====== dnsmasq ======

[[https://thekelleys.org.uk/dnsmasq/doc.html|dnsmasq]] has gained popularity in recent years. It can easily be configured to support iPXE.

===== DHCP proxy =====

If you can't modify your existing dhcp then a proxy is the way to go.
It uses ''option 43'' to display a menu and ''UDP port 4011'' for the PXE configuration, while the IP and other information is given by your default DHCP server.


To use [[:howto:chainloading|PXE chainloading]], we will configure dnsmasq to give out [[https://boot.ipxe.org/undionly.kpxe|undionly.kpxe]] or [[https://boot.ipxe.org/snponly.efi|snponly.efi]] to legacy PXE clients, and then hand out the "real" boot configuration only to iPXE clients using ''tags''.  iPXE feature options will be used to verify that it has all features that we want, see [[:howto:dhcpd#ipxe-specific_options|dhcp page]] for all iPXE-specific options.

Things to modify:
  * ''10.1.1.0'' - your subnet
  * ''eth0'' - interface to listen on, or switch to bind-dynamic
  * ''10.1.1.2'' - your tftp server ip
  * ''http://boot.ipxe.org/demo/boot.php'' - script to run once inside iPXE

	# Known working dnsmasq version 2.85 config for iPXE proxydhcp usage
	# Debug logging
	log-debug
	
	# Disable DNS server
	port=0
	
	# send disable multicast and broadcast discovery, and to download the boot file immediately
	# DHCP_PXE_DISCOVERY_CONTROL, should be vendor option? Needs more understanding and source
	dhcp-option=vendor:PXEClient,6,2b
	
	# This range(s) is for the public interface, where dnsmasq functions
	# as a proxy DHCP server providing boot information but no IP leases.
	# Any ip in the subnet will do, so you may just put your server NIC ip here.
	dhcp-range=10.1.1.0,proxy
	
	interface=eth0
	# bind-dynamic - remove interface and use this instead to listen everywhere?
	# Disable re-use of the DHCP servername and filename fields as extra
	# option space. That's to avoid confusing some old or broken DHCP clients.
	dhcp-no-override
	
	#dhcp-match=set:<tag>,<option number>|option:<option name>|vi-encap:<enterprise>[,<value>]
	#dhcp-boot=[tag:<tag>,]<filename>,[<servername>[,<server address>|<tftp_servername>]]
	
	# Based on logic in https://gist.github.com/robinsmidsrod/4008017
	# iPXE sends a 175 option, checking suboptions
	dhcp-match=set:ipxe-http,175,19
	dhcp-match=set:ipxe-https,175,20
	dhcp-match=set:ipxe-menu,175,39
	# pcbios specific
	dhcp-match=set:ipxe-pxe,175,33
	dhcp-match=set:ipxe-bzimage,175,24
	dhcp-match=set:ipxe-iscsi,175,17
	# efi specific
	dhcp-match=set:ipxe-efi,175,36
	# combination
	# set ipxe-ok tag if we have correct combination
	# http && menu && iscsi ((pxe && bzimage) || efi)
	tag-if=set:ipxe-ok,tag:ipxe-http,tag:ipxe-menu,tag:ipxe-iscsi,tag:ipxe-pxe,tag:ipxe-bzimage
	tag-if=set:ipxe-ok,tag:ipxe-http,tag:ipxe-menu,tag:ipxe-iscsi,tag:ipxe-efi
	
	#pxe-service=[tag:<tag>,]<CSA>,<menu text>[,<basename>|<bootservicetype>][,<server address>|<server_name>]
	#pxe-prompt=[tag:<tag>,]<prompt>[,<timeout>]
	# these create option 43 cruft, which is required in proxy mode
	# TFTP IP is required on all dhcp-boot lines (unless dnsmasq itself acts as tftp server?)
	pxe-service=tag:!ipxe-ok,X86PC,PXE,undionly.kpxe,10.1.1.2
	pxe-service=tag:!ipxe-ok,IA32_EFI,PXE,snponlyx32.efi,10.1.1.2
	pxe-service=tag:!ipxe-ok,BC_EFI,PXE,snponly.efi,10.1.1.2
	pxe-service=tag:!ipxe-ok,X86-64_EFI,PXE,snponly.efi,10.1.1.2
	
	# later match overrides previous, keep ipxe script last
	# server address must be non zero, but can be anything as long as iPXE script is not fetched over TFTP
	dhcp-boot=tag:ipxe-ok,http://boot.ipxe.org/demo/boot.php,,0.0.0.1
	
	# To use internal TFTP server enabled these, recommended is otherwise atftp
	#enable-tftp
	#tftp-root=/tftproot/

This configuration is based on [[https://gist.github.com/NiKiZe/5c181471b96ac37a069af0a76688944d|this gist]]