<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta name="generator" content="pandoc" />
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes" />
<style>
html {
line-height: 1.2;
font-family: serif;
font-size: 0.9em;
color: black;
background-color: white;
}
body {
margin: 0;
margin-right: auto;
max-width: 36em;
padding: 1em;
hyphens: auto;
overflow-wrap: break-word;
text-rendering: optimizeLegibility;
font-kerning: normal;
}
@media print {
body {
background-color: transparent;
color: black;
font-size: 11pt;
}
p, h2, h3 {
orphans: 3;
widows: 3;
}
h2, h3, h4 {
page-break-after: avoid;
}
}
p {
margin: 1em 0;
}
a {
color: black;
}
a:visited {
color: black;
}
img {
max-width: 100%;
}
h1, h2, h3, h4, h5, h6 {
margin-top: 1.4em;
}
h5, h6 {
font-size: 1em;
font-style: italic;
}
h6 {
font-weight: normal;
}
ol, ul {
padding-left: 1.7em;
margin-top: 1em;
}
li > ol, li > ul {
margin-top: 0;
}
blockquote {
margin: 0.5em;
padding-left: 0.5em;
border-left: 2px solid #e6e6e6;
color: #444;
}
code {
font-family: 'Lucida Console', monospace;
font-size: 95%;
margin: 0;
}
pre {
margin: 1em 0;
overflow: auto;
}
pre code {
padding: 0;
overflow: visible;
overflow-wrap: normal;
}
.sourceCode {
background-color: transparent;
overflow: visible;
}
hr {
background-color: black;
border: none;
height: 1px;
margin: 1em 0;
}
table {
margin: 1em 0;
border-collapse: collapse;
width: 100%;
overflow-x: auto;
display: block;
font-variant-numeric: lining-nums tabular-nums;
}
table caption {
margin-bottom: 0.75em;
}
tbody {
margin-top: 0.5em;
border-top: 1px solid black;
border-bottom: 1px solid black;
}
th {
border-top: 1px solid black;
padding: 0.25em 0.5em 0.25em 0.5em;
}
td {
padding: 0.125em 0.5em 0.25em 0.5em;
}
header {
margin-bottom: 4em;
text-align: center;
}
code{white-space: pre-wrap;}
span.smallcaps{font-variant: small-caps;}
span.underline{text-decoration: underline;}
div.column{display: inline-block; vertical-align: top; width: 50%;}
div.hanging-indent{margin-left: 1.5em; text-indent: -1.5em;}
ul.task-list{list-style: none;}
q { quotes: "„" "”" "»" "«"; }
.display.math{display: block; text-align: center; margin: 0.5rem auto;}
</style>
</head>
<body>
<p>Hello!</p>
<p>On Wed, Jun 12, 2024 at 06:32:10PM +0700, Ville O wrote:</p>
<blockquote>
<p>At least some Huawei devices use a checksum of 0 for all IPv6 BFD UDP
packets after finishing Poll/Final. All packets sent with states other
than Up or with flags other than C have the correct checksums.</p>
<p>[…]</p>
<p>This issue could be worked around on the BIRD side at least on the
Linux platform. RFC6936 allows [3] for hosts to enable accepting IPv6
UDP with a checksum of 0 and this is implemented in Linux kernels from
3.16 with sockopt “UDP_NO_CHECK6_RX”. I have tested that this indeed
works: checksum 0 packets are received to AF_INET6, SOCK_DGRAM sockets
when it is enabled.</p>
<p>I wonder if it would be acceptable to enable this option on the IPv6
socket(s) used for BFD in BIRD, if supported by the platform?</p>
</blockquote>
<p>Patches welcome. It should be configurable and off by default. For
more information on how to contribute, see the contributing
guidelines:</p>
<pre><code>https://gitlab.nic.cz/labs/bird/-/blob/master/CONTRIBUTING.md</code></pre>
<p>Thank you for raising awareness about this issue.</p>
<p>Maria</p>
<p>– Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.</p>
</body>
</html>