netdev - Re: bad interaction between privacy extensions, prefix lifetimes and protocols that maintain long-term connections.

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Message-ID: <20170109214142.GA6465@mhcomputing.net>
Date:   Mon, 9 Jan 2017 13:41:42 -0800
From:   Matthew Hall <mhall@...omputing.net>
To:     peter green <plugwash@...link.net>
Cc:     debian-ipv6@...ts.debian.org, netdev@...r.kernel.org
Subject: Re: bad interaction between privacy extensions, prefix lifetimes and
 protocols that maintain long-term connections.

On Sat, Jan 07, 2017 at 03:16:06PM +0000, peter green wrote:
> For the main MAC-based address the valid_lft is always short but it is 
> updated by new RAs so the address remains valid.
> 
> However privacy addresses inherit their valid_lft from the main MAC-based 
> address and unlike the main address it is not updated causing the addresses 
> to time out. I believe that the timeout of these privacy addresses is what 
> is causing my repeated disconnections from IRC.

Privacy addresses generally cause me nothing but absolute misery.

Despite the MAC address problem I usually end up disabling them just to be 
able to survive without losing my sanity due to issues like this one.

I have had all kinds of applications not work reliably because of them. 
Including Google Chrome / Chromium etc. IRC also seems like a likely victim, 
but I wouldn't have noticed because I use it from a system with a static 
address.

Perhaps a workaround would be using the MAC address override ability in the 
interfaces file pre-up script with "ip link set eth0 address 02:01:02:03:04:08".
Randomly generate one fake MAC per boot.

Matthew.