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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New"">I think this is a combination of two things...<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo2"><![if !supportLists]><span style="font-size:12.0pt;font-family:"Courier New""><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:12.0pt;font-family:"Courier New"">When a VM initiates outbound communications, the egress rules<o:p></o:p></span></p>
<p class="MsoListParagraph"><span style="font-size:12.0pt;font-family:"Courier New"">allow associated return traffic. So if you allow outbound echo<o:p></o:p></span></p>
<p class="MsoListParagraph"><span style="font-size:12.0pt;font-family:"Courier New"">request, the return echo reply will also be allowed.<o:p></o:p></span></p>
<p class="MsoListParagraph"><span style="font-size:12.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo2"><![if !supportLists]><span style="font-size:12.0pt;font-family:"Courier New""><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:12.0pt;font-family:"Courier New"">The router interface will respond to ping.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New"">- Jack<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Narasimhan, Vivekanandan
<br>
<b>Sent:</b> Tuesday, May 20, 2014 8:07 AM<br>
<b>To:</b> OpenStack Development Mailing List (not for usage questions)<br>
<b>Subject:</b> [openstack-dev] [Neutron][Security Groups] Pings to router ip from VM with default security groups<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi ,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We have been trying to understand behavior of security group rules in icehouse stable.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The default security group contains 4 rules, two ingress and two egress.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The two ingress rules are one for IPv4 and other for IPv6. <o:p>
</o:p></p>
<p class="MsoNormal">We see both the ingress rules use cyclic security groups, wherein the rule contains remote_security_group_id
<o:p></o:p></p>
<p class="MsoNormal">the same as the security_group_id itself.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Vm1 <-<span style="font-family:Wingdings">à</span> R1 <span style="font-family:Wingdings">
ß</span>> Vm2<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Vm1 20.0.0.2<o:p></o:p></p>
<p class="MsoNormal">R1 interface 1 – 20.0.0.1<o:p></o:p></p>
<p class="MsoNormal">R1 interface 2 – 30.0.0.1<o:p></o:p></p>
<p class="MsoNormal">Vm2 30.0.0.2<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We saw that with default security groups, Vm1 can ping its DHCP Server IP because of provider_rule in security group rules.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Vm1 is also able to ping Vm2 via router R1, as Vm1 port and Vm2 port share the same security group.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">However, we noticed that a Vm1 is also able to ping the router interfaces (R1 interface 1 ip - 20.0.0.1) and also ping router
<o:p></o:p></p>
<p class="MsoNormal">interface (R1 interface 2 IP – 30.0.0.1) successfully.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Router interfaces donot have security groups associated with them, so the router interface IPs won’ t get added to
<o:p></o:p></p>
<p class="MsoNormal">the IPTables of the CN where the Vm1 resides. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We are not able to figure how the ping from the Vm1 to the router interfaces work when
<o:p></o:p></p>
<p class="MsoNormal">no explicit rules are added to allow them.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Could you please throw some light on this?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">--<o:p></o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Vivek<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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