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--- user_guide [2007/06/21 11:37]
morten
+++ user_guide [2011/04/08 14:02]
faltin [The back-end processes]
@@ Line 22: / Line 22: @@
 The top part of each page contains the NAV logo and a navigation bar.  The links displayed on the navigation bar are configurable per user account, by selecting the *Preferences* link.
@@ Line 48: / Line 50: @@
 | [[Arnold]]                        | Complete system for blocking access ports through SNMP write commands. |
 | [[Messages]]                      | Read and post network operational/informational messages (aka Message of the day). Messages can be related to maintenance tasks defined in the maintenance tool. |
-| [[Maintenance tasks]]             | Schedule maintenance tasks for your equipment.  The maintenance schedule is used to avoid dispatching alerts about equipment which is known to be on maintenance. |
+| [[Maintenance tasks]]             | Schedule maintenance tasks for your monitored devices.  The maintenance schedule is used to suppress alerts about devices while they are on maintenance. |
 | [[Device management]]             | Search/browse the alert history of your devices. Delete stack modules that have been physically removed from the network.  Other device lifecycle management functionality (equipment orders, errors, RMA). |
-===== The back-end processes =====
-FIXME
+====== The back-end processes ======
+NAV has several back-end processes (or services as they are sometimes called) that perform the various data collection, monitoring and administrative/maintenance tasks. Some of the processes are background daemons, while others are just cron jobs.  They can all be started and stopped individually by using the **nav** command.
+<code>
+% sudo nav
+This command is your interface to start, stop and query NAV services.
+Usage: nav [command] [service ...]
+The selected command will be applied to all known services, unless you
+specify a list of services after the command.
+Available commands are:
+  start   -- Start services.
+  stop    -- Stop services.
+  status  -- Query the status of services.
+  info    -- Display information about/description of services.
+  list    -- Display list of known services.
+  version -- Displays which version of NAV you are running.
+</code>
+All processes run as the unprivileged //navcron// user - the only exception is the //pping// process, which must be started as //root// to able to create a raw ICMP socket, and will drop privileges and run as the //navcron// user immediately after.
+These are the various services:
+^ Service              ^ Type   ^ Description ^
+| [[alertengine]]      | Daemon | Parses users' alert profiles and dispatches alerts from the global alert queue accordingly. |
+| [[cricket]]          | Cron   | 3rd party software that collects statistical data from IP devices through SNMP queries. |
+| [[eventengine]]      | Daemon | Processes events posted to NAV's internal event queue.  Translates events into alerts to post on the alert queue. |
+| [[ipdevpoll]]    | Daemon | NAV's main SNMP collection engine.  Collects just about everything except statistical data, and stores it in the NAV database.  This includes serial numbers, modules, interfaces, routing information etc. |
+| [[iptrace]]          | Cron   | Collects ARP tables from monitored routers and stores in the NAV database. |
+| [[logengine]]        | Cron   | Parses the latest syslog messages from Cisco devices on disk and stores them in the NAV database. |
+| [[mactrace]]         | Cron   | Collects CAM tables and CDP neighbors from switches.  This data is used to build the network topology.  mactrace also uses the known topology to store CAM entries for client machines on the correct access ports. |
+| [[maintengine]]      | Cron   | Effectuates the maintenance schedule by dispatching maintenance events onto the internal event queue. |
+| [[networkDiscovery]] | Cron   | Interprets the candidate topology mactrace has stored in the database, and derives the actual physical and vlan topologies of the network in a two-step process. |
+| [[pping]]            | Daemon | The parallel pinger - sends ICMP echo requests to all IP devices, waits for replies and dispatches boxState events accordingly. The daemon also records ping response time statistics using [[rrdtool]]. |
+| [[servicemon]]       | Daemon | The service monitor.  Monitors services on IP devices, such as SSH, HTTP, SMTP and others, according to the configuration entered in the [[editdb|Edit database web tool]]. Also records service response times using [[rrdtool]]. |
+| [[smsd]]             | Daemon | Dispatches SMS messages placed on the sms queue by the [[alertEngine]].  Uses dispatcher plugins to dispatch messages through various methods - most commonly by using [[Gammu]] with a locally connected mobile phone. |
+| [[thresholdMon]]     | Cron   | Monitors all known RRD files for exceeded threshold, according to user-configured thresholds, and dispatched threshold events accordingly. |

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