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WvR
Apprentice
Joined: 03 Mar 2011
Posts: 200
Location: Tsuruga, Japan
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 Posted: Mon Feb 26, 2018 2:07 am Post subject: Possibility to create a kernel without IPv6? |
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Environment: university computer network with high capacity internet connection.
Since more than a year, I have noticed a problem with internet connections at work, which seems to only affect linux PCs. The symptoms are simple: it takes a long time to set up a connection to a website; once the website has been contacted the data is downloaded quickly. WIth Windows machines there is absolutely no problem.
Downloading software packages for Gentoo updates is also excruciatingly slow. Here I noticed the following pattern:
- the download server is accessed with an IPv6 address, which always times out
- then the next server is tried with IPv6 and times out
- repeat until servers exhausted
When I set GENTOO_MIRRORS, the process is as follows:
- the GENTOO_MIRROR is accessed with IPv6, which times out
- when the IPv6 times out, portage tries again with IPv4 address, which works immediately
I have a feeling that something is going with our network servers (the university is behind a big firewall, with very few open ports). Perhaps the university servers somehow do not like IPv6.
Thus, I thought it might be worthwhile to test whether things are better if I disable IPv6 in Gentoo. But..... is that possible? Or is there an easy way (perhaps in a configuration file) to tell network applications to prefer IPv4 over IPv6? |
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Ant P.
Watchman
Joined: 18 Apr 2009
Posts: 6920
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| Posted: Mon Feb 26, 2018 5:12 am Post subject: |
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Add this to make.conf to disable IPv6 in portage (the manpage doesn't say when the backslashes are required, so try removing those if it doesn't work):
| Code: | | FETCHCOMMAND='wget --inet4-only -t 3 -T 60 --passive-ftp -O "\${DISTDIR}/\${FILE}" "\${URI}"' |
Or just add inet4-only to /etc/wgetrc to make it global. Browsers shouldn't need extra configuration. |
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mike155
Advocate
Joined: 17 Sep 2010
Posts: 4438
Location: Frankfurt, Germany
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| Posted: Mon Feb 26, 2018 8:50 am Post subject: |
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| If you don't need IPv6 at all, you could boot Linux with kernel option 'ipv6.disable=1'. |
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krinn
Watchman
Joined: 02 May 2003
Posts: 7470
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| Posted: Mon Feb 26, 2018 1:45 pm Post subject: |
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like mike155 said but also two other choices:
temp disable it but you have boot with ipv6 kernel and ipv6 up
| Code: | | echo 1 > /proc/sys/net/ipv6/conf/eth0/disable_ipv6 |
or build a kernel without ipv6 support
| Code: | | # CONFIG_IPV6 is not set |
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WvR
Apprentice
Joined: 03 Mar 2011
Posts: 200
Location: Tsuruga, Japan
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| Posted: Tue Feb 27, 2018 2:26 am Post subject: |
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| Ant P. wrote: | Add this to make.conf to disable IPv6 in portage (the manpage doesn't say when the backslashes are required, so try removing those if it doesn't work):
| Code: | | FETCHCOMMAND='wget --inet4-only -t 3 -T 60 --passive-ftp -O "\${DISTDIR}/\${FILE}" "\${URI}"' |
Or just add inet4-only to /etc/wgetrc to make it global. Browsers shouldn't need extra configuration. |
I set
prefer-family = IPv4
in /etc/wgetrc and that really improves performance on emerge-webrsync etc. So that is already a good start! I will also try the other suggestions to prefer IPv4 for other network applications. |
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WvR
Apprentice
Joined: 03 Mar 2011
Posts: 200
Location: Tsuruga, Japan
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| Posted: Tue Feb 27, 2018 2:28 am Post subject: |
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| krinn wrote: | like mike155 said but also two other choices:
temp disable it but you have boot with ipv6 kernel and ipv6 up
| Code: | | echo 1 > /proc/sys/net/ipv6/conf/eth0/disable_ipv6 |
or build a kernel without ipv6 support
| Code: | | # CONFIG_IPV6 is not set |
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In menuconfig:
Networking Support -> Networking options -> The IPv6 Protocol -> should I simply de-select everything here? |
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mike155
Advocate
Joined: 17 Sep 2010
Posts: 4438
Location: Frankfurt, Germany
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| Posted: Tue Feb 27, 2018 8:44 am Post subject: |
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| Quote: | | should I simply de-select everything here? |
If you want to go that way: don't de-select options inside of 'Networking Support -> Networking options -> The IPv6 Protocol'. De-select 'Networking Support -> Networking options -> The IPv6 Protocol' itself. |
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WvR
Apprentice
Joined: 03 Mar 2011
Posts: 200
Location: Tsuruga, Japan
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| Posted: Wed Feb 28, 2018 4:32 am Post subject: |
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| mike155 wrote: | | If you want to go that way: don't de-select options inside of 'Networking Support -> Networking options -> The IPv6 Protocol'. De-select 'Networking Support -> Networking options -> The IPv6 Protocol' itself. |
But it seems that it is not possible to de-select "The IPv6 Protocol" in its entirety.
For now, I have used the trick to disable to IPv6 protocol via /sys/proc/... and that is already greatly improving the situation. For now, I think I will just wait and see where we go from here. |
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Chiitoo
Administrator
Joined: 28 Feb 2010
Posts: 2569
Location: Here and Away Again
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| Posted: Wed Feb 28, 2018 10:56 am Post subject: ><)))°€ |
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| WvR wrote: | | But it seems that it is not possible to de-select "The IPv6 Protocol" in its entirety. |
It appears to be forcefully enabled in cases where
| Code: | | GENTOO_LINUX_INIT_SYSTEMD [=y] && GENTOO_LINUX [=y] && GENTOO_LINUX_UDEV [=y] |
is true.
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Kindest of regardses. |
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gengreen
Apprentice
Joined: 23 Dec 2017
Posts: 150
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| Posted: Thu Mar 08, 2018 12:06 am Post subject: |
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| Unrelated to the main question but as I also remove the ipv6 support from whenever I can, add the useflag -ipv6 to your make.conf can be useful. |
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turtles
Veteran
Joined: 31 Dec 2004
Posts: 1654
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| Posted: Mon Mar 12, 2018 7:20 pm Post subject: |
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I would guess in 2018 most Gentoo users are on a network that does not use IPV6 at all.
I have no problem with the idea of IPV6 it sounds great.
But somehow on Gentoo systems DNS first queries IPV6 waits for a timeout then uses IPV4, this slows my internet down to a crawl.
DNS on Gnu/Linux seems to prefer IPV6, and in my experience Linux software gets buggy with IPV6 not compiled in.
I would try this first:
| mike155 wrote: | | If you don't need IPv6 at all, you could boot Linux with kernel option 'ipv6.disable=1'. |
That works well for me, no need to have use flags or kernel compiled without IPV6.
No special settings to remember etc..
On other nix systems I was able to fix this DNS preference for IPV6 in
By adding something like:
| Code: |
scopev4 ::ffff:169.254.0.0/112 2
scopev4 ::ffff:127.0.0.0/104 2
scopev4 ::ffff:0.0.0.0/96 14
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And there may be a way to disable IPV6 for DNS completely in that file?
Someone might chime in here with that.
Cheers
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