Ubuntu Linux - Suggestions needed

Bernhard Schmidt berni at birkenwald.de
Mon Apr 2 21:35:34 CEST 2007

Andrew Alston wrote:

> In ubuntu linux feisty release IPv6 will officially be disabled by default
> at this point.  That is unless a solution is found within the next 48 hours
> to stop the problem of what they claim as slow fallbacks on non-v6 enabled
> networks.

To add some more information:

is the bug-report causing this

The "fix" is to blacklist the ipv6 module so it won't get loaded 
automatically as soon as any program requests it. Furthermore ifupdown 
has been altered to modprobe ipv6 if it hits any IPv6 related 
configuration in /etc/network/interfaces

Unfortunately this is not the case for the supposed default end-user 
network with stateless autoconfiguration, so those boxes will end up not 
having IPv6.

I'm not exactly sure how this bug solves anything. Generally, there seem 
to be two kinds of problems

a) getaddrinfo() does AAAA/A lookups, but some el-cheapo SOHO routers 
break on !A lookups and send crap or even nothing over the wire

b) networks where it appears there is IPv6 (RA present), but no (global) 
address is assigned. This might be the case for ULA (although those 
should definitely return unreachable when the TCP SYN tries to cross the 
boundary) or, where I have hit it, RA is configured with no-autoconfig.

As far as I understood the bug report (and from my experience), the main 
problem is a) which is _NOT_ changed with this "bugfix". getaddrinfo() 
still queries both address families even if the IPv6 module is not loaded.


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