1. Kea – Modern DHCP Engine
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Kea – Modern DHCP Engine
Open Source WG
RIPE68, Warsaw, Poland
14 May 2014
Tomek Mrugalski 1

2. Who is Tomek? M.Sc., Ph.D from Gdansk University of Technology
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Who is Tomek?
M.Sc., Ph.D from Gdansk University of Technology
Primary author of Dibbler
Portable DHCPv6 implementation (srv, cli, relay)
Supports Win 2k-Win8, Linux, BSD, Solaris
Confirmed use in 34 countries
7 years at Intel (Network Quality Labs, chipsets group)
3 years at ISC
Lead Developer of Kea (formerly BIND10 DHCP)
Occasional contributor to ISC-DHCP
Active IETF participant since 2009
DHC WG co-chair
4 RFCs, 18+ drafts (all DHCP-related) 2 2

3. ISC DHCP
Open-Source
Managed open source model (closed repository, semi-closed bug system)
First version released in 1997
Default DHCP software in many distributions
Server/relay/client for IPv4 & IPv6
Feature-rich
First version was released in V4 added IPv6 support and was released in Latest release is (released 2014).
Provides a full set of DHCP components and is the the default software in many distributions, although the client is more widely used. However, it is fair to say that the relay is perhaps not widely used, as most installations ill use the relays included in their bridges.
Lots of features. At points, the configuration file is a combination between a configuration language and procedural language.

4. Why new DHCP implementation?
Existing code is 18 years old
Networks have changed
Hardware has changed
Use cases have changed
Drawbacks with ISC DHCP
Complex code, difficult to extend
Documentation lacking
Performance not always sufficient
Partial dynamic configuration (OMAPI)
Over the years, networks have got larger and topologically more complex. In particular mobility – single client with single point of attachment. Now we have mobile devices that can move between locations. Did have networks that were flat – now we have a lot of complexity.
--BACKGROUND—
When a client moves between subnets, old lease could still be valid. Brings new requirement that keep multiple leases for same client. Another example is host reservations: in ISC DHCP these are global (as when designed there was no no mobility) and we have a reservation of one address per host. Now a reservation may cover multiple subnets if host is mobile. The old design was extended, but reservations are still a global list.
--END BACKGROUND—
Hardware has got faster and multiple cores/cpus are now common. Memory is not a limitation any more.
In short, a number of the original assumptions are no longer valid.
Mature product. Which means it’ old and has been extended many times – often without any accompanying internal documentation, a lot of which was lacking in the first place. . Which means that bits of it are, quite frankly, difficult to maintain and it is difficult to extend further. The senior developer on this product can get quite depressed if he has to work on certain parts of the code.
Another issue is performance. Some of this is down to choice of data structures within the code. Lack of encapsulation means that changes here have lots of ramifications and prone to error.

5. Kea and BIND10 history ISC has been developing BIND10 since late 2009
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Kea and BIND10 history
ISC has been developing BIND10 since late 2009
DHCP components started in mid-2011
ISC stopped BIND10 development in April 2014
=> Bundy (non-ISC,
=> Kea (ISC, 5 5

6. Kea :: Overview DHCPv4 Server DHCPv6 Server DNS Updates perfdhcp
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Kea :: Overview
DHCPv4
Server
DHCPv6
Server
DNS Updates
perfdhcp
general purpose DHCP library
IPv4/IPv6 packet parsing/assembly
IPv4/IPv6 options parsing/assembly
interface detection (Linux, partial BSD/Mac OS)
socket management
libdhcp++
Why a new version of DHCP?
Same reasons as BIND 10:
Code around for more than 10 years, world has changed
- when first written, extension of BOOTP – now a separate protocol
IPv6 is coming along
DHCP has evolved, specialised boxes, new ideas
New architecture for next 10 years
Why part of BIND 10?
Same framework:
multi process - modularity
Run-time configuration/control
Advantaged of combinging systems on same server 6 6

7. Kea :: Current status DHCPv6 DDNS Server
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Kea :: Current status
DHCPv4
Server
DDNS
DHCPv6
Server
Address assignment, renewal, release
Expiration: expired lease can be reused
Flexible option definitions
Standard options
Custom options
Nested options
Option namespaces
Vendor options (including DOCSIS3.0)
Prefix Delegation (DHCPv6)
DNS Updates (conflict resolution, no TSIG yet)
Dynamic reconfiguration (no restart needed)
Why a new version of DHCP?
Same reasons as BIND 10:
Code around for more than 10 years, world has changed
- when first written, extension of BOOTP – now a separate protocol
IPv6 is coming along
DHCP has evolved, specialised boxes, new ideas
New architecture for next 10 years
Why part of BIND 10?
Same framework:
multi process - modularity
Run-time configuration/control
Advantaged of combinging systems on same server 7 7

8. Kea :: Switchable lease database
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Kea :: Switchable lease database
Scalable
2M devices
DHCPv4/6
server
MySQL
MySQL
Can use standard tools to read/update
PostgreSQL
Can use standard tools to read/update
Performance: ??? (haven’t measured yet)
Memfile
Custom developed in C++
Flat file storage (CSV)
Offers memory-only and memory+disk-write
Very high performance (in in-memory mode), high performance in memory+disk mode)
Abstract LeaseMgr
C++ class, add your favourite storage
PgSQL
Memfile
C++
Abstract
LeaseMgr
Why a new version of DHCP?
Same reasons as BIND 10:
Code around for more than 10 years, world has changed
- when first written, extension of BOOTP – now a separate protocol
IPv6 is coming along
DHCP has evolved, specialised boxes, new ideas
New architecture for next 10 years
Why part of BIND 10?
Same framework:
multi process - modularity
Run-time configuration/control
Advantaged of combinging systems on same server 8 8

9. Hooks :: Extending the Kea server
User Library 1
Custom library1
User Library 2
Custom library2
F1()
Step A
Step B
G1()
DHCP packet processing
Step C
With hooks, users can write code that is dynamically loaded into the server (V4 and V6 – DHCP-DDNS will likely include some hooks as well). At certain points in its processing (the hooks), the server will check whether any loaded library has attached a function to that hook. If it has, the function is called. Functions can inspect and modify the data. For example, one hook is placed at the point where an incoming packet has been received and all options parsed. A hook could inspect the client identification and consult with an external database to see if a lease should be handed to it: if so, it could attach or modify options: if not, it could instruct the server to drop the packet.
As the slide suggests, multiple libraries can be loaded. If more than one library supplies a function for a hook, the system calls the functions from the libraries in the order that the libraries are loaded. It is possible to pass information from one library to another although, of course, that relies on the second library understanding information passed by the first.
Step D
F2()
G2()
Step E

10. Kea Roadmap (1) ftp://ftp.isc.org/isc/bind10/1.2.0/bind10-1.2.0.tar.gz
Kea 0.8 (April 2014)
Available now in BIND
ftp://ftp.isc.org/isc/bind10/1.2.0/bind tar.gz
Kea 0.9 (Summer 2014)
Dropping BIND 10 framework*
Configuration stored in JSON file
Keeping on-line reconfiguration (signals, better solution TBD)
Complete FreeBSD (stretch)
So where are we now:
Kea 0.8 is now out with the final release of BIND 10. This is integrated with the BIND 10 framework. In particular, configuration is via a series of commands through the command program.
Kea 0.9 is due out this summer as an independent product, without the BIND 10 superstructure. Configuration will be through a file, as is the case with ISC DHCP, although the syntax will be different.
* Details TBD, tentative plan: retain capability to build stand-alone and pluggable into Bundy framework

11. Kea Roadmap (2)
0.9
Q3 2014
1.0
Q2 2015
2.0
2015
3.0
2016
BIND10 framework removal
JSON configuration
BSD (stretch)
Host reservation
Client classification
Full lease expiration
Failover/HA solution
Statistics
MAC in DHCPv6
Reconfiguration
iPXE
External API completion
Configuration migration
Basic GUI
ISC DHCP feature uplift
ISC DHCP EOL?
Disclaimer 1: The team has not yet scoped beyond 1.0
Disclaimer 2: Dates are tentative and subject to change.2014

12. Want to help? http://kea.isc.org Kea is fully open source
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Want to help?
Kea is fully open source
Core repository is public
Bug datatase public
Mailing lists, jabber public
Test, report bugs
Contribute
Submit patches (read Contributor’s Guide first)
We are looking for sponsors (money and developers)
Development contracts
Review design documents (e.g. requirements)
Looking for contributions:
Additional back ends
Apps via Hooks API
Basic GUI … 12 12

13. 01/09/12
Thank you
kea.isc.org