diff --git a/src/test/setup/radius-config/freeradius/mods-available/idn b/src/test/setup/radius-config/freeradius/mods-available/idn
new file mode 100644
index 0000000..31874c5
--- /dev/null
+++ b/src/test/setup/radius-config/freeradius/mods-available/idn
@@ -0,0 +1,28 @@
+# -*- text -*-
+#
+#  $Id: 534054077d52a7bb0bf8e02c1e861e5c86b76df9 $
+
+#
+# Internationalised domain names.
+#
+
+#  The expansion string: %{idn: example.com} results in an ASCII
+#  punycode version of the domain name.  That version can then be used
+#  for name comparisons.  Using an i18n version of the name is NOT
+#  RECOMMENDED, as that version is not canonical.
+#
+#  i.e. the "same" domain name can be represented in many, many,
+#  different ways.  Only the idn version has *one* representation.
+#
+idn {
+	#
+	#  Allow use of unassigned Unicode code points.
+	#
+	allow_unassigned = no
+
+	#
+	#  Prohibit underscores and other invalid characters in domain
+	#  names.
+	use_std3_ascii_rules = yes
+
+}
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