[syslinux] Cannot chain to another PXE server on the same subnet

Gene Cumm gene.cumm at gmail.com
Fri Mar 7 02:49:04 PST 2014

On Fri, Mar 7, 2014 at 2:33 AM, Vieri <rentorbuy at yahoo.com> wrote:

> So I take it it's more of a DHCP hack in which:
> 1- client boots and gets DHCP response from with PXE syslinux info
> 2- client loads pxelinux.0 menu and selects menu that chains to Altiris PXE menu except, instead of calling pxechain.com or pxechn.c32 with the Altiris server's IP address, the client should "re-netboot" but this time, the DHCP server at should not include any PXE information at all for this particular client/MAC, so Altiris can kick in.
> I don't know how to do this but is this basically what you're suggesting?

1) Thinking about the responses again, I'm absolutely surprised that
you can even boot PXELINUX.  I would have expected the response from
the Altiris server to override your attempts to block it.

2) There's at least one more thing we can try, a very long option 43.
Either use the text-decimal tcpdump or a tool that can read the pcap
(like Wireshark) and create a single large colon-separated string
representation of the 3 option 43 values (should be over 1200
characters long, 3 times total length minus 1).

Using wireshark and right-clicking on each option 43 instance, copy,
bytes, as hexstream, and leaving the option 255s in I get:


So try "-o 43.x=<above-string>" on the append line.  If that doesn't
work, strip the two "ff"s in the middle.  Otherwise, this is going to
need rework for the pack/unpack and pxechn.c32


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