IPV6INIT=no, but does anyway on local network

Robert Locke lists at ralii.com
Sat Oct 4 14:06:14 UTC 2008


On Sat, 2008-10-04 at 02:54 -0400, Gene Heskett wrote:
> On Saturday 04 October 2008, edwardspl at ita.org.mo wrote:
> >Hello,
> >
> >You are using IPv4 ( If IPv6 disabled )...
> >
> >Edward.
> >
> Agreed Edward, but when it doesn't show the ipv6 addresses at all, the 
> interface is brought up in milliseconds, as opposed to the 5 second lag it 
> has now.  That is the lag I would like to remove.
> 
> Thank you.
> 

Gene and Edward,

All IPV6INIT does in the ifcfg-* file is prevent the network script from
using IPv6.  Fortunately/unfortunately, you are, in fact, still loading
the kernel module, ipv6.ko.  If that module is loaded, you will get a
locally scoped IPv6 address which is seen in the output that Gene
supplied.

> >Gene Heskett wrote:
> >>Greetings;
> >>
> >>In /etc/sysconfig/ifcfg-eth0 I have the line as in the subject, but I note
> >>that bringing up eth0, at a fixed ipv4 address in the 192.168 block, there
> >> is about a 5 second pause doing it, and ifconfig does report what looks
> >> like valid ipv6 addresses for both eth0 and lo.
> >>
> >>eth0      Link encap:Ethernet  HWaddr 00:1F:C6:62:FC:BB
> >>          inet addr:192.168.71.3  Bcast:192.168.71.255  Mask:255.255.255.0
> >>          inet6 addr: fe80::21f:c6ff:fe62:fcbb/64 Scope:Link
> >>          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
> >>          RX packets:52899 errors:0 dropped:0 overruns:0 frame:0
> >>          TX packets:45100 errors:0 dropped:0 overruns:0 carrier:0
> >>          collisions:0 txqueuelen:1000
> >>          RX bytes:34184438 (32.6 MiB)  TX bytes:26737247 (25.4 MiB)
> >>          Interrupt:22 Base address:0xa000
> >>
> >>lo        Link encap:Local Loopback
> >>          inet addr:127.0.0.1  Mask:255.0.0.0
> >>          inet6 addr: ::1/128 Scope:Host
> >>          UP LOOPBACK RUNNING  MTU:16436  Metric:1
> >>          RX packets:6888 errors:0 dropped:0 overruns:0 frame:0
> >>          TX packets:6888 errors:0 dropped:0 overruns:0 carrier:0
> >>          collisions:0 txqueuelen:0
> >>          RX bytes:16987249 (16.2 MiB)  TX bytes:16987249 (16.2 MiB)
> >>
> >>
> >>How does one go about disabling that?
> 

To entirely stop any form of IPv6 addressing from appearing, you need to
block the module.  Traditionally that is done in /etc/modprobe.conf by
placing a line or lines of the form:

alias ipv6 off
alias net_pf_10 off

The second line may or may not be needed anymore.  I do not know if IPv6
is the "true cause" of your 5-second delay, but the line(s) in
modprobe.conf are a more complete way to stop IPv6 addressing from
appearing.

HTH,

--Rob





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