Netboot Process


Hey folks.

Another query...

So the system I have taken over here has three Jamf NetSUS 4.1.0 servers set up purely to handle Netboot, configured for different VLANs on different sites. All has been working well, but last week one of them suddenly stopped functioning as normal. It's a bit odd, and I'm slightly puzzled:

  • I can SSH to the server without any problem and get to the web interface, and all the usual services seem to be started

  • Tailing the system log shows none of the usual dhcp traffic that happens on the other servers that currently still work fine

  • Asking the network guys to check, none of the IP Helpers have been changed on the Cisco kit, everything is as it was before

  • We have attempted assigning a test Mac an IP in the same subnet as the Netboot server (to try and rule out any IP Helper problems), but the Netboot option still doesn't show up when holding the option key

  • If I allow the test Mac to boot normally and log in to it with the same IP still configured, I can see the Netboot server listed in the startup disks in sys prefs, and restarting from that drive finally shows some traffic in the server logs (picks up the Mac IP and states that it's running via the "System Prefs Port") but then the Mac seems to do nothing for a bit and then boot back into the main HDD.

Am I right in thinking that the Startup Manager on the Mac should be trying to pick up an IP via DHCP, but if it fails, it won't show the Netboot option? That's the only thing I can think of here, but given DHCP works fine when the Mac is booted normally... I'm at a bit of a loss.

Any tips greatly received!



What model systems are you attempting to NetBoot and are you using any network adapters?

Have seen issues with certain network adapters that appears are not compatible to get a system online at the boot options screen to see my NetBoot servers.


A variety of different Macs, and all straight from the onboard socket, no network adapters present at all. I have now updated the NetSUS application to the latest version on this problematic server but I'm still seeing nothing in the logs.

Just to rule out the network and IP Helper side of things... am I right in thinking that as long as the Mac is in the exact same subnet as the NetBoot server and I boot the Mac to the startup manager via holding option, I should then be able to see the advertised .nbi file from that server? There's no local configuration on the Mac that needs to happen before that point?


...and it's fixed. Turned out the network team had switched on a DHCP snooping protocol that was blocking packets to the server. They added it to a trusted list and now all is ok. Whoops.