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Dear Helmut,<br>
<br>
Sorry for this letter. I want just to make some aspects of the
problem more clear.<br>
<br>
Joining all-router multicast group is a kernel option. Your host
send Router Solicitation requests (it's ICMPv6 code number 133) to
the all-routers multicast group. Sending of RS is controlling by the
kernel options through sysctl:<br>
<br>
$ sysctl -a | grep net.ipv6.conf.default.router_solicitations<br>
<br>
The default number of router solicitation messages to send is 3. You
can change it to 0 to disable RS if you want:<br>
<br>
# sysctl -w "grep net.ipv6.conf.default.router_solicitations=0"<br>
<br>
and write this option value to /etc/sysctl.conf if You want to
preserve the value after the system reboot. There are possibility to
manage sysctl via Avahi.<br>
<br>
<br>
There is some security reasons in support of disabling RS in the
kernels of Your workstations, esp. if You use unmanaged ethernet
switches or managed ones without multicast group management. Where
is the problem? It could be almost IPv6 disaster to enable ipv6
forwarding in more than one of Your local stations or servers,
especially if the router-enabled kernel is not on router machine (so
called "fake router"). If that scenario happens and some or all of
Your stations autoconfigure the fake router local-ling address as a
default IPv6 nexthop, they'll lost their IPv6 connectivity.<br>
<br>
I'll recommend You not to use statefull or stateless
auto-configuration unless You can manage the access to You multicast
groups in the local ethernet. DHCPv6 (as a statefull host
configuration) do not solve the problem with fake routers - it uses
RS do discover the router too.<br>
<br>
Best regards<br>
Vesselin <br>
<br>
<br>
On 09/06/2011 05:33 PM, Helmut Drodofsky wrote:
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<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size: 10pt;
font-family:
"Tahoma","sans-serif";">Von:</span></b><span
style="font-size: 10pt; font-family:
"Tahoma","sans-serif";">
<a class="moz-txt-link-abbreviated" href="mailto:centos-bounces@centos.org">centos-bounces@centos.org</a>
[<a class="moz-txt-link-freetext" href="mailto:centos-bounces@centos.org">mailto:centos-bounces@centos.org</a>] <b>Im Auftrag von </b>Helmut
Drodofsky<br>
<b>Gesendet:</b> Dienstag, 6. September 2011 16:03<br>
<b>An:</b> 'CentOS mailing list'<br>
<b>Betreff:</b> [CentOS] ICMPv6 messages of type RS<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hallo,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">as described by CISCO in <o:p></o:p></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_7-2/ipv6_autoconfig.html">http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_7-2/ipv6_autoconfig.html</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US">a router hast to send
ICMPv6 messages of type RS to the all-router multicast
group: ff02::1 and <span class="code">ff02::2 for stateless
autoconfiguration.<o:p></o:p></span></span></p>
<p class="MsoNormal"><span class="code"><span lang="EN-US"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span class="code"><span lang="EN-US">How
can I activate this sending in CentOS?<o:p></o:p></span></span></p>
<p class="MsoNormal"><span class="code"><span lang="EN-US"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span lang="EN-US">Best regards</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US">Helmut<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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