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Woflie
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Disabling IPV6, yep that old Chestnut again.. IS SOLVED

Sat Dec 31, 2016 11:35 am

Only three days out of the box and I already feel like I know this Pi thing inside out having already surmounted several problems assisted by Mr DuckDuckgo. However, the Pi is made of sterner stuff and continues to thwart my puny efforts in getting it online from Boot up.
The reason this Pi (Debian) won't connect to the internet is this damn IPV6 enabled by default.. It will connect to the home LAN and file transfer programs, everything works fine, but not for anything outside in the WAN, ie the internet.

And I'm reluctant at this stage to reconfigure my home network and items just to accommodate one item with a stupid config..

M searches show that entering the line " net.ipv6.conf.all.disable_ipv6 = 1 " into the /etc/sysctl.conf file has worked for many others and so those help threads end there.. But in this case doesn't. so I suspect that somewhere in another config file that is run afterwards, there may be another line re-enforcing the use of IPV6..

I can disable it with the line " sudo dhclient -4 -v wlan0 " to force the use of IPV4, then everything works as it should, but for this sesson only.

So the question is.. Where should I look next to force the use IPV4 over IPV6?
Last edited by Woflie on Thu Jan 05, 2017 7:39 pm, edited 1 time in total.
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Wolfie
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Martin Frezman
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 11:48 am

You won't get any help here, because the regulars here are tied to the religion that a) ipv6 is good and b) it is here to stay and you must accomadate yourself to that fact.

Much like what they say about "systemd".

Also, if the "supported" ways of turning it off don't work, they're not going to go into the "non-supported/hackish" ways.

Personally, I would put that command that you found to work into your /etc/rc.local file and be done with it.

P.S. I know of what I speak, since I once had to install Debian (on x86) via the network and ran into trouble with ipv6 killing my connection (during the install). I eventually figured out a hackish way to kill it (ipv6) and the install then worked. It was a painful experience.
If this post appears in the wrong forums category, my apologies.

mfa298
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 11:55 am

If you don't have IPv6 enabled on your lan then your Pi shouldn't have a global IPv6 address so won't use IPv6 for anything. Most systems these days (and have done for a while) default to this setup.

If you look at an ifconfig output and only see a line like

Code: Select all

inet6 addr: fe80::ba27:ebff:fe4f:64bf/64 Scope:Link
then that means there's no IPv6 configured on the local network and the Pi won't use IPv6 for anything outside the local lan (it may use IPv6 for something local if it knows how to talk to it)

If you have a like more like

Code: Select all

inet6 addr: 2001:db8:b33f:cafe:ba27:ebff:fe4f:64bf/64 Scope:Global
(The key parts are that it says Scope:Global and almost certainly starts with a 2) then something on your local lan is acting as an IPv6 router.

Unless you have a global IPv6 address and you are trying to connect to something that advertises an IPv6 address then you should be using IPv4 without having to change any configuration.

You may find it useful to try some standard network tests such as

Code: Select all

traceroute -n 8.8.8.8
traceroute google-public-dns-a.google.com.
both of which will only use IPv4 regardless of whether IPv6 is configured or not.

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Woflie
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 12:05 pm

Yep it was because I couldn't get the RDP package to download that I had to pull my hair out finding the cause.

Haha, so there is an IPV6 clique eh? :D I wonder just how many people could config their home router n stuff for IPV6?
Ah well each to their own.

And I daresay I'll figure it out for myself eventually, so come and ask me folks..

On our Bikey Forums, we pour scorn on anyone wanting to take a rare UK bike and make it into a "special" ie non standard, but nontheless will help with tech advice and/or parts or even hands on help them achieve just that.. different worlds I suppose.

But thanks for the heads up Image
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rpdom
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 12:18 pm

Woflie wrote:Haha, so there is an IPV6 clique eh?
No, that's just one person's opinion. Most people don't use IPV6. Eventually we will have to, but that day is still a few years away.
I wonder just how many people could config their home router n stuff for IPV6?
Either the router already supports it or you can do some magic with an IPV6 tunnel to an outside server. I don't bother.
Again, it will have to happen one day.

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Woflie
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 12:43 pm

Hi MFA.. I have to admit that while I understand IPV4 fairly well, IPV6 workings are still a mystery and in the realms of witchcraft.. This is my first encounter.

I did an(other) ifconfig to check those Wlan0 details.

[attachment=1]ifconfig.jpg[/attachment]

Hmmm... I have forced the (--.15) address on Wlan0 by Router/switch DHCP and it sticks to that address even when connected by Eth0 which should then be a different DHCP address (--.5). But the line you quoted is absent, does that mean the there is no IPV6 being used?
So it appears to have all the IPV4 settings necessary, yet I still get this..

[attachment=0]unreachable.jpg[/attachment]

In which case I'm confused since I copied theimage using remote desktop from the PC (over the local network) and forcing an IPV4 manually (as above) makes it work over the internet too. Computers eh?
Attachments
unreachable.jpg
unreachable.jpg (38.81 KiB) Viewed 5594 times
ifconfig.jpg
ifconfig.jpg (54.79 KiB) Viewed 5666 times
Last edited by Woflie on Sat Dec 31, 2016 1:05 pm, edited 2 times in total.
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Wolfie
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Woflie
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 12:56 pm

But at this early stage and in the absence of other information, I have to accept what I hear as being "how it is".. sorting "wheat from chaff" comes with experience.

I hold no judgement on information received. I'm just glad that someone out there takes the time to help others climb the knowledge ladder.

Thanks so far guys.
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mfa298
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 1:50 pm

Woflie wrote:But at this early stage and in the absence of other information, I have to accept what I hear as being "how it is".. sorting "wheat from chaff" comes with experience.

I hold no judgement on information received. I'm just glad that someone out there takes the time to help others climb the knowledge ladder.

Thanks so far guys.
Try the traceroute commands I gave earlier as that will test your routing and dns setup, I suspect there's an issue with one of those.

The lack of Scope:Local in your ifconfig might suggest that you've managed to disable all IPv6 connectivity.
Woflie wrote:
Haha, so there is an IPV6 clique eh? :D I wonder just how many people could config their home router n stuff for IPV6?
Ah well each to their own.
As rpdom IPv6 is going to happen (it's been slowly building up for a number of years, a lot of big sites started running IPv6 in 2012 and it's been building since then). For the majority of users who just use the router provided by the ISP IPv6 will likely just roll out an updated firmware and config that enables IPv6 (I think Sky in the UK have been starting that process already).

For the most part IPv6 and IPv4 will co-exist quite happily and the system will use whichever makes most sense (usually with a preference for IPv6 if both are available).

fred44nl
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 2:11 pm

as you can see, I have ipV6 up and running.
don't know if I can be of any help :)
pls note, I'm completely headless.
Attachments
Schermafbeelding 2016-12-31 om 15.03.50.jpg
Schermafbeelding 2016-12-31 om 15.03.50.jpg (59.63 KiB) Viewed 5507 times
headless RPi 3B running from usbhdd.

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Woflie
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 2:19 pm

Ah yes sorry, I missed that bit...

[attachment=0]traceroute google.jpg[/attachment]

So, no external connectivity shown.
Attachments
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Wolfie
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Woflie
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 2:22 pm

I am using this Pi with no Keyboard, mouse or monitor at the moment. it may or may not stay that way.
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boyoh
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 2:36 pm

Hy Up Lad from Yorkshire
You'v cracked the inside of the Pi . In three day's. Now lets see what you can crack on the outside of the Pi in three days
With hardware
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fred44nl
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 2:40 pm

your screens don't show any sign of ipV6
so, you don't have it, I presume.
I know my modem/router provides ipV6 connections, and so does my RPi3

this is my routing table:

Code: Select all

[email protected]:~ $ sudo route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.11.1    0.0.0.0         UG    202    0        0 eth0
192.168.11.0    0.0.0.0         255.255.255.0   U     202    0        0 eth0
headless RPi 3B running from usbhdd.

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Woflie
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 3:07 pm

I did the dhclient again and forced IPV4.

Now I get the full route to Google.com in 9 hops, but the details for wlan0 haven't altered at all (apart from the packets sent/received of course).

This is what it said at the dhclient command.. don't know if this helps.

[attachment=0]dhclient.jpg[/attachment]

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Wolfie
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fred44nl
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Re: Disabling IPV6, yep that old Chestnut again..

Sat Dec 31, 2016 3:37 pm

I have basically the same output from dhclient.
the main difference is, that mine reports for eth0, which is logical as I am using an utp-cable.
dhclient does not mention ipV6 at all, so probably that command works for ipV4 only.

Code: Select all

[email protected]:~ $ sudo dhclient  -v
Internet Systems Consortium DHCP Client 4.3.1
Copyright 2004-2014 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth0/b8:27:eb:b9:bc:51
Sending on   LPF/eth0/b8:27:eb:b9:bc:51
Sending on   Socket/fallback
DHCPREQUEST on eth0 to 255.255.255.255 port 67
DHCPACK from 192.168.11.1
RTNETLINK answers: File exists
bound to 192.168.11.21 -- renewal in 1573 seconds.
[email protected]:~ $ 
headless RPi 3B running from usbhdd.

Marlor
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Re: Disabling IPV6, yep that old Chestnut again..

Sun Jan 01, 2017 2:15 pm

Open /etc/modprobe.d/ipv6.conf
Delete everything and add:

Code: Select all

blacklist ipv6
viewtopic.php?p=985755#p985755

Heater
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Re: Disabling IPV6, yep that old Chestnut again..

Sun Jan 01, 2017 2:24 pm

I think I have missed a point here.

Could somebody explain exactly why any one would need to disable IPv6?

I have IPv6 working on my home LAN. I did nothing to enable or configure that. Except my router Dlink router runs OpenWRT.

I can access IPv6 sites from my Windows 10 machine. According to http://test-ipv6.com/ I'm all IPv6 ready.

Meanwhile any Pi I put on this LAN just works without any messing about disabling IPv6 or whatever. ping and ping6 both work just fine.

In short, having IPv6 working has never caused me a problem. I have never had to think about it.

So what's the issue actually?

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Re: Disabling IPV6, yep that old Chestnut again..

Sun Jan 01, 2017 2:28 pm

Heater wrote:I think I have missed a point here.

Could somebody explain exactly why any one would need to disable IPv6?
Read the first para of the OP again. I don't know if IP6 is the problem in this case, but disabling it removes one possibility of error.
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Re: Disabling IPV6, yep that old Chestnut again..

Sun Jan 01, 2017 2:41 pm

I've no idea why you need to disable IPv6.

This works: http://askubuntu.com/questions/440649/h ... untu-14-04
Last edited by DougieLawson on Sun Jan 01, 2017 3:35 pm, edited 1 time in total.
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nastybuttler322
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Re: Disabling IPV6, yep that old Chestnut again..

Sun Jan 01, 2017 2:43 pm

change your wifi password and try connecting with your pi before the other stuff.

Heater
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Re: Disabling IPV6, yep that old Chestnut again..

Sun Jan 01, 2017 2:43 pm

davidcoton,

It does not help to read it yet again. The first paragraph of the OP says nothing of import.

The rest of the OP states: "The reason this Pi (Debian) won't connect to the internet is this damn IPV6 enabled by default..".

Which tells me:

1) His Pi cannot reach the net correctly. OK.

2) The reason given is IPv6. Which seems unlikely.

3) The "damn" implies there is something bad about IPv6.

Having read the whole thread I still don't understand why his network connectivity is busted or what IPv6 has to do with it.

Out of curiosity, and in case I ever run into this issue, I'd like to know where the problem really is.

Heater
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Re: Disabling IPV6, yep that old Chestnut again..

Sun Jan 01, 2017 2:51 pm

Further...

Some people here have suggested that IPv6 is a bad idea.

Why is that?

Personally I love the idea of being able to reach anything on my home network without needing NAT and such messing around. I want all my devices to have public, static, IP addresses. Like the good old days :)

Philosophically I want the net to be a network of peers. Sure a private local LAN is a good idea in many cases. But I'd rather that was at my choice rather than having my ISP or mobile provider putting me behind their wall.

I don't have much idea of the underlying mechanics of IPv6 so I can't comment on it's technical merits.
Last edited by Heater on Sun Jan 01, 2017 2:55 pm, edited 1 time in total.

Martin Frezman
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Re: Disabling IPV6, yep that old Chestnut again..

Sun Jan 01, 2017 2:54 pm

Short answer: If it causes a problem, it is a problem.

See my earlier post for a situation in which it was a problem.

Also:
1) Clearly, it must work for some (perhaps even most) people under some (perhaps even most) circumstance. If this were not true, it would never have made it out of the lab. So, in a way, "It works for me" posts don't really say anything.

2) There have been at least 2 situations in my experience where ipv6 was screwing things up and the solution was to disable it. Since the number of times that I've said "Hey! Wow! This is really cool and ipv6 allowed me to do something I couldn't otherwise do." is zero (Yes, zero!), I cannot conclude anything other than that ipv6 is a bad thing and is TBA.
If this post appears in the wrong forums category, my apologies.

Heater
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Re: Disabling IPV6, yep that old Chestnut again..

Sun Jan 01, 2017 3:22 pm

Martin Frezman,
Short answer: If it causes a problem, it is a problem.
OK. But that does not tell us anything. It's not very helpful. I'd rather find out the root cause of the problem if possible. I'd rather remove that nail from my foot than cut my leg off to cure the pain, as it were.

You are right my "It works for me" post is not helpful either. It is however background as to why I'm asking why it works for me without issue and why others have problems.

It's not clear to me why IPv6, or anything else for that matter, is a bad idea just because you see no use for it.

I went back and reread your earlier post. It does not tell us anything about the root of the problem.

It does state that supporting the idea of IPv6 is a "religion". That for some unspecified reason IPv6 is a bad thing. And some how it's likened to systemd. Needless to say I disagree with all of that.

Now I have to make another useless "I works for me" statement. I have installed Debian dozens of times. On PC's,raspies, assorted other machines. Never have I had to disable IPv6 anywhere to do so. So now I'm wondering what the potential problem there is as well.

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Re: Disabling IPV6, yep that old Chestnut again..

Sun Jan 01, 2017 3:38 pm

It's hardly new tech, it just a shame that so many ISPs won't adopt it.
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