<html>
    <head>
      <base href="https://bugzilla.netfilter.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Stateless NAT ICMP Payload Mismatch"
   href="https://bugzilla.netfilter.org/show_bug.cgi?id=1771">1771</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Stateless NAT ICMP Payload Mismatch
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>nftables
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>x86_64
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>other
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P5
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>nft
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>pablo@netfilter.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>echo@lethedata.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>When using the following ruleset to stateless NAT, ICMP payloads are not
mangled. This leads to a mismatch between packet IPv4 Header and ICMP IPv4
Header Payload in destination-unreachable (type 3) packets causing dropped
packets by the receiving host.

Internal to external:
IPv4 Header - Src: 192.0.2.2, Dst: 100.64.1.105
ICMP Type 3 Payload - Src: 203.0.113.100, Dst: 192.0.2.2

External to internal:
   IPv4 Header - Src: 203.0.113.100, Dst: 203.0.113.200
   ICMP Type 3 Payload - Src: 203.0.113.200, Dst: 100.64.1.105

table ip NAT {
   chain prerouting {
      type filter hook prerouting priority raw; policy accept;
         iif "eth0" ip daddr 203.0.113.100 ip daddr set 100.64.1.105
notrack return
   }

   chain postrouting {
      type filter hook postrouting priority raw; policy accept;
         oif "eth0" ip saddr 100.64.1.105 ip saddr set 203.0.113.100
notrack return
   }
}

OS: Void Linux
version: nftables v1.1.0 (Commodore Bullmoose)</pre>
        </div>
      </p>


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