How to switch off IPv6 on RPi3?

[carriba]

Thank you all for the suggestions provided, and indeed it helps to disable IPv6 completely and remove the module from memory as follows:

Contents of the /etc/modprobe.d/ipv6.conf configuration file:

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alias net-pf-10 off
alias ipv6 off
options ipv6 disable_ipv6=1
blacklist ipv6

After a reboot, firing the command "lsmod" shall show no line entry denoting to "ipv6.", and the same shall also be for the command "ifconfig".

Optionally and if required, add in /boot/cmdtline.txt the parameter:

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ipv6.disable=1

It works also for the latest April 2017 Raspbian image with kernel version 4.9.22-v7+.

[DavidS.]

Hiho.
I have some questions about this topic. I want to work with ipv6 on my pi.

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Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      -
tcp        0      0 127.0.0.1:6010          0.0.0.0:*               LISTEN      -
tcp        0      0 0.0.0.0:8123            0.0.0.0:*               LISTEN      -
tcp6       0      0 :::80                   :::*                    LISTEN      -
tcp6       0      0 :::22                   :::*                    LISTEN      -
tcp6       0      0 ::1:6010                :::*                    LISTEN      -

Whats the meaning of the numbers 80, 22 and 6010 ?

[Martin Frezman]

Whats the meaning of the numbers 80, 22 and 6010 ?

They are port numbers of existing connections that you have to your Pi.

80 is HTTP (web)
22 is ssh (terminal)
6010 is X windows - display 10 - which is generally connected with an ssh connection (with the -X or -Y command line option).

[lilbran]

Yes, it is built into the kernel, not as a module.

To disable it completely just add this to /boot/cmdline.txt

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ipv6.disable=1

Worked perfectly and was finally able to get my RPi to update! Thank you!!

[Tomo2k]

Excellent, thanks.

As to "Why disable IPv6?"

apt-get seems to prefer IPv6 mirrors if they are listed.

My ISP doesn't support IPv6, so I can't get to any of those mirrors, and thus apt-get upgrade fails.
Disabling IPv6 appears to force apt to pick an IPv4 mirror.

It'd be lovely if my ISP could add support for IPv6, however the majority of UK ISPs don't and it's clearly going to be a long time before they do.
My guess is that they have a large installed base of ancient routers that they can't upgrade, and don't want to spend the money replacing.

[rpdom]

This page is also relevant for Raspbian, even though it says it is for Ubuntu. It gives a method of disabling IPv6 for just apt or for the whole system. It doesn't require changes to cmdline.txt.

[ignazioc]

This post helped me a lot.
I had to disable IPV6 on my raspberryPI because `apt-get update` was not working properly, blocked always to 0%

Can someone explains me the reason why?

[mk6032]

I turned it off using "/etc/sysctl.conf", by adding the line "net.ipv6.conf.all.disable_ipv6 = 1"

That resulted in no ipv6 address:

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eth0      Link encap:Ethernet  HWaddr b8:27:eb:4f:95:d6
          inet addr:192.168.0.6  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:75072 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4621 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:4554883 (4.3 MiB)  TX bytes:801499 (782.7 KiB)

But netstat still shows it

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>$ netstat -lnpt
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      -
tcp6       0      0 :::22                   :::*                    LISTEN      -

Some daemons will listen to ipv6 by default. In your example there its sshd. NTP, named, etc. may also listen on ipv6 by default, and you may need to edit the appropriate /etc/default/ file to change the start options for the daemon (e.g. -4 option for sshd).