5.6, IPv6: is autoconf set by default?

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5.6, IPv6: is autoconf set by default?

Harald Dunkel-5
Hi folks,

AFAICS the old net.inet6.ip6.accept_rtadv was replaced with a
local "autoconf" flag for each interface. I wonder if autoconf
is set or cleared by default, if inet6 is configured for the
network interfaces and if net.inet6.ip6.forwarding is enabled?

Every helpful comment is highly appreciated
Harri

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Re: 5.6, IPv6: is autoconf set by default?

Henrik Friedrichsen
On Tue, Dec 30, 2014 at 06:16:04PM +0100, Harald Dunkel wrote:
> I wonder if autoconf
> is set or cleared by default, if inet6 is configured for the
> network interfaces and if net.inet6.ip6.forwarding is enabled?

It certainly doesn't seem to be enabled by default as I just had to
enable it to get an IPv6 assigned. This was on -CURRENt, though.

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Re: 5.6, IPv6: is autoconf set by default?

Kapetanakis Giannis
In reply to this post by Harald Dunkel-5
On 30/12/14 19:16, Harald Dunkel wrote:
> Hi folks,
>
> AFAICS the old net.inet6.ip6.accept_rtadv was replaced with a
> local "autoconf" flag for each interface. I wonder if autoconf
> is set or cleared by default, if inet6 is configured for the
> network interfaces and if net.inet6.ip6.forwarding is enabled?
>
> Every helpful comment is highly appreciated
> Harri

Not sure about autoconf but
you can check status of net.inet6.ip6.forwarding with
sysctl -a | grep net.inet6.ip6.forwarding

which is off by default.
You can enable it realtime with sysctl and make it permanent in
/etc/sysctl.conf

G

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Re: 5.6, IPv6: is autoconf set by default?

Harald Dunkel-5
In reply to this post by Henrik Friedrichsen
On 12/30/14 18:26, Henrik Friedrichsen wrote:
>
> It certainly doesn't seem to be enabled by default as I just had to
> enable it to get an IPv6 assigned. This was on -CURRENt, though.
>

My concern is about accepting foreign routing advertisements on a
gateway.


Regards
Harri

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Re: 5.6, IPv6: is autoconf set by default?

Sebastian Benoit
Harald Dunkel([hidden email]) on 2015.01.01 14:12:30 +0100:
> On 12/30/14 18:26, Henrik Friedrichsen wrote:
> >
> > It certainly doesn't seem to be enabled by default as I just had to
> > enable it to get an IPv6 assigned. This was on -CURRENt, though.
> >
>
> My concern is about accepting foreign routing advertisements on a
> gateway.

autoconf is only enabled if you do

  ifconfig <if> inet6 autoconf

otherwise, RAs will be ignored.

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Re: 5.6, IPv6: is autoconf set by default?

Harald Dunkel-3
On 01/07/15 23:38, Sebastian Benoit wrote:
>
> autoconf is only enabled if you do
>
>   ifconfig <if> inet6 autoconf
>
> otherwise, RAs will be ignored.
>

Thanx very much. I would suggest to mention the default in
ifconfig(8).

Regards
Harri

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Re: 5.6, IPv6: is autoconf set by default?

Sly Midnight
I am replying to this as I too would like some clarification as to the
difference between the two options {eui64|autoconf} for enabling the old
IPv6 behavior.

I typically read the man pages frequently and routinely and while
sometimes they are lacking on linux, I have found the man pages for
FreeBSD and OpenBSD to be very thorough.

So needless to say I initially thought it was a bug introduced into the
kernel when according to the man page all I had to do to re-enable IPv6
for a certain interface was call autoconf as an option (which made sense
to me).  This only worked enough to enable IPv6 addressing, but no
enough functionality to actually plumb up the necessary routes even for
the IP that was assigned and RA's were not being respected despite the
tuning of the appropriate sysctl.

It wasn't until I read else in the update changelog that someone else on
this list (I forget his name now and have deleted the email) the link to
said page where it said something conflicting to the man page.

There it said to use the eui64 option also with no mention of the
autoconf option.

So in one place it says to use one option with no mention of the other,
and then in the other place its the complete opposite with neither
clarifying what's the exact difference between the two, and when one
should be used over the other.

Reilly

On 01/08/2015 03:20 AM, Harald Dunkel wrote:

> On 01/07/15 23:38, Sebastian Benoit wrote:
>> autoconf is only enabled if you do
>>
>>   ifconfig <if> inet6 autoconf
>>
>> otherwise, RAs will be ignored.
>>
> Thanx very much. I would suggest to mention the default in
> ifconfig(8).
>
> Regards
> Harri

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Re: 5.6, IPv6: is autoconf set by default?

Florian Obser-2
On Thu, Jan 08, 2015 at 09:53:10AM -0500, Sly Midnight wrote:
> I am replying to this as I too would like some clarification as to the
> difference between the two options {eui64|autoconf} for enabling the old
> IPv6 behavior.

in ifconfig(8) we have:

     -inet6          Disable inet6(4) on the given interface and remove all
                     configured inet6(4) addresses, including the link-local
                     ones.  This is the default.  To turn inet6 on, use eui64,
                     use autoconf or assign any inet6 address.

[...]

     eui64   Fill the interface index (the lowermost 64th bit of an IPv6
             address) automatically.

[...]

     autoconf        Enable autoconfiguration.  Valid for ``inet6'' only.  If
                     autoconf is enabled router advertisements are accepted on
                     this interface and the kernel sends periodic router
                     solicitations from this interface.

------------------------------------------------------------------------

If you want the old behaviour of only having a link local address on
every interface:
        # ifconfig INTERFACE inet6 eui64
Usually you don't want / need that.

Configure a static ip:
        # ifconfig INTERFACE inet6 2001:DB8::23/64
you will get a link local address automatically, too.

Use a SLAAC ip:
        # ifconfig INTERFACE inet6 autoconf
you will get a link local address automatically, too.

--
I'm not entirely sure you are real.

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Re: 5.6, IPv6: is autoconf set by default?

Josh Grosse
On Thu, Jan 08, 2015 at 03:20:46PM +0000, Florian Obser wrote:

> [...]
>
>      eui64   Fill the interface index (the lowermost 64th bit of an IPv6
>              address) automatically.

But as I understand this, EUI64 isn't about a singular bit.  It's the
conversion of the 48 bit MAC address into a 64-bit value.

Perhaps the grammer could change for clarity?  I was confused until
I tested the option.

Index: ifconfig.8
===================================================================
RCS file: /cvs/src/sbin/ifconfig/ifconfig.8,v
retrieving revision 1.249
diff -u -p -u -p -r1.249 ifconfig.8
--- ifconfig.8 3 Dec 2014 21:30:30 -0000 1.249
+++ ifconfig.8 8 Jan 2015 21:23:04 -0000
@@ -1156,7 +1156,7 @@ Currently configured addresses will not
 invalid.
 .It Cm eui64
 Fill the interface index
-.Pq the lowermost 64th bit of an IPv6 address
+.Pq the lowermost 64 bits of an IPv6 address
 automatically.
 .It Cm pltime Ar n
 Set preferred lifetime for the address.

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Re: 5.6, IPv6: is autoconf set by default?

Sly Midnight
I will need to test this on a separate install of OpenBSD on my LAN as I
was just trying to get my one install that is used as my
firewall/gateway and IPv6 router to the public Internet from my private
LAN working again after the upgrade.

And when I initially used autoconf as an ifconfig option in the
interface's hostname files, I got the link local address as expected,
but any IPs setup on the machine were not routable to the local LAN it
was plumbed up on.  The implied route by the /64 prefix was just missing
and I knew no way to manually add that back (couldn't figure out the
appropriate route add syntax to do so).

Once I changed the option to eui64, I got almost the exact same behavior
save for the missing routes suddenly were there and everything else that
didn't work (due to the missing route) now worked.

Of course in this case, autoconf is likely inappropriate for this
particular machine as it's being used as a router and has
net.inet6.ip6.forwarding=1 which explicitly disables accepting and
honoring RAs.  But still the plumbing up of the link local addresses,
but without the route seemed to me like a bug.

Reilly

On 01/08/2015 04:25 PM, Josh Grosse wrote:

> On Thu, Jan 08, 2015 at 03:20:46PM +0000, Florian Obser wrote:
>
>> [...]
>>
>>      eui64   Fill the interface index (the lowermost 64th bit of an IPv6
>>              address) automatically.
> But as I understand this, EUI64 isn't about a singular bit.  It's the
> conversion of the 48 bit MAC address into a 64-bit value.
>
> Perhaps the grammer could change for clarity?  I was confused until
> I tested the option.
>
> Index: ifconfig.8
> ===================================================================
> RCS file: /cvs/src/sbin/ifconfig/ifconfig.8,v
> retrieving revision 1.249
> diff -u -p -u -p -r1.249 ifconfig.8
> --- ifconfig.8 3 Dec 2014 21:30:30 -0000 1.249
> +++ ifconfig.8 8 Jan 2015 21:23:04 -0000
> @@ -1156,7 +1156,7 @@ Currently configured addresses will not
>  invalid.
>  .It Cm eui64
>  Fill the interface index
> -.Pq the lowermost 64th bit of an IPv6 address
> +.Pq the lowermost 64 bits of an IPv6 address
>  automatically.
>  .It Cm pltime Ar n
>  Set preferred lifetime for the address.