dhcpcd-discuss

> On Jan 31, 2016, at 3:47 AM, Roy Marples <roy@xxxxxxxxxxxx> wrote:
> 
> On 2016-01-31 04:04, Nick Williams wrote:
>>> I'll pick that out :)
>>> What is an important bug?
>> I guess what I was asking here is, “is there a version before which
>> DHCPv6 and/or prefix delegation just don’t work at all because of
>> some major bug that was fixed?” I get that we need to perform
>> thorough testing, etc.
> 
> OK, here's a little bug for you :)
> There appears to be an issue with assigning delegated prefixes to interfaces with a prefix length of 64 or greater right now.
> This issue appears to have always been there and I'm working on a fix in my spare time.
> As no-one has noticed it recently (although it could also be Peng's issue) I assume it's not urgent.
> However, it c
> 
> There is also an issue where the config is not working for multiple interfaces to delegate to.
> This issue appears to have been recently introduced, but I can't say from which version.

Good to know. I’ll keep an eye on these things.

>> But, since we’re looking at having to package
>> dhcpcd ourselves for our version of Debian, it would save me time if I
>> knew that there’s no point in trying anything before version X.
> 
> This is why I provide a list of important changes with each release to this mailing list.
> You can read the archives here:
> http://roy.marples.name/archives/dhcpcd-discuss/
> 
>> That aside, I have a couple more questions:
>> 1) What’s the point of config options “ipv4” / “ipv6” in
>> comparison to / conjunction with “dhcp” / “dhcp6” (slash their
>> “noipv4,” etc. companions)? Why would you use just “ipv4” or
>> just “dhcp” or both “ipv4” and “dhcp”? I read this [1]
>> documentation as well as I could, but that just stuck out to me as not
>> making sense.
> 
> IPv4 also always static IP assignment, ARP ing profiles and IPv4LL support - not just dhcp.
> IPv6 also has RS/RA - not just dhcpv6.

Understood. So “noipv6,” for example, would disable DHCPv6, IPv6RS, and IPv6 RA Autoconf. Given that, I think the below configuration should effect the narrative following it. Can you confirm that I have the right understanding now?

This:

allowinterfaces eth0 eth1
noipv4
noipv6
interface eth0
ipv4
interface eth1
ipv6
ia_na 1
ia_pd 2 eth2 eth3 eth4

Does this:
 - Enable dhcpcd to touch only eth0 and eth1 (except if delegating prefixes with PD)
 - Disables IPv4 / DHCP / ARP / IPv4LL for all interfaces unless explicitly enabled
 - Disables IPv6 / DHCPv6 / IPv6RS / IPv6 RA Autoconf for all interfaces unless explicitly enabled
 - Starts a config for eth0
 - Re-enables only IPv4 / DHCP / ARP / IPv4LL for eth0
 - Starts a config for eth1
 - Re-enables only IPv6 / DHCPv6 / IPv6RS / IPv6 RA Autoconf for eth1
 - Tells dhcpcd to request a single normal IPv6 address for eth1
 - Tells dhcpcd to request an appropriately-large prefix on eth1, split it up, and delegate /64 prefixes from it to eth2, eth3, and eth4.

>> 2) What will “allowinterfaces" do if you pass to it a non-existent
>> interface?

> 2 If allowinterfaces is set, each interface discovered must match the pattern passed to fnmatch(3)
> 3 Because fnmatch(3) states you are allowed to use wildcards it follows that an actual pattern doesn't exit but what it can match will exist
> 4 Therefore, if allowinterfaces has a pattern that does not exist, it's not an error.

Excellent. Thanks.

Nick