[gentoo-user] Why I can't I build systemd without ipv6?

[gentoo-user] Why I can't I build systemd without ipv6?

[Daniel Frey]

I switched ISPs a couple months back and have been struggling with 
networking issues (not LAN, just WAN.)

I have discovered that something is broken with my ISP's ipv6 support, 
every time I go to a website there's a 10-second delay. When syncing 
portage today I saw what the delay is: apparently it tries ipv6 twice, 
fails, then resorts to ipv4 which works fine.

Most of my systems now have ipv6 support removed, and viola! no more 
delays.

Except for the three systems I have that run systemd. I went in the 
kernel config to disable ipv6, and it won't let me - looking at the 
dependency list, it's systemd blocking this.

So *why* on earth is it a dependency when (from what I've been reading 
after discovering this) many ISPs don't seem to support it properly yet?

And is there a way to build systemd without ipv6? Or am I going to have 
to revert these three systems back to openrc?

Dan

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Jack]

On 2017.10.13 13:29, Daniel Frey wrote:
> I switched ISPs a couple months back and have been struggling with  
> networking issues (not LAN, just WAN.)
> 
> I have discovered that something is broken with my ISP's ipv6  
> support, every time I go to a website there's a 10-second delay. When  
> syncing portage today I saw what the delay is: apparently it tries  
> ipv6 twice, fails, then resorts to ipv4 which works fine.
> 
> Most of my systems now have ipv6 support removed, and viola! no more  
> delays.
> 
> Except for the three systems I have that run systemd. I went in the  
> kernel config to disable ipv6, and it won't let me - looking at the  
> dependency list, it's systemd blocking this.
> 
> So *why* on earth is it a dependency when (from what I've been  
> reading after discovering this) many ISPs don't seem to support it  
> properly yet?
> 
> And is there a way to build systemd without ipv6? Or am I going to  
> have to revert these three systems back to openrc?
> 
> Dan
Pretty much stabbing in the dark, but can you disable ipv6 somewhere in  
network configuration?   Can you compile it into the kernel as a  
module, and then blacklist it so it doesn't get loaded?

Jack

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[daniel]

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[gentoo-user] Re: Why I can't I build systemd without ipv6?

[Grant Edwards]

On 2017-10-13, Daniel Frey <djqfrey@gmail.com> wrote:


> And is there a way to build systemd without ipv6? Or am I going to have 
> to revert these three systems back to openrc?
     ^^^^^^

You misspelled "upgrade".

;)

-- 
Grant Edwards               grant.b.edwards        Yow! I am NOT a nut....
                                  at               
                              gmail.com            

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Canek Peláez Valdés]

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On Fri, Oct 13, 2017 at 12:29 PM, Daniel Frey <djqfrey@gmail.com> wrote:
>
> I switched ISPs a couple months back and have been struggling with
networking issues (not LAN, just WAN.)
>
> I have discovered that something is broken with my ISP's ipv6 support,
every time I go to a website there's a 10-second delay. When syncing
portage today I saw what the delay is: apparently it tries ipv6 twice,
fails, then resorts to ipv4 which works fine.
>
> Most of my systems now have ipv6 support removed, and viola! no more
delays.
>
> Except for the three systems I have that run systemd. I went in the
kernel config to disable ipv6, and it won't let me - looking at the
dependency list, it's systemd blocking this.
>
> So *why* on earth is it a dependency when (from what I've been reading
after discovering this) many ISPs don't seem to support it properly yet?
>
> And is there a way to build systemd without ipv6? Or am I going to have
to revert these three systems back to openrc?

Have you tried to boot the systems with  the "disable_ipv6=1" kernel
parameter?

Regards.
--
Dr. Canek Peláez Valdés
Profesor de Carrera Asociado C
Departamento de Matemáticas
Facultad de Ciencias
Universidad Nacional Autónoma de México

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Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Mike Gilbert]

On Fri, Oct 13, 2017 at 1:29 PM, Daniel Frey <djqfrey@gmail.com> wrote:
> I switched ISPs a couple months back and have been struggling with
> networking issues (not LAN, just WAN.)
>
> I have discovered that something is broken with my ISP's ipv6 support, every
> time I go to a website there's a 10-second delay. When syncing portage today
> I saw what the delay is: apparently it tries ipv6 twice, fails, then resorts
> to ipv4 which works fine.
>
> Most of my systems now have ipv6 support removed, and viola! no more delays.
>
> Except for the three systems I have that run systemd. I went in the kernel
> config to disable ipv6, and it won't let me - looking at the dependency
> list, it's systemd blocking this.
>
> So *why* on earth is it a dependency when (from what I've been reading after
> discovering this) many ISPs don't seem to support it properly yet?
>
> And is there a way to build systemd without ipv6? Or am I going to have to
> revert these three systems back to openrc?

Instead of stripping IPv6 out of your kernel, I would suggest that you
simply disable it on any network interfaces. How you do this would
depend on the method you use to manager your network config.

If you really want to remove IPv6 from your kernel, simply disable the
GENTOO_LINUX_INIT_SYSTEMD config option, and enable the other other
dependencies manually.

https://gitweb.gentoo.org/proj/linux-patches.git/tree/4567_distro-Gentoo-Kconfig.patch#n106

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Rich Freeman]

On Fri, Oct 13, 2017 at 11:34 AM, Mike Gilbert <floppym@gentoo.org> wrote:
> On Fri, Oct 13, 2017 at 1:29 PM, Daniel Frey <djqfrey@gmail.com> wrote:
>>
>> So *why* on earth is it a dependency when (from what I've been reading after
>> discovering this) many ISPs don't seem to support it properly yet?
>>
>> And is there a way to build systemd without ipv6? Or am I going to have to
>> revert these three systems back to openrc?
>
> Instead of stripping IPv6 out of your kernel, I would suggest that you
> simply disable it on any network interfaces. How you do this would
> depend on the method you use to manager your network config.
>
> If you really want to remove IPv6 from your kernel, simply disable the
> GENTOO_LINUX_INIT_SYSTEMD config option, and enable the other other
> dependencies manually.
>
> https://gitweb.gentoo.org/proj/linux-patches.git/tree/4567_distro-Gentoo-Kconfig.patch#n106
>

Just to expand a bit on this - the Gentoo-added service manager kernel
options are purely for convenience.  If you don't use gentoo-sources
you won't see them at all, because they're not part of the upstream
kernel.  All they do is pull in a bunch of other options.  Back in the
"good old days" people would look at the wiki (or pre-wiki) page for
openrc, see a list of mandatory kernel options, and set those options
when building their kernel.  Then somebody had the clever idea that it
would be easier for users to not shoot themselves in the foot if we
just gave a one-click option that set all the requirements
automatically.  However, the kernel configuration settings doesn't
really have any concept of "optional dependencies" - so we're stuck
with either not pulling in ipv6, which mostly works, or pulling it in,
which always works.

It is completely safe to answer no to whether you use systemd and
openrc, and then just manually answer yes to the things that you need.
Just keep in mind that you may run into issues if you don't enable
something that is truly mandatory, or you might have diminished
functionality.  It also means that you need to keep your ears open for
when the requirements change, since there won't be a Gentoo automagic
kernel config setting to change things for you.  That said, running an
upstream kernel isn't really that big a deal - I do that since I run
btrfs and zfs and want to have a bit more control over which series
I'm running to mitigate the bugs.

-- 
Rich

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Daniel Frey]

On 10/13/2017 10:41 AM, Jack wrote:
> Pretty much stabbing in the dark, but can you disable ipv6 somewhere in 
> network configuration?   Can you compile it into the kernel as a module, 
> and then blacklist it so it doesn't get loaded?
> 
> Jack

That's a good idea, I didn't think of that. Now that I've calmed down a 
bit... I went in the kernel config and it won't let me set it as a 
module, it's built-in only. I stepped back a bit to see if earlier in 
the tree I could switch it to a module but it doesn't appear to be an 
option.

Dan

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Daniel Frey]

On 10/13/2017 10:41 AM, daniel@sonck.nl wrote:
> IPv6 compiled into systemd is most likely for systemd-networkd. If 
> you're not using that part it shouldn't be a problem. If you're using 
> systemd-networkd, you can configure it to not do IPv6.
> 
> But, I would recommend configuring your system to not use IPv6 instead 
> of removing support. That should prevent most programs from trying IPv6.
> 

I also had a similar problem with my previous ISP, and found even if I 
configured it to not use ipv6, it didn't work, which is why I set 
USE="-ipv6" and removed support from the kernel completely.

Someone else suggested building it as a module and blacklisting the 
module, but for some reason I can't set ipv6 to be a module, it won't 
let me toggle it.

Dan

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Daniel Frey]

On 10/13/2017 11:34 AM, Mike Gilbert wrote:
> On Fri, Oct 13, 2017 at 1:29 PM, Daniel Frey <djqfrey@gmail.com> wrote:
>> I switched ISPs a couple months back and have been struggling with
>> networking issues (not LAN, just WAN.)
>>
>> I have discovered that something is broken with my ISP's ipv6 support, every
>> time I go to a website there's a 10-second delay. When syncing portage today
>> I saw what the delay is: apparently it tries ipv6 twice, fails, then resorts
>> to ipv4 which works fine.
>>
>> Most of my systems now have ipv6 support removed, and viola! no more delays.
>>
>> Except for the three systems I have that run systemd. I went in the kernel
>> config to disable ipv6, and it won't let me - looking at the dependency
>> list, it's systemd blocking this.
>>
>> So *why* on earth is it a dependency when (from what I've been reading after
>> discovering this) many ISPs don't seem to support it properly yet?
>>
>> And is there a way to build systemd without ipv6? Or am I going to have to
>> revert these three systems back to openrc?
> 
> Instead of stripping IPv6 out of your kernel, I would suggest that you
> simply disable it on any network interfaces. How you do this would
> depend on the method you use to manager your network config.

I have tried this, I set a static ipv4 IP on one machine and set it to 
not configure ipv6 at all. I still have a delay on this machine, but now 
it's not obvious what they delay is.

> 
> If you really want to remove IPv6 from your kernel, simply disable the
> GENTOO_LINUX_INIT_SYSTEMD config option, and enable the other other
> dependencies manually.
> 
> https://gitweb.gentoo.org/proj/linux-patches.git/tree/4567_distro-Gentoo-Kconfig.patch#n106
> 

I am going to try what Canek suggested and disable it on the kernel 
command line, but as the machine are currently updating I'll wait until 
they're done, then I'll try it. If it doesn't work then I'll set it up 
manually.

Dan

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Daniel Frey]

On 10/13/2017 11:05 AM, Canek Peláez Valdés wrote:
> 
> Have you tried to boot the systems with  the "disable_ipv6=1" kernel 
> parameter?
> 

I haven't, thanks for the tip. I'll wait until the machine finish 
updating and try that before messing around with the kernel config.

Dan

Re: [gentoo-user] Re: Why I can't I build systemd without ipv6?

[Daniel Frey]

On 10/13/2017 10:50 AM, Grant Edwards wrote:
> On 2017-10-13, Daniel Frey <djqfrey@gmail.com> wrote:
> 
> 
>> And is there a way to build systemd without ipv6? Or am I going to have
>> to revert these three systems back to openrc?
>       ^^^^^^
> 
> You misspelled "upgrade".
> 
> ;)
> 

That depends. One one of the three machines, I reported a bug about 
mdmon terminating too early in the shutdown process causing mdadm to 
mark my IMSM raid as dirty.

I had a workaround posted, but some time back it stopped working, so I 
tried systemd and haven't had that problem since. I really don't want to 
mess around with that again, having a resync'ing RAID on every reboot is 
tiresome and it thrashes the disks for no good reason. Not to mention it 
makes the system so slow for a few hours you can't even use it.

The other two I could switch, I think, without to much issues if it came 
down to it.

Dan

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Daniel Frey]

On 10/13/2017 12:02 PM, Rich Freeman wrote:
> Just to expand a bit on this - the Gentoo-added service manager kernel
> options are purely for convenience.  If you don't use gentoo-sources
> you won't see them at all, because they're not part of the upstream
> kernel.  All they do is pull in a bunch of other options.  Back in the
> "good old days" people would look at the wiki (or pre-wiki) page for
> openrc, see a list of mandatory kernel options, and set those options
> when building their kernel.  Then somebody had the clever idea that it
> would be easier for users to not shoot themselves in the foot if we
> just gave a one-click option that set all the requirements
> automatically.  However, the kernel configuration settings doesn't
> really have any concept of "optional dependencies" - so we're stuck
> with either not pulling in ipv6, which mostly works, or pulling it in,
> which always works.
> 
> It is completely safe to answer no to whether you use systemd and
> openrc, and then just manually answer yes to the things that you need.
> Just keep in mind that you may run into issues if you don't enable
> something that is truly mandatory, or you might have diminished
> functionality.  It also means that you need to keep your ears open for
> when the requirements change, since there won't be a Gentoo automagic
> kernel config setting to change things for you.  That said, running an
> upstream kernel isn't really that big a deal - I do that since I run
> btrfs and zfs and want to have a bit more control over which series
> I'm running to mitigate the bugs.
> 

That's good to know. I've been running gentoo-sources since 2003 or so. 
This is the only time I've noticed a problem, and thanks to the link 
that Mike posted if all else fails I'll turn off the automagic and 
configure things manually.

My networks are (were?) taken care of by networkmanager, but now that 
systemd is gone on more machines there's really no reason to keep it around.

Dan

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Vadim A. Misbakh-Soloviov]

Well, actually, you was alread adviced about some working methods of solving 
your issue (both right and wrong ones, but it is anyway your decision to take 
ones to use), so I'll just clarify the simple thing:

You can suffer on such problems in relation to IPv6 **ONLY** in the case when 
your ISP **DO** have IPv6 support (say, announce IPv6 preffix to you via SLAAC 
or DHCPv6), but having **BROKEN** IPv6 routing.

(well, it can also be the case that they had no VLAN per customer and you're 
getting foreign SLAAC/DHCPv6 announces from some of your neighbours, but I'd 
prefer to not think such a worse things about ISP I don't know yet :D)

So, ideally, you **SHOULD NOT** disable IPv6 on your side, but shame your ISP 
support line (for either broken IPv6 routing or not having VLAN per customer, 
depends on the real case) instead.



P.S. don't consider "capsed" words as crying, please. Just consider it as 
"extra bold" mark.

[gentoo-user] Re: Why I can't I build systemd without ipv6?

[Grant Edwards]

On 2017-10-13, Vadim A. Misbakh-Soloviov <gentoo@mva.name> wrote:

> Well, actually, you was alread adviced about some working methods of
> solving your issue (both right and wrong ones, but it is anyway your
> decision to take ones to use), so I'll just clarify the simple
> thing:
>
> You can suffer on such problems in relation to IPv6 **ONLY** in the
> case when your ISP **DO** have IPv6 support (say, announce IPv6
> preffix to you via SLAAC or DHCPv6), but having **BROKEN** IPv6
> routing.

It might not be the ISP that's broken.  It might be the user's
firewall/router.  A lot of the cheap consumer models are starting to
"support" IPv6 by default when it appears to them that the ISP
supports IPv6. But, the default IPv6 firewall/router settings aren't
always usable.

-- 
Grant Edwards               grant.b.edwards        Yow! I'm sitting on my
                                  at               SPEED QUEEN ... To me,
                              gmail.com            it's ENJOYABLE ... I'm WARM
                                                   ... I'm VIBRATORY ...

Re: [gentoo-user] Re: Why I can't I build systemd without ipv6?

[Daniel Frey]

On 10/13/2017 02:48 PM, Grant Edwards wrote:
> On 2017-10-13, Vadim A. Misbakh-Soloviov <gentoo@mva.name> wrote:
> 
>> Well, actually, you was alread adviced about some working methods of
>> solving your issue (both right and wrong ones, but it is anyway your
>> decision to take ones to use), so I'll just clarify the simple
>> thing:
>>
>> You can suffer on such problems in relation to IPv6 **ONLY** in the
>> case when your ISP **DO** have IPv6 support (say, announce IPv6
>> preffix to you via SLAAC or DHCPv6), but having **BROKEN** IPv6
>> routing.
> 
> It might not be the ISP that's broken.  It might be the user's
> firewall/router.  A lot of the cheap consumer models are starting to
> "support" IPv6 by default when it appears to them that the ISP
> supports IPv6. But, the default IPv6 firewall/router settings aren't
> always usable.
> 

I'm currently using the ISP provided router, as I don't have anything 
ATM that can handle 150 mbps symmetrical.

Dan

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Daniel Frey]

On 10/13/2017 11:05 AM, Canek Peláez Valdés wrote:
> 
> Have you tried to boot the systems with  the "disable_ipv6=1" kernel 
> parameter?
> 

I just tried this, and it doesn't seem to help.

# cat /proc/cmdline
disable_ipv6=1 root=/dev/md126p3 rd.auto=1 quiet rootfstype=ext4 
init=/usr/lib/systemd/systemd

But:

# dmesg | grep -i ipv6
[   22.218113] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[   22.241260] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[   26.421072] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready


I'll have to try a different solution later on. First I need to figure 
out why my nfs mounts aren't mounting on that PC, but that belongs in a 
different thread. I don't want to break things any more until that's fixed.

Dan

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Tom H]

On Fri, Oct 13, 2017 at 5:58 PM, Daniel Frey <djqfrey@gmail.com> wrote:
> On 10/13/2017 11:05 AM, Canek Peláez Valdés wrote:
>>
>> Have you tried to boot the systems with  the "disable_ipv6=1" kernel
>> parameter?
>
> I just tried this, and it doesn't seem to help.
>
> # cat /proc/cmdline
> disable_ipv6=1 root=/dev/md126p3 rd.auto=1 quiet rootfstype=ext4
> init=/usr/lib/systemd/systemd
>
> But:
>
> # dmesg | grep -i ipv6
> [   22.218113] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
> [   22.241260] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
> [   26.421072] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready

it's "ipv6.disable_ipv6=1" not "disable_ipv6=1".

Re: [gentoo-user] Re: Why I can't I build systemd without ipv6?

[Mick]

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On Friday, 13 October 2017 22:55:50 BST Daniel Frey wrote:
> On 10/13/2017 02:48 PM, Grant Edwards wrote:
> > On 2017-10-13, Vadim A. Misbakh-Soloviov <gentoo@mva.name> wrote:
> >> Well, actually, you was alread adviced about some working methods of
> >> solving your issue (both right and wrong ones, but it is anyway your
> >> decision to take ones to use), so I'll just clarify the simple
> >> thing:
> >> 
> >> You can suffer on such problems in relation to IPv6 **ONLY** in the
> >> case when your ISP **DO** have IPv6 support (say, announce IPv6
> >> preffix to you via SLAAC or DHCPv6), but having **BROKEN** IPv6
> >> routing.
> > 
> > It might not be the ISP that's broken.  It might be the user's
> > firewall/router.  A lot of the cheap consumer models are starting to
> > "support" IPv6 by default when it appears to them that the ISP
> > supports IPv6. But, the default IPv6 firewall/router settings aren't
> > always usable.
> 
> I'm currently using the ISP provided router, as I don't have anything
> ATM that can handle 150 mbps symmetrical.
> 
> Dan

I'm guessing the delay is due to DNS resolution missing of being misconfigured 
somewhere in your/your ISPs network.  Could you tweak your router's DNS 
resolver addresses to point to OpenDNS resolvers, or some such if your ISP's 
are not working properly?

-- 
Regards,
Mick

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Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Daniel Frey]

On 10/14/2017 12:37 AM, Tom H wrote:
> On Fri, Oct 13, 2017 at 5:58 PM, Daniel Frey <djqfrey@gmail.com> wrote:
>> On 10/13/2017 11:05 AM, Canek Peláez Valdés wrote:
>>>
>>> Have you tried to boot the systems with  the "disable_ipv6=1" kernel
>>> parameter?
>>
>> I just tried this, and it doesn't seem to help.
>>
>> # cat /proc/cmdline
>> disable_ipv6=1 root=/dev/md126p3 rd.auto=1 quiet rootfstype=ext4
>> init=/usr/lib/systemd/systemd
>>
>> But:
>>
>> # dmesg | grep -i ipv6
>> [   22.218113] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
>> [   22.241260] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
>> [   26.421072] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
> 
> it's "ipv6.disable_ipv6=1" not "disable_ipv6=1".
> 

Argh, I shouldn't have assumed that it was the full parameter. Oh well, 
on that machine, I managed to switch back to openrc. That didn't go real 
smoothly, portage couldn't figure out how to do it on it's own after 
switching profiles, it was blindly removing and rebuilding some packages 
manually that eventually made it work and not want to pull in systemd again.

After that, I was able to reconfigure the kernel without ipv6 at all... 
rebooted... and openrc Just Worked(tm) with my network issue gone.

For the other two, I'll try again but this time with the proper kernel 
parameter. That could've saved me a lot of time, but oh well.

Dan

Re: [gentoo-user] Re: Why I can't I build systemd without ipv6?

[Daniel Frey]

On 10/14/2017 04:05 AM, Mick wrote:
> On Friday, 13 October 2017 22:55:50 BST Daniel Frey wrote:
>> On 10/13/2017 02:48 PM, Grant Edwards wrote:
>>> On 2017-10-13, Vadim A. Misbakh-Soloviov <gentoo@mva.name> wrote:
>>>> Well, actually, you was alread adviced about some working methods of
>>>> solving your issue (both right and wrong ones, but it is anyway your
>>>> decision to take ones to use), so I'll just clarify the simple
>>>> thing:
>>>>
>>>> You can suffer on such problems in relation to IPv6 **ONLY** in the
>>>> case when your ISP **DO** have IPv6 support (say, announce IPv6
>>>> preffix to you via SLAAC or DHCPv6), but having **BROKEN** IPv6
>>>> routing.
>>>
>>> It might not be the ISP that's broken.  It might be the user's
>>> firewall/router.  A lot of the cheap consumer models are starting to
>>> "support" IPv6 by default when it appears to them that the ISP
>>> supports IPv6. But, the default IPv6 firewall/router settings aren't
>>> always usable.
>>
>> I'm currently using the ISP provided router, as I don't have anything
>> ATM that can handle 150 mbps symmetrical.
>>
>> Dan
> 
> I'm guessing the delay is due to DNS resolution missing of being misconfigured
> somewhere in your/your ISPs network.  Could you tweak your router's DNS
> resolver addresses to point to OpenDNS resolvers, or some such if your ISP's
> are not working properly?
> 

No, the DNS was working. It was trying to connect to a specific ipv6 
address to sync, and failing (twice.)

That's what I initially thought too, but checked name resolution and it 
was returning proper addresses.

I even thought (before I started to remove systemd from my old laptop) I 
could save time by disabling ipv6 on the ISP router (my cell phone 
suffers the same delay), but then it wouldn't even connect to their network.

Dan

Re: [gentoo-user] Why I can't I build systemd without ipv6?

[Daniel Frey]

On 10/13/2017 01:58 PM, Vadim A. Misbakh-Soloviov wrote:
> So, ideally, you **SHOULD NOT** disable IPv6 on your side, but shame your ISP
> support line (for either broken IPv6 routing or not having VLAN per customer,
> depends on the real case) instead.
> 

I don't want to waste hours/days/weeks trying to get past tier 1 
support. I've tried this before (I've had this ISP over 10 years ago.)

Dan