So I was wondering about rolling out distros to lots of PC's via netboot.
The a colleague dropped an aging laptop minus a CD drive on my desk and asked me to upgrade it for him. The first N attempts failed... but since I have the thing on a minihub and I have wireshark.... here is an interesting (to me at least) trace of how DHCP and Netboot works in the wild... Ok, the full sequence is this... The laptop broadcasts DHCP DISCOVER with parameters that ask for, amongst other id, subnet router and bootfile. Three IP addresses (on our LAN) wake up and broadcast 196.168.50.1, 196.168.50.2, 196.168.50.30 with a DHCP Offer. The first two offer ip address/ subnet / router info. eg. The 196.168.50.1 responds with offer of ip address. eg. Your (client) IP address: 196.168.113.203 plus information on the lease time. The third server 196.168.50.30 _doesn't_ offer an ipadress but gives Option: (t=60,l=9) Vendor class identifier = "PXEClient" The laptop then broadcasts a DHCP Request for 196.168.113.203 The first DHCP server 196.168.50.1 replies with a DHCP ACK. The laptop then, curiously enough, since the mac was in the offer, sends an ARP for 196.168.50.30, and gets a reply. (Curiously enough the replying machine type claims to be vmware) The laptop then adopts, the ip address 196.168.113.203 granted by the first server, and sends direct a DHCP Request to 196.168.50.30 for amongst other things, the bootfile name. The server 196.168.50.30 responds, with amongst other things, it's hostname... Server host name: SOMEHOSTNAME.SOMEDOMAIN.CO.NZ and bootfile name... Boot file name: OSChooser\i386\startrom.com There after it tftp's that down... Curiously that hostname doesn't seem to be known to the DNS. ie. There probably is a magic way of configuring my DHCP server not to respond with IP addresses, but merely an offer of a bootfile, that the operator at the laptop end can choose from. Sigh! Now if I can only work out what that is... I love having wireshark (on a minihub) :-)) John Carter Phone : (64)(3) 358 6639 Tait Electronics Fax : (64)(3) 359 4632 PO Box 1645 Christchurch Email : [EMAIL PROTECTED] New Zealand
