  Or even more compact, can we do something like this:

When issuing 10.0.0.X issue root path "iscsi:initiator1.example.com::::targetX"

Yes, ISC dhcpd can do this. You want something like:

Code:

option root-path =
        concat ( "iscsi:initiator1.example.com::::target",
                 binary-to-ascii ( 10, 8, "", suffix ( leased-address, 1 ) ) );

Michael

[jrgruher]

Very cool, thanks for the pointer! I'll investigate along these lines.