<div dir="ltr">Well, I can't tell for sure since I can't see your prefixes, but from this:<br><br> [ 725.945125] NAT64 Jool: Catching IPv6 packet: 64:ff9b::a21:1->64:ff9b::ac10:184<br><br>I can guess that maybe you jumped from the traditional SIIT tutorial straight to the NAT64 tutorial and didn't bother to change the addresses.<br><br>Your IPv6 nodes' network does not need to start with the translation prefix. That's a traditional SIIT-only thing. The point of Stateful NAT64 is that any IPv6 node can access the IPv4 side; not just a selected few where you have control over their addresses.<br><br>In traditional SIIT, you have three prefixes. One is the translation prefix, and the other ones are the network prefixes. The network prefixes are always subnetworks of the translation prefix. For example,<br><br> Translation prefix: 2001:db8::/64<br> IPv6 network prefix: 2001:db8::0102:0300/120<br> IPv4 network prefix (IPv6 implicit): <a href="http://1.2.4.0/24">1.2.4.0/24</a> (2001:db8::0102:0400/120)<br><br>So you send a packet from 2001:db8::0102:0301 to 2001:db8::0102:0401. This makes sense because these two addresses belong to different networks, and the translator simply needs to remove the translation prefix.<br><br>On the other hand, in Stateful NAT64, when you do this,<br><br> modprobe jool pool6=64:ff9b::/96<br><br>you have to think that you're essentially renaming the whole IPv4 Internet as 64:ff9b::/96. This being the case, Jool thinks that 64:ff9b::a21:1 is sending a packet to a node from its own network, and it somehow ended in the translator's hands. Which is technically legal in some situations (namely "hairpinning"), but this isn't one of them. As it is, Jool thinks that the IPv6 node is trying to attack it: <a href="https://tools.ietf.org/html/rfc6146#section-5.4">https://tools.ietf.org/html/rfc6146#section-5.4</a><br><br>I think that this should head you in the right direction. I can explain hairpinning and hairpinning loops if you want, but I don't think that you'll be needing it in the near future.<br><br>Alberto<br><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Apr 3, 2017 at 6:36 AM, Eduardo Montoya <span dir="ltr"><<a href="mailto:emontoya@kirale.com" target="_blank">emontoya@kirale.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi, is anyone able to explain me why this response packet is being dropped?<br><br><font size="1"><span style="font-family:monospace,monospace">[ 725.939726] NAT64 Jool: ==============================<wbr>=================<br>[ 725.939746] NAT64 Jool: Catching IPv4 packet: 172.16.1.132->172.16.1.141<br>[ 725.939757] NAT64 Jool: Step 1: Determining the Incoming Tuple<br>[ 725.939771] NAT64 Jool: Tuple: 172.16.1.132#43563 -> 172.16.1.141#20000 (UDP)<br>[ 725.939780] NAT64 Jool: Done step 1.<br>[ 725.939788] NAT64 Jool: Step 2: Filtering and Updating<br>[ 725.939816] NAT64 Jool: BIB entry: 64:ff9b::a21:1#49191 - 172.16.1.141#20000 (UDP)<br>[ 725.939835] NAT64 Jool: Session entry: 64:ff9b::a21:1#49191 - 64:ff9b::ac10:184#43563 | 172.16.1.141#20000 - 172.16.1.132#43563 (UDP)<br>[ 725.939845] NAT64 Jool: Done: Step 2.<br>[ 725.939854] NAT64 Jool: Step 3: Computing the Outgoing Tuple<br>[ 725.939869] NAT64 Jool: Tuple: 64:ff9b::ac10:184#43563 -> 64:ff9b::a21:1#49191 (UDP)<br>[ 725.939877] NAT64 Jool: Done step 3.<br>[ 725.939886] NAT64 Jool: Step 4: Translating the Packet<br>[ 725.939907] NAT64 Jool: Done step 4.<br>[ 725.939932] NAT64 Jool: Packet routed via device 'usb1'.<br>[ 725.939941] NAT64 Jool: Sending skb.<br>[ 725.940026] NAT64 Jool: Success.<br>[ 725.945090] NAT64 Jool: ==============================<wbr>=================<br>[ 725.945125] NAT64 Jool: Catching IPv6 packet: 64:ff9b::a21:1->64:ff9b::ac10:<wbr>184<br>[ 725.945142] NAT64 Jool: Step 1: Determining the Incoming Tuple<br>[ 725.945163] NAT64 Jool: Tuple: 64:ff9b::a21:1#49191 -> 64:ff9b::ac10:184#43563 (UDP)<br>[ 725.945174] NAT64 Jool: Done step 1.<br>[ 725.945185] NAT64 Jool: Step 2: Filtering and Updating<br>[ 725.945198] NAT64 Jool: Hairpinning loop. Dropping...<br>[ 726.139093] NAT64 Jool: ==============================<wbr>=================</span></font><br clear="all"><div><br></div><div>Thanks.<span class="HOEnZb"><font color="#888888"><br></font></span></div><span class="HOEnZb"><font color="#888888"><div><br>-- <br><div class="m_-2113417959869784967gmail_signature"><div dir="ltr"><span style="font-size:12.8px"> <b>Eduardo Montoya</b></span><b style="font-size:12.8px"> </b><div style="font-size:12.8px">------------------------------<wbr>--------------</div><div style="font-size:12.8px">Embedded Firmware Engineer</div><div style="font-size:12.8px">Kirale Technologies S.L.</div><div style="font-size:12.8px">Logroño, SPAIN</div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px"><a href="http://www.kirale.com/" style="color:rgb(17,85,204)" target="_blank">www.kirale.com</a></div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px"><img src="https://docs.google.com/uc?export=download&id=0Bx2AKWDAVrGtQ2RKbXZmTDFVbkU&revid=0Bx2AKWDAVrGtZzduemxSdEJMdmZuTHZHVVFaaUc5Y1pxc1FrPQ" height="33" width="96"></div></div></div>
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