Re: Disabling ip4 and IPV6 on F20RC1

Pavel Simerda <psimerda redhat com> writes:

there isn't any possibility to disable IPv6 link-local addresses. In
fact it's not properly supported even in the kernel.

echo 1 > /proc/sys/net/ipv6/conf/$DEVICE/disable_ipv6 works for me?

1) First of all it doesn't *specifically* disable kenrel link-local
addresses allocation but performs some magic to disable a couple of
IPv6 features at once. This wouldn't be a problem in the original
poster's case as he wants to disable IPv6 anyway.

That's sort of implied, isn't it?  You cannot remove all IPv6 LL
addresses from an interface without disabling IPv6. This is a protocol
requirement.  Ref e.g. RFC 4291:

   2.8.  A Node's Required Addresses

   A host is required to recognize the following addresses as
   identifying itself:

      o Its required Link-Local address for each interface..

2) But setting disable_ipv6 doesn't really work as expected. See [1]
and especially the note about disable_ipv6 below the table.

I read that note, but couldn't figure out what expectations that would
be. FWIW, disable_ipv6 works for me as well. That is:  The behaviour
matches my expectations.  Which are

  /proc/sys/net/ipv6/conf/$DEVICE/disable_ipv6 = 1
     => no IPv6 LL address on $DEVICE

  /proc/sys/net/ipv6/conf/$DEVICE/disable_ipv6 = 0
     => IPv6 supported, including an EUI-64 based LL address

  changing IFF_UP does not affect the above in any way

Are you sure this wasn't one of the bugs fixed by commit 73a8bd74e261
("ipv6: Revert 'administrative down' address handling changes.")?  It's
difficult to tell from the link you gave, because it just refers to an
unspecified "kernel".  Which could be a FreeBSD kernel for all I know


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