After turning off Router Advertisements from a cisco device on the network, I get the expected Network is unreachable message when the MTA tries IPv6 and right after that the message goes through using v4.<div><br>Thank you for your assistance.</div>
<div><br></div><div><div>Jun 21 03:41:48 onion postfix/qmgr[1348]: 3CCDA1A1123: from=<<a href="mailto:root@example.com">root@example.com</a>>, size=452, nrcpt=1 (queue active)</div><div>Jun 21 03:41:48 onion postfix/smtp[22635]: <span style="background-color:rgb(255,255,51)">connect to <a href="http://gmail-smtp-in-v4v6.l.google.com">gmail-smtp-in-v4v6.l.google.com</a>[2001:4860:b007::1a]:25: Network is unreachable</span></div>
<div>Jun 21 03:41:50 onion postfix/smtp[22635]: 3CCDA1A1123: to=<<a href="mailto:myaddress@gmail.com">myaddress@gmail.com</a>>, relay=<a href="http://gmail-smtp-in-v4v6.l.google.com">gmail-smtp-in-v4v6.l.google.com</a>[209.85.225.26]:25, delay=1.9, delays=0.21/0.02/0.86/0.84, dsn=2.0.0, status=sent (250 2.0.0 OK 1340264510 ab7si1761286igc.10)</div>
<div>Jun 21 03:41:50 onion postfix/qmgr[1348]: 3CCDA1A1123: removed</div><div><br></div><br><div class="gmail_quote">On Thu, Jun 21, 2012 at 3:32 AM, Bernhard Schmidt <span dir="ltr"><<a href="mailto:berni@birkenwald.de" target="_blank">berni@birkenwald.de</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Am <a href="tel:21.06.2012%2009" value="+12106201209">21.06.2012 09</a>:28, schrieb Mansoor Nathani:<br>
<br>
Hi,<br>
<div class="im"><br>
> I noticed it seems to be picking up some ip / address info from an IPv6<br>
> tunnel to Hurricane Electric.<br>
><br>
> I never configured this host with any such IPv6 information however.<br>
> The tunnel is using 2001:470:b148::/48 .<br>
<br>
</div>Well, someone in your network obviously did.<br>
<div class="im"><br>
> 2001:470:b148::/48 dev eth0 proto kernel metric 256 expires 0sec mtu<br>
</div><div class="im">> default via fe80::205:32ff:fee8:8b61 dev eth0 proto kernel metric 1024<br>
> expires 0sec mtu 1500 advmss 1440 hoplimit 64<br>
<br>
</div>The device with the MAC address 00:05:32:e8:8b:61 is sending router<br>
advertisements with the prefix 2001:470:b148::/48 . Lucky (or unlucky)<br>
for you they are wrongly advertising a /48, not a /64, so SLAAC does not<br>
work and you don't get an address assigned. I'm a bit confused at the<br>
moment, since I thought Linux was handling "has defaultroute but not a<br>
global address" correctly these days, but obviously there are still some<br>
issues.<br>
<br>
Hunt down that bogus advertisement, that should solve the problem.<br>
<span class="HOEnZb"><font color="#888888"><br>
Bernhard<br>
</font></span></blockquote></div><br></div>