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Old 08-24-2010, 12:32 AM   #1
Registered: Aug 2009
Distribution: linux
Posts: 527

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blacklist ipv6 not sticking

hey thanks for stopping by.

So, here is what I tried:

Since I had no aliase in /etc/modprobe.d/, I made one. I have also added entries to blacklist.conf ( even tried blacklist with out the .conf ), added entry to sysctl.conf, and added a no load to my grub.conf ( /etc/default/grub). I am still seeing ipv6 in netstat but not when i check lsmod. Below are my entries:

cat /etc/sysctl.conf | grep ipv6
net.ipv6.conf.all.accept_redirects = 0
net.ipv6.conf.all.accept_source_route = 0
net.ipv6.conf.all.disable_ipv6 = 1
cat /etc/modprobe.d/blacklist 
blacklist ipv6
install ipv6 /bin/true
cat /etc/modprobe.d/blacklist.conf | grep ipv6
blacklist ipv6
install ipv6 /bin/true
lsmod | grep ipv6
cat /etc/default/grub | grep DEFAULT
GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 quiet splash"
Any ideas why I am still seeing service listing with ipv6?

thanks for the help
Old 08-24-2010, 01:26 AM   #2
John VV
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Registered: Aug 2005
Posts: 15,895

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it might help if you informed us as to what distro & version you are using
and is this a headless server ?

if not headless
are you using "network" or " networkmanager" service ?
how are you connecting to the net ?
wired ? - dsl , cable , dial up ?
wireless ?

most distros have a gui setting for this
but with out knowing what you are using .........

and a text only solution varies

RHEL / centOS / fedora do things one way

suse dose it different
ubuntu ? i do not know
1 members found this post helpful.
Old 08-24-2010, 01:44 AM   #3
Registered: Aug 2009
Distribution: linux
Posts: 527

Original Poster
Rep: Reputation: 51
sorry, I thought /etc/default/grub was a debian -ubuntu thing. Not a headless server. Just plain old ubuntu desktop running gnome ( does that really have anything to do with how ipv6 loads during boot). What I don't understand is how ipv6 can even load up if I have it blacklisted in the grub line. Any help would be appreciated.

Last edited by mrmnemo; 08-24-2010 at 01:50 AM.
Old 08-24-2010, 08:27 AM   #4
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Registered: May 2003
Location: London, UK
Distribution: Debian "Jessie"
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You didn't tell us which version of "ubuntu" you are running, but my guess is 10.04 because in this release handling of IPV6 was moved from a module, into the kernel.

So to disable it add ipv6.disable=1 to your kernel boot line at boot time, or do it in grub by setting the line
in /etc/default/grub and then runnning update-grub

Last edited by tredegar; 08-24-2010 at 08:28 AM.
1 members found this post helpful.
Old 08-24-2010, 10:35 AM   #5
Registered: Aug 2009
Distribution: linux
Posts: 527

Original Poster
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Hey thanks, Tredgar!! I forgot to update grub and initramfs. It worked!! Its funny how the little things make a all the difference in the world. I would have thanked you via the post; however, the link to do so is not showing up for me anymore.
Old 08-25-2010, 09:43 PM   #6
Registered: Aug 2009
Distribution: linux
Posts: 527

Original Poster
Rep: Reputation: 51
Just wanted to close this up.

As per tredegar's advice, ran
sudo update-grub && update-initramfs -u

Worked great! I find it odd that blacklisting the module vie modprobe.d/blacklist.conf is not working though. I find it even odder that AFTER bnlacklisting via modprobe.d/blacklist.conf, running lsmod | grep ipv6 ( and getting no results ) that I still had services listening on ipv6. Coul;d anyone tell me why that is?

EDIT: Just re-read tredegar's post and notticed that ipv6 is now part of the kernel. Thanks again tredegar!!

Last edited by mrmnemo; 08-25-2010 at 09:44 PM.



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