[master] Merged trac5390 (listen on loopback)

diff --cc doc/guide/dhcp4-srv.xml
index 83de4dadb9edb33f9ed011dfdb1d3169c55cb251,37be8932e6363940209596697605fc2dc64e7f42..b06324f4b1d86813413b7c114d35c2f7b4753448
--- 1/doc/guide/dhcp4-srv.xml
--- 2/doc/guide/dhcp4-srv.xml
+++ b/doc/guide/dhcp4-srv.xml
@@@ -773,9 -772,27 +773,27 @@@ temporarily override a list of interfac
    Note interfaces are not re-detected during <command>config-test</command>.
    </para>
  
+   <para>Usually loopback interfaces (e.g. the "lo" or "lo0" interface)
+   may not be configured but if a loopback interface is explicitely configured
+   and IP/UDP sockets are specified the loopback interface is accepted.
+   </para>
+ 
+   <para>It can be used for instance to run Kea in a FreeBSD jail having
+   only a loopback interface, servicing relayed DHCP request:
+ 
+   <screen>
+ "Dhcp4": {
+     "interfaces-config": {
+         "interfaces": [ <userinput>"lo0"</userinput> ],
+         "dhcp-socket-type": "udp"
+     },
+     ...
+ }</screen>
+   </para>
+ 
  </section>
  
 -<section id="dhcpinform-unicast-issues">
 +<section xml:id="dhcpinform-unicast-issues">
    <title>Issues with Unicast Responses to DHCPINFORM</title>
    <para>The use of UDP sockets has certain benefits in deployments
    where the server receives only relayed traffic; these benefits are

diff --cc doc/guide/dhcp6-srv.xml
index f5e1ae340eaf3aab3d7b513da3510ab09fa8b4ee,acb58b0c4fa4025fb36ab7bd03c65c238f329e79..c974e0b3ce08187d7d656d8a2dd25a9d59cb24f8
--- 1/doc/guide/dhcp6-srv.xml
--- 2/doc/guide/dhcp6-srv.xml
+++ b/doc/guide/dhcp6-srv.xml
@@@ -655,9 -654,24 +655,24 @@@ temporarily override a list of interfac
  }
    </screen>
  
+   <para>The loopback interfaces (i.e. the "lo" or "lo0" interface)
+   are not configured by default, unles explicitely mentioned in
+   the configration. Note Kea requires a link-local address which does
+   not exist on all systems, or a specified unicast address as in:
+   </para>
+ 
+   <screen>
+ "Dhcp6": {
+     "interfaces-config": {
+         "interfaces": [ <userinput>"lo/::1"</userinput> ]
+     },
+     ...
+ }
+   </screen>
+ 
  </section>
  
 -    <section id="ipv6-subnet-id">
 +    <section xml:id="ipv6-subnet-id">
        <title>IPv6 Subnet Identifier</title>
        <para>
          The subnet identifier is a unique number associated with a particular subnet.