[gentoo-user] IPv4 & IPv6

[gentoo-user] IPv4 & IPv6

[Hartmut Figge]

Greetings,

I do not know why my machine suddenly local uses IPv6 instead of IPv4. I
noticed it today when I was unable to retrieve mail. syslog now shows

xinetd[3763]: START: pop-3 from=::1
instead of the former
xinetd[3761]: START: pop-3 pid=22632 from=127.0.0.1

and 'telnet localhost pop3' fails unless I force IPv4 with
'telnet -4 localhost pop3'.

I was unable to find the place where I could change this behavior, so I
used a dirty trick.

----- /etc/hosts -----
# IPv4 and IPv6 localhost aliases
127.0.0.1 localhost
# ::1   localhost
---------------

Commenting out the last line helped and I could get my mails. But that
is really a dirty trick. *g*.

I have never used IPv6, I don't intend to and I have forgotten most of
what I may have known about the issue. Hopefully on of you knows the
right way.

Hartmut

Re: [gentoo-user] IPv4 & IPv6

[Klaus Ethgen]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

Hi,

Am Sa den 28. Apr 2018 um  7:09 schrieb Hartmut Figge:
> I do not know why my machine suddenly local uses IPv6 instead of IPv4. I
> noticed it today when I was unable to retrieve mail. syslog now shows
[...]
> ----- /etc/hosts -----
> # IPv4 and IPv6 localhost aliases
> 127.0.0.1 localhost
> # ::1   localhost
> ---------------
> 
> Commenting out the last line helped and I could get my mails. But that
> is really a dirty trick. *g*.

You might add the following line in /etc/gai.conf:
   precedence ::ffff:0:0/96  100

instead of
   precedence ::ffff:0:0/96  10

Note that you need the full precedence-block if it is commented out.
Just change that line.

Regards
   Klaus
- -- 
Klaus Ethgen                                       http://www.ethgen.ch/
pub  4096R/4E20AF1C 2011-05-16            Klaus Ethgen <Klaus@Ethgen.ch>
Fingerprint: 85D4 CA42 952C 949B 1753  62B3 79D0 B06F 4E20 AF1C
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[gentoo-user] Re: IPv4 & IPv6

[Hartmut Figge]

Klaus Ethgen:

>You might add the following line in /etc/gai.conf:
>   precedence ::ffff:0:0/96  100
>
>instead of
>   precedence ::ffff:0:0/96  10

Interesting. That works.

>Note that you need the full precedence-block if it is commented out.
>Just change that line.

All lines in  /etc/gai.conf were commented out. I doubt that I ever
heard of that file.

Thanks. Still curious why the behavior changed yesterday. But only a
little. :)

Hartmut

Re: [gentoo-user] IPv4 & IPv6

[Walter Dnes]

On Sat, Apr 28, 2018 at 08:09:35AM +0200, Hartmut Figge wrote

> I do not know why my machine suddenly local uses IPv6 instead of
> IPv4. I noticed it today when I was unable to retrieve mail. syslog
> now shows

  The "ipv6" USE flage is enabled by default.  If you do not currently
use or need IPV6, then add "-ipv6" to USE in make.conf, and run...

 emerge --changed-use --deep --update @world

...to get rid of ipv6 on your system.

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications