Journey of iPXE boot using IPv6

In IPv6 the boot path is always given as a URL in DHCPv6 option 59 So we need to run a DHCPv6 service for this

option dhcp6.bootfile-url code 59 = string;
option dhcp6.client-arch-type code 61 = array of unsigned integer 16;

# match arch to send correct booturl https://ipxe.org/cfg/platform#notes
if exists dhcp6.client-arch-type and
   option dhcp6.client-arch-type = 00:07 {
   option dhcp6.bootfile-url "tftp://[2001:db8::69]/snponly.efi";
}

subnet6 2001:db8::/64 {
   range6 2001:db8::ff00/120;
}

Debug DHCP server: dhcpd -6 -d -f brInt -cf /etc/dhcp/dhcpd6.conf Run the server and try booting but also check whats on the wire with: tcpdump -vni brInt port 547 tcpdump isn't verry good at expanding this data and only show that options exist, but not contents: (opt_59) Let's grab the actuall contents as well to verify what is sent: tcpdump -vni brInt -A port 547

No boot here, lets also grab TFTP transfers: tcpdump -vni brInt -A port 547 or port 69 There are requests, but not transfers...

Lets check that we have a tftp server running (this actually took a good while to figure out)

ss -lnu
State                      Recv-Q                     Send-Q                                                      Local Address:Port                                           Peer Address:Port
UNCONN                     0                          0                                                                 0.0.0.0:69                                                  0.0.0.0:*

We do, at port 69, but only on IPv4, that explains it,

After some resarch, it turns out that atftp dont have any IPv6 support, lets switch to a different server.

 /etc/init.d/atftp stop; emerge -c atftp; emerge -vk tftp-hpa

Modify /etc/conf.d/in.tftpd to set INTFTPD_PATH and add --secure Also update service start and start the service

rc-update del atftp
rc-update add in.tftpd
/etc/init.d/in.tftpd start

Ok thats better

ss -lnu
State                      Recv-Q                     Send-Q                                                      Local Address:Port                                           Peer Address:Port
UNCONN                     0                          0                                                                 0.0.0.0:69                                                  0.0.0.0:*
UNCONN                     0                          0                                                                       *:69                                                        *:*

I have not 100% been able to verify if radvd also requires AdvOtherConfigFlag on; it might be, espacially on newer firmware.

Some takebacks from this:

tcpdump don't know much about DHCPv6
Use -A to check packet contents when tcpdump fails decoding
Verify that services are actually listening on IPv6

There is a few things we can do to clean this up, and also improvements in conditional logic, which is a revisit

NiKiZe/README.md

Journey of iPXE boot using IPv6