<p>I want all members of security group <code>sg-a</code> to be able to access several ports, e.g. 6443 (kubernetes api server), on all instances in <code>sg-a</code>: including themselves. </p>

<p>I create a rule in <code>sg-a</code> that says</p>

<ul>
<li>Type: Custom TCP</li>
<li>Protocol: TCP</li>
<li>Port Range: 6443</li>
<li>Source: <code>sg-a</code> </li>
</ul>

<p>However, <code>instanceA</code> cannot access port 6443 on itself. </p>

<p>When I update "Source" to Source: <code>instanceA.public.ip.address</code> , then <code>instanceA</code> can access port 6443 on itself.</p>

<p>However, I now have instance specific rules in my security group. If possible, I would like to find a solution where I do not have to add new rules when I add a new instance to my security group</p>

MCI
<p>For the security group to operate as you describe, the instances will need to connect to each other via a <strong>Private IP address</strong>.</p>

<p>The fact that it works if you allow the Public IP address indicates that the connection is being made by the public IP address.</p>
