[11.2] IPv6 is not Disabled!?

English Network/Internet
#1

Hi,

I’m running a clean install of openSUSE 11.2 and have discovered that IPv6
is not disabled even though I have done the following:

  1. During the install I set IPv6 to Disabled

  2. Post install I set the network management method to Traditional with
    ifup. The option for Enable IPv6 was disabled, however to make sure that the
    system would get properly set up I enabled it and then disabled it.

  3. Also while in the network configuration I noticed that the DHCP client
    option was set to both IPv4 and IPv6. (This is probably a bug as it makes no
    sense to have the dhcp client for IPv6 enabled if there is no IPv6 running.)
    So I changed it to IPv4 only for both the wired and wireless interfaces.

After rebooting no change occured - IPv6 was still running and IPv6 addy’s
were still being assigned to all network interfaces.

Googling for answers has not yet gotten me anywhere…well that is not
entirely true…I have found out that there is no longer an
/etc/modprobe.conf file with settings to control IPv6.

Anyone care to hit me up the side of the head with a clue stick? I’m no
expert and probably just missed something obvious.

Thanks,

Ron

#2

What do you see here:
Disable IPv6 - openSUSE Forums

#3

> Anyone care to hit me up the side of the head with a clue stick? I’m no
> expert and probably just missed something obvious.

i have been trying to follow this with some interest and have
copy/pasted the following from several different sources…i haven’t
yet installed 11.2 so i have NO idea if any of it will work…so,
beware! (and good luck–recommend you read all before trying any)

Open Yast -> Network Devices ->Network Settings and in Global Options
tab Uncheck Enable IPv6

in firefox type ‘about:config’ in the address bar, press enter then
search for 'disable ipv6. Double click to set value to true if
currently set to false.

then i saw:

“I had disabled IPv6 support in YAST but it doesn’t clean up the
/etc/hosts file. I deleted all of the IPv6 info in that file and made
sure the 127.0.0.1 address had localhost added.”
http://forums.opensuse.org/showthread.php?t=402048
like:

IP-Address Full-Qualified-Hostname Short-Hostname

127.0.0.1 localhost

special IPv6 addresses

in http://forums.opensuse.org/showthread.php?t=402048

#::1 localhost ipv6-localhost ipv6-loopback

#fe00::0 ipv6-localnet

#ff00::0 ipv6-mcastprefix
#ff02::1 ipv6-allnodes
#ff02::2 ipv6-allrouters
#ff02::3 ipv6-allhosts
#127.0.0.2 linux103-32.texan linux103-32

then:
for Opera, but maybe all??

Short version: try turning on EnableHostNameWebLoookup
(opera:config#Network|EnableHostNameWebLookup), and if that doesn’t
work, turn off IPv6. For Ubuntu this is
https://help.ubuntu.com/community/WebBrowsingSlowIPv6IPv4

sudo sh -c ‘echo blacklist ipv6 >> /etc/modprobe.d/blacklist.local’

sudo reboot

then:

with 11.2: Found out that ipv6 is no longer a module, it is in the
kernel, so you can administratively disable with a kernel option in
grub’s menu.lst of ipv6.disable=1 but individual applications can
still send out v4 and v6 queries. In my case yast2 -> software ->
online update still sends out both, until I find out how to disable.

–
palladium

#4

Ouch! if ipv6 is in the 11.2 kernel as palladium said in next post I will NOT be continuing with newer openSUSE versions. 6 months of fighting ipv6 cr** on my system was enough. I responded to you because I clicked the link you gave and each time I click it I get firefox is not responding! then it closes. That’s the first time I’ve ever had an error like this in firefox!

#5

palladium wrote:

> i have been trying to follow this with some interest and have
> copy/pasted the following from several different sources…i haven’t
> yet installed 11.2 so i have NO idea if any of it will work…so,
> beware! (and good luck–recommend you read all before trying any)

Nope, none of it works.

> --------------------------------------------------------------------
> Open Yast → Network Devices ->Network Settings and in Global Options
> tab Uncheck Enable IPv6
>
As I said I had already done this. And just to confirm I also checked the
modprobe file (now /etc/modprobe.d/50-ipv6.conf in 11.2) and it contains the
correct entry : install ipv6 /bin/true

> in firefox type ‘about:config’ in the address bar, press enter then
> search for 'disable ipv6. Double click to set value to true if
> currently set to false.
>

This helps firefox but does nothing for the system and any other apps, eg
vmware workstation, opera.

>
> -------------------------------------
> then i saw:
>
> “I had disabled IPv6 support in YAST but it doesn’t clean up the
> /etc/hosts file. I deleted all of the IPv6 info in that file and made
> sure the 127.0.0.1 address had localhost added.”
> http://forums.opensuse.org/showthread.php?t=402048
> like:
> # IP-Address Full-Qualified-Hostname Short-Hostname
> #
>
> 127.0.0.1 localhost
>
> # special IPv6 addresses
> # in http://forums.opensuse.org/showthread.php?t=402048
> #::1 localhost ipv6-localhost ipv6-loopback
> #
> #fe00::0 ipv6-localnet
> #
> #ff00::0 ipv6-mcastprefix
> #ff02::1 ipv6-allnodes
> #ff02::2 ipv6-allrouters
> #ff02::3 ipv6-allhosts
> #127.0.0.2 linux103-32.texan linux103-32
>

It is true that /etc/hosts is not modified to remove/disable the ipv6 host
entries. But commenting them out does not affect whether or not ipv6 is
loaded and bound to your network interfaces. So apps still suffer.

>
> -------------------------------------
> then:
> for Opera, but maybe all??
>
Opera does not support disabling ipv6. You have to disable ipv6 at the
network layer on the host, which is of course what I am trying to do.

> Short version: try turning on EnableHostNameWebLoookup
> (opera:config#Network|EnableHostNameWebLookup), and if that doesn’t
> work, turn off IPv6. For Ubuntu this is
> https://help.ubuntu.com/community/WebBrowsingSlowIPv6IPv4
>
> sudo sh -c ‘echo blacklist ipv6 >> /etc/modprobe.d/blacklist.local’
>
> sudo reboot
>
> -------------------------------------
> then:
>
> with 11.2: Found out that ipv6 is no longer a module, it is in the
> kernel, so you can administratively disable with a kernel option in
> grub’s menu.lst of ipv6.disable=1 but individual applications can
> still send out v4 and v6 queries. In my case yast2 → software →
> online update still sends out both, until I find out how to disable.

An even better method than editing your grub menu.lst is to add an entry to
your /etc/sysctl.conf file:
net.ipv6.conf.all.disable_ipv6 = 1

You can test this without rebooting (in a console do the following):

  1. First check the current value, enter:

cat /proc/sys/net/ipv6/conf/all/disable_ipv6

The value should be 0 which is the default - meaning that ipv6 is enabled by
default.

  1. Now change the value by executing the following command as root:

echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6

  1. Restart network services, again as root:

rcnetwork restart

  1. Check your config now by entering, as root:

ifconfig

There should no longer be any IPv6 address’s configured for any interface.

Again, o make this permanent edit /etc/sysctl.conf by adding this line:
net.ipv6…conf.all.disable_ipv6 = 1
Cheers,

Ron

PS. This is a bug in the opensuse yast and install routines as they should
put the proper entry in either menu.lst or preferably in /etc/sysctl.conf.

#6

techwiz03 wrote:

>
> caf4926;2072485 Wrote:
>> What do you see here:
>> ‘Disable IPv6 - openSUSE Forums’ (http://tinyurl.com/ygjpb3t)
>
> Ouch! if ipv6 is in the 11.2 kernel as palladium said in next post I
> will NOT be continuing with newer openSUSE versions. 6 months of
> fighting ipv6 cr** on my system was enough. I responded to you because I
> clicked the link you gave and each time I click it I get firefox is not
> responding! then it closes. That’s the first time I’ve ever had an error
> like this in firefox!
>
>
Hi, OP here - please check my response to Palladium for how to properly
disable ipv6.

Two things you need to realize about this change:

  1. It is not in the 11.2 kernel - because there is no such thing as an 11.2
    kernel. There is the opensuse 11.2 distribution which ships with kernel
    version 2.6.31.5. It is the Linux kernel which has IPv6 support compiled in.

  2. IPv6 has been supported in openSUSE prior to v11.2. The previous versions
    use a Linux kernel that does not have ipv6 compiled into the kernel. Instead
    they load ipv6 as a loadable module. For these versions of openSUSE the
    standard method of disabling ipv6 worked just fine. These old methods no
    longer apply to ANY distro using the Linux kernel higher than 2.6.28 (I
    think that is when ipv6 entered the kernel).

Also your issue with firefox not loading that page that caf4296 refers to
has nothing to do with this discussion - except that I sense that you are
very vexed by ipv6 - and I don’t blame you :wink:

So, no matter what distro you use if it has a kernel newer that 2.6.28 then
you will be dealing with the ipv6 crap. Fortunately openSUSE is a great
distro and it is easy to make ipv6 go away.

Cheers,

Ron

#7

caf4926 wrote:

>
> What do you see here:
> ‘Disable IPv6 - openSUSE Forums’ (http://tinyurl.com/ygjpb3t)
>
>
I see alot of stuff that I tried before coming here to ask my question. Was
I supposed to see something else? (Sorry if I am being dense…).

Anyways, I found the problem and the solution. Please read my response to
Palladium.

Cheers,

Ron

#8

This should be in a sticky or tips and tricks for sure. Are they working a cure for yast-network? Because that’s what hung me out to dry when I installed 11.1 Yast made entries into obscure files about ipv6 so none of my network hardware would connect.

had to do a search of entire system and edit/remove all references to ipv6 to disable it so I could to Forums.

#9

Thanks for this tip Ron Neilly.

Worked great for me.:good:

#10

Ron Neilly wrote:

> palladium wrote:
>
>> i have been trying to follow this with some interest and have
Thank Ron, I’ll try this later today. I know my ISP does not support ipv6
yet. Hope this helps my slow downloads and over network slowness.
> PS. This is a bug in the opensuse yast and install routines as they should
> put the proper entry in either menu.lst or preferably in /etc/sysctl.conf.

–
Russ
[openSUSE 11.2 (2.6.31.5-0.1-desktop, x86_64] KDE 4.3.3 release 1, Intel
Core 2 Dual E7200, 4 GB DDR III, GeForce 8400 GS, 320GB Disc (2)

#11

I had an issue with IPv6 and a bridged connection. Followed advice of buckesfeld and eventually got rid of it.

See this thread: Undo bridged connection and IPv6 - openSUSE Forums

#12

> add an entry to your /etc/sysctl.conf file:
> net.ipv6.conf.all.disable_ipv6 = 1
>
> You can test this without rebooting (in a console do the following):
>
> 1. First check the current value, enter:
>
> cat /proc/sys/net/ipv6/conf/all/disable_ipv6
>
> The value should be 0 which is the default - meaning that ipv6 is enabled by
> default.
>
> 2. Now change the value by executing the following command as root:
>
> echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6
>
> 3. Restart network services, again as root:
>
> rcnetwork restart
>
> 4. Check your config now by entering, as root:
>
> ifconfig
>
> There should no longer be any IPv6 address’s configured for any interface.
>
> Again, o make this permanent edit /etc/sysctl.conf by adding this line:
> net.ipv6…conf.all.disable_ipv6 = 1
>
> PS. This is a bug in the opensuse yast and install routines as they should
> put the proper entry in either menu.lst or preferably in /etc/sysctl.conf.

ok, so you are submitting a bug report to the developers to change
YaST and the install routines, right?

and, a forum moderator should should be move/copy the above (at least) to:

http://forums.opensuse.org/new-user-how-faq-read-only/unreviewed-how-faq/
and/or
http://forums.opensuse.org/new-user-how-faq-read-only/

comments from others?

palladium

#13

I did a fresh install of openSUSE 11.2 on my machine and found that after the install internet access was incredibly slow all of a sudden. After googling I found that having IPv6 enabled was probably the cause. So I tried to disable it. I found that disabling IPv6 in yast2 -> “Network Settings” didn’t work because that part of yast2 is still under the assumption that ipv6 is a kernel module, which is no longer the case in a 2.6.31 kernel. So I did some more googling and found that adding “ipv6.disable=1” to the kernel boot parameters in /boot/grub/menu.lst did the trick. After rebooting I found that ipv6 had disappeared: the inet6 entry in the ifconfig output was gone, and also “ls /proc/sys/net/” no longer showed an ipv6 entry. However, to my dismay I noticed that internet access was still suffering from long timeouts. I think that these are due to the fact that the application is still trying to set up an IPv6 connection, e.g.:

pvh@dogbert> time ssh -4 helios date
Sun Dec 13 17:24:47 UTC 2009
0.004u 0.010s 0:00.76 1.3%      0+0k 0+0io 0pf+0w
pvh@dogbert> time ssh helios date
Sun Dec 13 17:24:59 UTC 2009
0.007u 0.010s 0:10.37 0.0%      0+0k 0+0io 0pf+0w

As you can see, when I force an IPv4 connection with the -4 flag, connecting to the remote host helios is quick, but when I don’t add the flag there clearly is a 10 second timeout, which I interpret as that ssh is still trying to set up an IPv6 connection to the remote host. All programs that go on the internet seem to be suffering from this problem: ssh, curl, firefox, thunderbird, etc, etc… This doesn’t make any sense to me since (as far as I can tell) IPv6 is disabled. So what am I missing here? Why do all these programs still try to set up an IPv6 connection? Or is the timeout due to another problem? In short, how do I get rid of these annoying timeouts?