Add rule for filtering outgoing DNS server traffic

REFERENCE.md

@@ -45,6 +45,7 @@ and Manager Daemons (MGR).
 * [`nftables::rules::out::dhcp`](#nftables--rules--out--dhcp): manage out dhcp
 * [`nftables::rules::out::dhcpv6_client`](#nftables--rules--out--dhcpv6_client): Allow DHCPv6 requests out of a host
 * [`nftables::rules::out::dns`](#nftables--rules--out--dns): manage out dns
+* [`nftables::rules::out::dnsserver`](#nftables--rules--out--dnsserver): manage outgoing DNS responses from a DNS server
 * [`nftables::rules::out::hkp`](#nftables--rules--out--hkp): allow outgoing hkp connections to gpg keyservers
 * [`nftables::rules::out::http`](#nftables--rules--out--http): manage out http
 * [`nftables::rules::out::https`](#nftables--rules--out--https): manage out https
@@ -919,6 +920,24 @@ specify dns_server name
 
 Default value: `[]`
 
+### <a name="nftables--rules--out--dnsserver"></a>`nftables::rules::out::dnsserver`
+
+manage outgoing DNS responses from a DNS server
+
+#### Parameters
+
+The following parameters are available in the `nftables::rules::out::dnsserver` class:
+
+* [`dns_servers`](#-nftables--rules--out--dnsserver--dns_servers)
+
+##### <a name="-nftables--rules--out--dnsserver--dns_servers"></a>`dns_servers`
+
+Data type: `Array[Stdlib::IP::Address]`
+
+optional list of local ip addresses from the DNS server
+
+Default value: `[]`
+
 ### <a name="nftables--rules--out--hkp"></a>`nftables::rules::out::hkp`
 
 allow outgoing hkp connections to gpg keyservers

manifests/rules/out/dnsserver.pp

@@ -0,0 +1,30 @@
+#
+# @summary manage outgoing DNS responses from a DNS server
+#
+# @param dns_servers optional list of local ip addresses from the DNS server
+#
+class nftables::rules::out::dnsserver (
+  Array[Stdlib::IP::Address] $dns_servers = [],
+) {
+  unless empty($dns_servers) {
+    $dns_servers.each |$index,$dns| {
+      $content = $dns ? {
+        Stdlib::IP::Address::V6 => "ip6 saddr ${dns}",
+        Stdlib::IP::Address::V4 => "ip saddr ${dns}",
+      }
+      nftables::rule { "default_out-dnsservertcp-${index}":
+        content => "${content} tcp sport 53 accept",
+      }
+      nftables::rule { "default_out-dnsserverudp-${index}":
+        content => "${content} udp sport 53 accept",
+      }
+    }
+  } else {
+    nftables::rule {
+      'default_out-dnsserverudp':
+        content => 'udp sport 53 accept';
+      'default_out-dnsservertcp':
+        content => 'tcp sport 53 accept';
+    }
+  }
+}

spec/acceptance/all_rules_spec.rb

@@ -48,6 +48,7 @@ class { 'nftables':
       include nftables::rules::out::postgres
       include nftables::rules::out::icmp
       include nftables::rules::out::dns
+      include nftables::rules::out::dnsserver
       include nftables::rules::out::nfs3
       include nftables::rules::out::ssh
       include nftables::rules::out::kerberos