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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Perhaps this isn’t strictly HECnet related but as HECnet traffic is traversing some part of this weird arrangement via pydecnet, I’m taking a chance:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I run SIMH on Raspberry PIs under Raspbian Buster.<o:p></o:p></p>
<p class="MsoNormal">I have both IPv4 and IPv6 networking switched on and a router/DHCP(v6)/DNS infrastructure to cope successfully with it.<o:p></o:p></p>
<p class="MsoNormal">(Nothing is wireless for what I’m about to describe, not that it would make much difference)<o:p></o:p></p>
<p class="MsoNormal">SIMH’s simulated Ethernet devices on the PIs are TAP connections to a bridge device connection to a real eth0 – no problem here.<o:p></o:p></p>
<p class="MsoNormal">SIMH instances’ consoles and terminal MUX devices are listening on individual ports and I telnet into these usually from my PC via Putty.<o:p></o:p></p>
<p class="MsoNormal">The DNS servers do not have AAAA for the PIs, just A, so the PC connects to the PIs via IPv4 – no problem here.<o:p></o:p></p>
<p class="MsoNormal">The PIs show the SIMH instances listening on the right TCP ports but when I filter with -4, ie:<br>
netstat –a -4<o:p></o:p></p>
<p class="MsoNormal">I don’t see SIMH listening. When I filter with -6, ie:<o:p></o:p></p>
<p class="MsoNormal"> netstat –a -6<o:p></o:p></p>
<p class="MsoNormal">I do see a listen on those ports.<o:p></o:p></p>
<p class="MsoNormal">I notice that, for example, ssh listens on 0.0.0.0:ssh AND [::]:ssh but SIMH listens only on *:8601 (for example)<b><br>
</b>The * seems to show up only when I restrict the search to the ipv6 family.<o:p></o:p></p>
<p class="MsoNormal">The * seems to indicate a listen with no ‘family’ preference.<o:p></o:p></p>
<p class="MsoNormal">An established connection to *:8601 seems even stranger.<o:p></o:p></p>
<p class="MsoNormal">It only shows up when netstat is run with -6 but it shows the correct IPv4 addresses for each endpoint. It is an IPv4 connection anyway.<o:p></o:p></p>
<p class="MsoNormal">The ‘ss -6’ command shows up something even weirder for the established (IPv4) connections:<o:p></o:p></p>
<p class="MsoNormal">The local address port is: [::ffff:192.168.2.42]:8601 and the remote address port is: [::ffff:192.168.2.12]:61152<o:p></o:p></p>
<p class="MsoNormal">The IPv4 part of these ports is correct. Why are they ‘encapsulated’ in some IPv6 syntax and listed as IPv6 connections?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Can anybody point me in the right direction for some explanation please? My google keyword searching skills seem a little off today.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Regards,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Keith<o:p></o:p></p>
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