[ipxe-devel] Fallback to IPv4 or disable IPv6

[Michael Brown]

On 01/11/2018 17:40, Anatoli Babenia wrote:
> My upstream provider doesn't support IPv6. No addresses are reachable.
> But my router still gives me an IPv6 address and is even able to resolve
> AAAA records. Being able to resolve IPv6 address iPXE thinks that it got
> IPv6 and fails, but it should try IPv4 instead.
> 
> Here is the log - https://github.com/antonym/netboot.xyz/issues/283
> 
> Is it possible to make current 133f fallback to IPv4 if IPv6 fetch fails?
> 
> Also, is there an option to disable IPv6 from Failsafe Menu? Manual
> network configuration doesn't help.

iPXE will query for AAAA records only if the DNS server address is 
itself an IPv6 address.  This is the heuristic we use to decide between 
IPv6 and IPv4 when a DNS name is used.

The best solution would be to fix your router to not provide an IPv6 
address, since IPv6 is not actually functional.  This should also speed 
up other computers on your network: they will no longer attempt IPv6 
first before timing out and falling back to IPv4.

If fixing your router is not an option, then you can use an embedded 
script fragment such as:

   dhcp
   set dns:ipv4 ${netX.dhcp/dns}

This will override any IPv6 nameserver address by explicitly setting the 
DHCPv4-acquired address as the "manual" nameserver address.

Michael