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Commit 4f0fc2f4 authored by Shawn Routhier's avatar Shawn Routhier
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[trac4101] Update per review comments 

Notable items:
Removed a lot of the classification text from dhcp4.xml and dhcp6.xml
leaving a brief description with a pointer to the main text and some
examples.

Added more examples
parent 8d87f8f5
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doc/guide/classify.xml
View file @ 4f0fc2f4
......@@ -32,8 +32,8 @@
It is envisaged that client classification will be used for changing the
behavior of almost any part of the DHCP message processing, including the assignment of
leases from different pools, the assignment of different options (or different values of
the same options) etc. In the current release of the software however, there are only three
mechanisms that take
the same options) etc. In the current release of the software however, there are
only three mechanisms that take
advantage of client classification: subnet selection, assignment of different
options and, for DHCPv4 cable modems, the setting of specific options for use with
the TFTP server address and the boot file field.
......@@ -58,7 +58,7 @@
When determining which options to include in the response the server will examine
the union of options from all of the assigned classes. In the case two or more
classes include the same option, the value from the first class examined will
be used. Similarly if two or more classes are associated with a subnet, the
be used. Similarly if two or more classes are associated with subnets, the
first class examined will be used. In the future the processing order of the
various classes may be specified but for now it is being left unspecified and
may change in future releases.
......@@ -201,17 +201,47 @@
</tgroup>
</table>
The substring operator "substring(value, start, length)" accepts both positive and
negative values for the starting position and the length. For "start", a value of
0 is the first byte in the string while -1 is the last byte. If the starting
point is outside of the original string an empty string is returned. "length"
is the number of bytes to extract. A negative number means to count towards
the beginning of the string but doesn't include the byte pointed to by "start".
The special value "all" means to return all bytes from start to the end of the
string. If length is longer than the remaining portion of the string then
the entire remaining portion is returned.
<section>
<title>Substring</title>
The substring operator "substring(value, start, length)" accepts both positive and
negative values for the starting position and the length. For "start", a value of
0 is the first byte in the string while -1 is the last byte. If the starting
point is outside of the original string an empty string is returned. "length"
is the number of bytes to extract. A negative number means to count towards
the beginning of the string but doesn't include the byte pointed to by "start".
The special value "all" means to return all bytes from start to the end of the
string. If length is longer than the remaining portion of the string then
the entire remaining portion is returned. Some examples may be helpful:
<itemizedlist>
<listitem><para>
substring('foobar', 0, 6) == 'foobar'
</para></listitem>
<listitem><para>
substring('foobar', 3, 3) == 'bar'
</para></listitem>
<listitem><para>
substring('foobar', 3, all) == 'bar'
</para></listitem>
<listitem><para>
substring('foobar', 1, 4) == 'ooba'
</para></listitem>
<listitem><para>
substring('foobar', -5, 4) == 'ooba'
</para></listitem>
<listitem><para>
substring('foobar', -1, -4) == 'ooba'
</para></listitem>
<listitem><para>
substring('foobar', 5, -4) == 'ooba'
</para></listitem>
<listitem><para>
substring('foobar', 10, 2) == ''
</para></listitem>
</itemizedlist>
</section>
</para>
</section>
</section>
<note>
<para>
......@@ -242,9 +272,14 @@
</para>
<para>
In the following example the class named &quot;Client_foo&quot; is defined.
It is comprised of all clients who's client ids (option 61) start with the
string &quot;foo&quot;. Members of this class will be given 192.0.2.1 and
192.0.2.2 as their domain name servers.
<screen>
"Dhcp4": {
"client-class": [<userinput>
"client-classes": [<userinput>
{
"name": "Client_foo",
"test": "substring(option[61].text,0,3) == 'foo'",
......@@ -265,10 +300,31 @@
</para>
<para>
In this example the class named &quot;Client_foo&quot; is defined. It is comprised
of all clients who's client ids (option 61) start with the string &quot;foo&quot;.
Members of this class will be given 192.0.2.1 and 192.0.2.2 as their domain name
servers.
This example shows a client class being defined for use by the DHCPv6 server.
In it the class named &quot;Client_enterprise&quot; is defined. It is comprised
of all clients who's client identifiers start with the given hex string (which
would indicate a DUID based on an enterprise id of 0xAABBCCDD). Members of this
class will be given an 2001:db8:0::1 and 2001:db8:2::1 as their domain name servers.
<screen>
"Dhcp6": {
"client-classes": [<userinput>
{
"name": "Client_enterprise",
"test": "substring(option[2].hex,0,6) == 0x0002AABBCCDD'",
"option-data": [
{
"name": "dns-servers",
"code": 23,
"space": "dhcp6",
"csv-format": true,
"data": "2001:db8:0::1, 2001:db8:2::1"
}
]
},
...
],</userinput>
...
}</screen>
</para>
</section>
......@@ -276,7 +332,11 @@
<title>Configuring Subnets With Class Information</title>
<para>
In certain cases it beneficial to restrict access to certain subnets
only to clients that belong to a given class.
only to clients that belong to a given class using the "client-class"
keyword when defining the subnet.
</para>
<para>
Let's assume that the server is connected to a network segment that uses
the 192.0.2.0/24 prefix. The Administrator of that network has decided
that addresses from range 192.0.2.10 to 192.0.2.20 are going to be
......@@ -285,7 +345,7 @@
configuration can be achieved in the following way:
<screen>
"Dhcp4": {
"client-class": [
"client-classes": [
{
"name": "Client_foo",
"test": "substring(option[61].text,0,3) == 'foo'",
......@@ -306,8 +366,43 @@
"subnet": "192.0.2.0/24",
"pools": [ { "pool": "192.0.2.10 - 192.0.2.20" } ],
"client-class": "Client_foo"
},
...
],</userinput>,
...
}</screen>
</para>
<para>
The following example shows restricting access to a DHCPv6 subnet. This
configuration will restrict use of the addresses 2001:db8:1::1 to
2001:db8:1::FFFF to members of the "Client_enterprise" class.
<screen>
"Dhcp6": {
"client-classes": [
{
"name": "Client_enterprise",
"test": "substring(option[2].hex,0,6) == 0x0002AABBCCDD'",
"option-data": [
{
"name": "dns-servers",
"code": 23,
"space": "dhcp6",
"csv-format": true,
"data": "2001:db8:0::1, 2001:db8:2::1"
}
]
},
...
], <userinput>
"subnet6": [
{
"subnet": "2001:db8:1::/64",
"pools": [ { "pool": "2001:db8:1::-2001:db8:1::ffff" } ],
"client-class": "Client_enterprise"
}
]</userinput>,
],</userinput>
...
}</screen>
</para>
......
doc/guide/dhcp4-srv.xml
View file @ 4f0fc2f4
......@@ -1567,14 +1567,26 @@ It is merely echoed by the server
<para>
In certain cases it is useful to differentiate between different types of
clients and treat them accordingly. It is envisaged that client classification
will be used for changing the
behavior of almost any part of the DHCP message processing, including assigning
leases from different pools, assigning different options (or different values of
the same options) etc. For now, there are only three mechanisms that are taking
advantage of client classification: subnet seletion, assigning different options,
and for cable modems there are specific options for use with the TFTP
server address and the boot file field.
clients and treat them accordingly. It is envisaged that client
classification will be used for changing the behavior of almost any part of
the DHCP message processing, including the assignment of leases from different
pools, the assignmen of different options (or different values of the same
options) etc. In the current release of the software however, there are
only three mechanisms that take advantage of client classification:
subnet seletion, assignment of different options, and, for cable modems, there
are specific options for use with the TFTP server address and the boot file field.
</para>
<para>
Kea can be instructed to limit access to given subnets based on class information.
This is particularly useful for cases where two types of devices share the
same link and are expected to be served from two different subnets. The
primary use case for such a scenario is cable networks. There are two
classes of devices: the cable modem itself, which should be handed a lease
from subnet A and all other devices behind the modem that should get a lease
from subnet B. That segregation is essential to prevent overly curious
users from playing with their cable modems. For details on how to set up
class restrictions on subnets, see <xref linkend="classification-subnets"/>.
</para>
<para>
......@@ -1594,18 +1606,6 @@ It is merely echoed by the server
a member of the class.
</para>
<para>
Kea can be instructed to limit access to given subnets based on class information.
This is particularly useful for cases where two types of devices share the
same link and are expected to be served from two different subnets. The
primary use case for such a scenario is cable networks. There are two
classes of devices: the cable modem itself, which should be handed a lease
from subnet A and all other devices behind the modem that should get a lease
from subnet B. That segregation is essential to prevent overly curious
users from playing with their cable modems. For details on how to set up
class restrictions on subnets, see <xref linkend="dhcp4-subnet-class"/>.
</para>
<note><para>
Care should be taken with client classification as it is easy for
clients that do not meet class criteria to be denied any service altogether.
......@@ -1632,51 +1632,20 @@ It is merely echoed by the server
</section>
<section>
<title>Using Expressions in Classification</title>
<para>
The expression portion of classification contains operators and values.
Values are currently strings and operators take a string or strings and
return another string. When all the operations have completed
the result should be a value of &quot;true&quot; or &quot;false&quot;.
The packet belongs to
the class (and the class name is added to the list of classes) if the result
is &quot;true&quot;. Expressions are written in standard format and can be nested.
For more information about expressions see
<xref linkend="classification-using-expressions"/>
</para>
</section>
<section>
<title>Configuring Classes</title>
<para>
A class contains three items: a name, a test expression and option data.
The name must exist and must be unique amongst all classes. The test
expression and option data are optional.
</para>
<para>
The test expression is a string containing the logical expression used to
determine membership in the class. The entire expression is in double
quotes.
</para>
<title>Configuring Classes Example</title>
<para>
The option data is a list which defines any options that should be assigned
to members of this class.
</para>
The following example shows how to configure a class using an expression
and a subnet making use of that class. This configuration defines the
class named &quot;Client_foo&quot;.
It is comprised of all clients who's client ids (option 61) start with the
string &quot;foo&quot;. Members of this class will be given addresses from
192.0.2.10 to 192.0.2.20 and 192.0.2.1 and 192.0.2.2 as their domain name
servers. For a deeper discussion of the classification process see
<xref linkend="classify"/>.
<para>
<screen>
"Dhcp4": {
"subnet4": [
{
"subnet": "192.0.2.0/24",
"pools": [ { "pool": "192.0.2.10 - 192.0.2.20" } ],
"client-class": "Client_foo"
}
],
"client-class": [
<userinput>
"client-classes": [
{
"name": "Client_foo",
"test": "substring(option[61].text,0,3) == 'foo'",
......@@ -1689,40 +1658,35 @@ It is merely echoed by the server
"data": "192.0.2.1, 192.0.2.2"
}
]
}
</userinput>
},
...
],
"subnet4": [
{
"subnet": "192.0.2.0/24",
"pools": [ { "pool": "192.0.2.10 - 192.0.2.20" } ],
"client-class": "Client_foo"
},
...
],
...
}</screen>
</para>
<para>
In this example the class named &quot;Client_foo&quot; is defined. It is comprised
of all clients who's client ids (option 61) start with the string &quot;foo&quot;.
They will be given an address from 192.0.2.10 to 192.0.2.20 and 192.0.2.1
and 192.0.2.2 as their domain name servers.
</para>
</section>
This example shows a configuration using an automatcially generated
"VENDOR_CLASS_" class. The Administrator of the network has
decided that addresses from range 192.0.2.10 to 192.0.2.20 are
going to be managed by the Dhcp4 server and only clients belonging to the
docsis3.0 client class are allowed to use that pool.
<section id="dhcp4-subnet-class">
<title>Limiting Access to IPv4 Subnet to Certain Classes</title>
<para>
In certain cases it beneficial to restrict access to certain subnets
only to clients that belong to a given subnet. For details on client
classes, see <xref linkend="dhcp4-client-classifier"/>. This is an
extension of a previous example from <xref linkend="dhcp4-address-config"/>.
Let's assume that the server is connected to a network segment that uses
the 192.0.2.0/24 prefix. The Administrator of that network has decided
that addresses from range 192.0.2.10 to 192.0.2.20 are going to be
managed by the Dhcp4 server. Only clients belonging to client class
VENDOR_CLASS_docsis3.0 are allowed to use this subnet. Such a
configuration can be achieved in the following way:
<screen>
"Dhcp4": {
"subnet4": [
{
<userinput>"subnet": "192.0.2.0/24",
"subnet": "192.0.2.0/24",
"pools": [ { "pool": "192.0.2.10 - 192.0.2.20" } ],
"client-class": "VENDOR_CLASS_docsis3.0"</userinput>
<userinput>"client-class": "VENDOR_CLASS_docsis3.0"</userinput>
}
],
...
......@@ -2770,7 +2734,7 @@ It is merely echoed by the server
<para>
In certain cases, it is useful to mix relay address information,
introduced in <xref linkend="dhcp4-relay-override"/> with client
classification, explained in <xref linkend="dhcp4-subnet-class"/>.
classification, explained in <xref linkend="classify"/>.
One specific example is cable network, where typically modems
get addresses from a different subnet than all devices connected
behind them.
......
doc/guide/dhcp6-srv.xml
View file @ 4f0fc2f4
......@@ -1555,13 +1555,25 @@ should include options from the isc option space:
<para>
In certain cases it is useful to differentiate between different types
of clients and treat them differently. It is envisaged that the client
classification will be used for changing the
behavior of almost any part of the DHCP engine processing, including assigning
leases from different pools, assigning different option (or different values of
the same options) etc. For now, there are only two mechanisms that are taking
advantage of client classification: subnet selection and assigning differnet
options.
of clients and treat them accordingly. It is envisaged that client
classification will be used for changing the behavior of almost any part of
the DHCP message processing, including the assignement of leases from different
pools, the assigment of different options (or different values of the same
options) etc. In the current release of the sofware however, there are
only two mechanisms that take advantage of client classification:
subnet selection and assignment of differnet options.
</para>
<para>
Kea can be instructed to limit access to given subnets based on class information.
This is particularly useful for cases where two types of devices share the
same link and are expected to be served from two different subnets. The
primary use case for such a scenario is cable networks. There are two
classes of devices: the cable modem itself, which should be handed a lease
from subnet A and all other devices behind the modem that should get a lease
from subnet B. That segregation is essential to prevent overly curious
users from playing with their cable modems. For details on how to set up
class restrictions on subnets, see <xref linkend="classification-subnets"/>.
</para>
<para>
......@@ -1581,80 +1593,26 @@ should include options from the isc option space:
a member of the class.
</para>
<para>
Kea can be instructed to limit access to given subnets based on class information.
This is particularly useful for cases where two types of devices share the
same link and are expected to be served from two different subnets. The
primary use case for such a scenario is cable networks. There are two
classes of devices: the cable modem itself, which should be handed a lease
from subnet A and all other devices behind the modem that should get a lease
from subnet B. That segregation is essential to prevent overly curious
users from playing with their cable modems. For details on how to set up
class restrictions on subnets, see <xref linkend="dhcp6-subnet-class"/>.
</para>
<note><para>
Care should be taken with client classification as it is easy for
clients that do not meet class criteria to be denied any service altogether.
</para></note>
<section>
<title>Using Vendor Class Information in Classification</title>
<para>
The server checks whether an incoming packet includes the vendor class
option (16). If it does, the content of that option is prepended with
&quot;VENDOR_CLASS_&quot; then it is interpreted as a class. For example,
modern cable modems will send this option with value &quot;docsis3.0&quot;
and as a result the packet will belong to class &quot;VENDOR_CLASS_docsis3.0&quot;.
</para>
</section>
<section>
<title>Using Expressions in Classification</title>
<para>
The expression portion of classification contains operators and values.
Values are currently strings and operators take a string or strings and
return another string. When all the operations have completed
the result should be a value of &quot;true&quot; or &quot;false&quot;.
The packet belongs to
the class (and the class name is added to the list of classes) if the result
is &quot;true&quot;. Expressions are written in standard format and can be nested.
For more information about expressions see
<xref linkend="classification-using-expressions"/>
</para>
</section>
<section>
<title>Configuring Classes</title>
<title>Configuring Classes Example</title>
<para>
A class contains three items: a name, a test expression and option data.
The name must exist and must be unique amongst all classes. The test
expression and option data are optional.
</para>
<para>
The test expression is a string containing the logical expression used to
determine membership in the class. The entire expression is in double
quotes.
</para>
<para>
The option data is a list which defines any options that should be assigned
to members of this class.
</para>
The following example shows how to configure a class using an expression
and a subnet making use of that class. This configuration defines the
class named &quot;Client_enterprise&quot;. It is comprised
of all clients who's client identifiers start with the given hex string (which
would indicate a DUID based on an enterprise id of 0xAABBCCDD).
They will be given an address from 2001:db8:1::0 to 2001:db8:1::FFFF and
2001:db8:0::1 and 2001:db8:2::1 for their domain name servers. For a deeper
discussion of the classification process see <xref linkend="classify"/>.
<para>
<screen>
<screen>
"Dhcp6": {
"subnet6": [
{
"subnet": "2001:db8:1::/64",
"pools": [ { "pool": "2001:db8:1::-2001:db8:1::ffff" } ],
"client-class": "Client_enterprise"
}
],
"client-class": [
<userinput>
"client-classes": [
{
"name": "Client_enterprise",
"test": "substring(option[2].hex,0,6) == 0x0002AABBCCDD'",
......@@ -1667,35 +1625,26 @@ should include options from the isc option space:
"data": "2001:db8:0::1, 2001:db8:2::1"
}
]
},
...
],
"subnet6": [
{
"subnet": "2001:db8:1::/64",
"pools": [ { "pool": "2001:db8:1::-2001:db8:1::ffff" } ],
"client-class": "Client_enterprise"
}
</userinput>
],
...
}</screen>
</para>
<para>
In this example the class named &quot;Client_foo&quot; is defined. It is comprised
of all clients who's client identifiers start with the given hex string (which
would indicate a DUID based on an enterprise id of 0xAABBCCDD).
They will be given an address from 2001:db8:1::0 to 2001:db8:1::FFFF and
2001:db8:0::1 and 2001:db8:2::1 their domain name servers.
</para>
</section>
</para>
<section id="dhcp6-subnet-class">
<title>Limiting access to IPv6 subnet to certain classes</title>
<para>
In certain cases it beneficial to restrict access to certain subnets
only to clients that belong to a given class. For details on client
classes, see <xref linkend="dhcp6-client-classifier"/>. This is an
extension of a previous example from <xref linkend="dhcp6-address-config"/>.
Let's assume that the server is connected to a network segment that uses
the 2001:db8:1::/64 prefix. The Administrator of that network has
decided that addresses from range 2001:db8:1::1 to 2001:db8:1::ffff are
going to be managed by the Dhcp6 server. Only clients belonging to the
eRouter1.0 client class are allowed to use that pool. Such a
configuration can be achieved in the following way:
<para>
This example shows a configuration using an automatcially generated
"VENDOR_CLASS_" class. The Administrator of the network has
decided that addresses from range 2001:db8:1::1 to 2001:db8:1::ffff are
going to be managed by the Dhcp6 server and only clients belonging to the
eRouter1.0 client class are allowed to use that pool.
<screen>
"Dhcp6": {
......@@ -2614,7 +2563,7 @@ should include options from the isc option space:
<para>
In certain cases, it is useful to mix relay address information,
introduced in <xref linkend="dhcp6-relay-override"/> with client
classification, explained in <xref linkend="dhcp6-subnet-class"/>.
classification, explained in <xref linkend="classify"/>.
One specific example is a cable network, where typically modems
get addresses from a different subnet than all devices connected
behind them.
......
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