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IKE keying daemon charon » History » Version 6

Version 5 (Martin Willi, 01.04.2008 10:06) → Version 6/19 (Martin Willi, 01.04.2008 10:50)

= IKEv2 keying daemon charon =

The ''charon'' keying daemon was built from scratch to implement the IKEv2 protocol for strongSwan.
It has a fully multi-threaded design to meet todays requirements.

== Architecture ==
{{{
+---------------------------------+ +----------------------------+
| Credentials | | Backends |
+---------------------------------+ +----------------------------+

+------------+ +-----------+ +------+ +----------+
| receiver | | | | | +------+ | CHILD_SA |
+----+-------+ | Scheduler | | IKE- | | IKE- |--+----------+
| | | | SA |--| SA | | CHILD_SA |
+-------+--+ +-----------+ | | +------+ +----------+
<->| socket | | | Man- |
+-------+--+ +-----------+ | ager | +------+ +----------+
| | | | | | IKE- |--| CHILD_SA |
+----+-------+ | Processor |--------| |--| SA | +----------+
| sender | | | | | +------+
+------------+ +-----------+ +------+

+---------------------------------+ +----------------------------+
| Bus | | Kernel Interface |
+---------------------------------+ +----------------------------+
| | |
+-------------+ +-------------+ V
| File-Logger | | Sys-Logger | //////
+-------------+ +-------------+
}}}

||'''Processor'''||The threading is realized with the help of a thread pool (called processor), which contains a fixed amount of precreated threads. All threads in the daemon originate from the processor. To delegate work to a thread, jobs are queued to the processor for asynchronous execution.||
||'''Scheduler'''||The scheduler is responsible to execute timed events. Jobs may be queued to the scheduler to get executed at a defined time (e.g. rekeying). The scheduler does not execute the jobs itself, it queues them to the processor.||
||'''IKE_SA Manager'''||The IKE_SA manager managers all IKE_SA. It further handles the synchronization: Each IKE_SA must be checked out strictly and checked in again after use. The manager guarantees that only one thread may check out a single IKE_SA. This allows us to write the (complex) IKE_SAs routines non-threadsave.||
||'''IKE_SA'''||The IKE_SA contain the state and the logic of each IKE_SA and handle the messages.||
||'''CHILD_SA'''||The CHILD_SA contains state about a IPsec security association and manages them. An IKE_SA may have multiple CHILD_SAs. Communication to the kernel takes place here through the kernel interface.||
||'''Kernel Interface'''||The kernel interface installs IPsec security associations, policies routes and virtual addresses. It further provides methods to numerate interfaces and may notify the daemon about state changes at lower layers. ||
||'''Bus'''||The bus receives signals from the different threads and relais them to interested listeners. Debugging signals, but also important state changes or error messages are sent over the bus.||
||'''Controller'''||The controller provides a simple API for plugins to control the daemon (e.g. initiate IKE_SA, close IKE_SA, ...).||
||'''Backends'''||Backends are pluggable modules which provide configuration. They have to implement an API which the daemon core uses to get configuration.

== Plugins ==

The daemon loads plugins at startup. These implement the [browser:trunk/src/libstrongswan/plugins/plugin.h plugin_t] interface. Each plugin registers itself at the daemon to hook in functionality.

{{{
+-------------------------------------+
| charon +---+ +-----+------+
| | | | stroke |
| | | +-----+------+
| +-------------+ | | +-----+------+
| | bus | ----> | p | | smp |
| +-------------+ | l | +-----+------+
| +-------------+ <---- | u | +-----+------+
| | controller | | g | | sql |
| +-------------+ ----> | i | +-----+------+
| +-------------+ | n | +-----+------+
| | credentials | <---- | | | eap_aka |
| +-------------+ | l | +-----+------+
| +-------------+ ----> | o | +-----+------+
| | backends | | a | | eap_sim |
| +-------------+ <---- | d | +-----+------+
| +-------------+ | e | +-----+------+
| | eap | ----> | r | | eap_md5 |
| +-------------+ | | +-----+------+
| | | +-----+------+
| | | |eap_identity|
| +---+ +-----+------+
+-------------------------------------+
}}}

There is a growing list of available plugins:
||[browser:trunk/src/charon/plugins/stroke stroke]||The ||'''stroke'''||The stroke plugin loads credentials from ''/etc/ipsec.d'', reads ''ipsec.secrets'' and accepts configurations and control commands from ipsec starter.||
||[browser:trunk/src/charon/plugins/smp smp]||The ||'''smp'''||The smp plugin implements the [wiki:SMP] protocol to control and query the daemon using an XML interface.||
||[browser:trunk/src/charon/plugins/sql sql]||The ||'''sql'''||The sql plugin provides credentials and configurations from a relational database, see [wiki:SQL].||
||[browser:trunk/src/charon/plugins/eap_aka eap_aka]||Implements ||'''eap_aka'''||Implements the AKA EAP module implemented completely in software.||
||[browser:trunk/src/charon/plugins/eap_sim eap_sim]||Implements ||'''eap_sim'''||Implements the SIM EAP module using either a triplet file or a third party card reader library.||
||[browser:trunk/src/charon/plugins/eap_md5 eap_md5]||Implements ||'''eap_md5'''||Implements the MD5 EAP module (CHAP).||
||[browser:trunk/src/charon/plugins/eap_identity eap_identity]||EAP ||'''eap_identity'''||EAP helper module to serve an Identity over EAP before doing EAP authentication.||