squid-deb-proxy problem on Raring, IPv6 I think.

[Karl Auer]

On Sun, 2013-02-24 at 18:14 -0500, Tom H wrote:
> > How exactly does the client determine the address of the proxy?
> With "avahi-browse".

Then the problem is that the client is not properly recognising and
using an IPv6 link local address. This should be reported to the authors
as a bug. Why? Because it is entirely appropriate, if the client and
proxy are on the same host or the same subnet, that they should
communicate via link local addresses.

> The problem is that the OP needs an ipv4 address to be returned not an
> ipv6 one.

I disagree. The address avahi returned was just fine, and would work -
if the client used it properly. It would work just as well as an IPv4
one, and indeed should be used if possible. What the OP wants is an
address that will actually work, right now, and the workaround for the
deficiency in the client is to make sure that avahi doesn't give it an
IPv6 link local address.

So your solution - disable IPv6 in avahi - is absolutely the right way
to go. Still ugly, but the minimum damage needed to be effective.

>  (If he wanted an ipv6 one, I don't think that he'd want a
> link-local ipv6 address to be returned because I don't think that it
> would work, unless ipv6 link-local addresses are different from ipv4
> ones in this respect.)

Well, we know empirically that they do not work in this particular case,
but that's different from just not working generally.

> The one that "deb-squid-proxy" uses returns one or the other
> - and according to the bug reports that I've seen, it returns the ipv6
> one more often.

It rather depends on HOW it is being returned. If it's integrated into
the local resolver somehow, then it should always return both and the
local resolver should order them appropriately, with the higher-layer
software using them in that order, without reference to address family.
If it is not returning both, or is returning both without reference to
the local resolver, then the higher-layer software has to be
specifically written to handle IPv6 (which is sad, because it shouldn't
have to).

> > And optionally make the equivalent change to /etc/sysctl.conf to make
> > the change permanent.
> Why optionally? :)

Because if it doesn't fix the problem you will want to turn it back on.

Regards, K.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer
http://www.biplane.com.au/blog

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