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Optimisacion del ancho de bandaMonitoreo/Nagios
Christian Benvenutichristian.benvenuti@libero.it
Managua, Nicaragua, 1-5/3/2010
UNAN-Managua
Before we start ...
● Have you ever used Nagios?● Have you ever installed Nagios?
● How? (tarball or via GUI)● If yes, can you remember any specific problem you
had to resolve?
● What kind of monitoring information can Nagios provide? (examples)
● What kind of monitoring information can't Nagios provide? (examples)
Schedule● Introduction to the class of network monitoring
features provided by Nagios● Architectural overview: object types and
relationships, etc● Overview of basic features and examples of
configurations● Overview of more advanced features and
examples of configurations● Installation and basic configuration● Exercises
Basic Features● Object types and relationships
● Hosts vs Services● Host groups, Service groups
● Contacts and notifications● Contact groups, escalations
● Templates● Object Dependencies● Templates and Object Inheritance● Passive checks and NCSA (quick intro)● Management (Web Interface)
I know thisalready (Y/N)
Advanced features
● Nagios Check Service Acceptor (NCSA)● Remote monitoring
● Nagios Remote Plugin Executor (NRPE)● Simple Network Management Protocol (SNMP)
I know thisalready
Probably tomorrow, together with MRTG & Cacti
OPTIONAL(time permitting)
Functionalities Overview● What do we want/need to monitor?● What do we want/need to do with the information
returned by the monitoring process?● What if a host is down?● What if the web server is UP (=reachable) but not
working properly?
● How would the organization of the monitoring configuration change when applied to a big network?● Scalability● Easiness of upgrade/troubleshooting● etc
Example
Nagios
Internet
WWW Mail
...
PC1 PCn
...
Admin1
Admin2
Suporte tecnico
...
DHCP
How would I write (in plain English orSpanish) the monitoring rules/configthat would simplify the admin's life?
Object types
● Monitored object types:● Hosts (routers, switches, servers, ...)● Services (www, dhcp, ftp, ssh, ...)● Derived monitored object types
– Host groups– Service groups
● Xxx object types:● Contacts and Contact Groups● Time periods● Commands
Host vs Service
Nagios
Internet
WWW Mail
...
PC1 PCn
...
Admin1
Admin2
Suporte tecnico
...
DHCP
Is this ahost or a service?
What is this?
And this?
What's the difference between hosts and services?
TCP/IP stack
Applications
WE
B s
erve
r
Em
ail s
erve
r
DN
S s
erve
r
...
host
services
This rule does not apply always.Example?
SS
HD
ser
ver
Object type: host
define host {
host_name default_gw
alias default gateway
address 10.0.1.1
...
}
10.0.1.1/24
10.0.1.100/24
NagiosInternet
gw.mynet.edu
Object type: host
define host {
}
host_name default_gwalias default_gatewayaddress 10.0.1.1...
... check parameters ...
... contact/notificationparameters ...
check_commandcheck_intervalretry_intervalmax_check_attemptscheck_period
Object type: host
define host {
}
host_name default_gwalias default_gatewayaddress 10.0.1.1...
... check parameters ...
... contact/notificationparameters ...
contactscontact_groupsfirst_notification_delaynotification_intervalnotification_periodnotification_options
Object type: hostExample
define host {
host_name default_gw
alias default gateway
address 10.0.1.1
check_command check-host-alive
check_interval 5
retry_interval 1
max_check_attempts 5
check_period 24x7
contacts admin@xxxuniv.edu.ni
notification_interval 60
notification_period 24x7
notification_options d,u,r
}
Object type: hostExample
define host {
host_name default_gw
alias default gateway
address 10.0.1.1
check_command check-host-alive
check_interval 5
retry_interval 1
max_check_attempts 5
check_period 24x7
contacts admin@xxxuniv.edu.ni
notification_interval 60
notification_period 24x7
notification_options d,u,r
}
define host { host_name router_eng alias Router for the Engineering campus address 10.0.1.1 ...}define host { host_name router_law alias Router for the Law campus address 10.0.2.1 ...}define host { host_name router_art alias Router for the Art campus address 10.0.3.1 ...}
Eng
Law
Art
10.0.1.2
10.0.1.3
10.0.1.4
Nagios
Internet
10.0.1.1
Nagios
Nagios
define host { host_name router_eng alias Router for the Engineering campus address 10.0.1.1 ...}define host { host_name router_law alias Router for the Law campus address 10.0.2.1 ...}define host { host_name router_art alias Router for the Art campus address 10.0.3.1 ...}
Eng
Law
Art
10.0.1.2
10.0.1.3
10.0.1.4
Internet
10.0.1.1
Nagios
define host {
host_name router_eng
alias Router for the Engineering campus
address 10.0.1.1
...
}
define host {
host_name router_law
alias Router for the Law campus
address 10.0.1.2
...
}
define host {
host_name router_art
alias Router for the Art campus
address 10.0.1.3
...
}
define hostgroup {
hostgroup_name campus_routers
alias All the routers that connect the university campuses
members router_art, router_law, router_eng
}
Object type: hostgroup
define host { host_name router_eng alias Router for the Engineering campus address 10.0.1.1 ...}define host { host_name router_law alias Router for the Law campus address 10.0.2.1 ...}define host { host_name router_art alias Router for the Art campus address 10.0.3.1 ...}
Eng
Law
Art
10.0.1.2
10.0.1.3
10.0.1.4
Internet
10.0.1.1
Nagios
define host {
host_name router_eng
alias Router for the Engineering campus
address 10.0.1.2
...
}
define host {
host_name router_law
alias Router for the Law campus
address 10.0.1.3
...
}
define host {
host_name router_art
alias Router for the Art campus
address 10.0.1.4
...
}
define hostgroup {
hostgroup_name campus_routers
alias All the routers that connect the university campuses
members 10.0.2.1, 10.0.3.1, 10.0.4.1
}
Is this config correct?
define host { host_name router_eng alias Router for the Engineering campus address 10.0.1.1 ...}define host { host_name router_law alias Router for the Law campus address 10.0.2.1 ...}define host { host_name router_art alias Router for the Art campus address 10.0.3.1 ...}
Eng
Law
Art
10.0.1.2
10.0.1.3
10.0.1.4
Internet
10.0.1.1
Nagios
define host {
host_name router_eng
alias Router for the Engineering campus
address 10.0.2.1
...
}
define host {
host_name router_law
alias Router for the Law campus
address 10.0.3.1
...
}
define host {
host_name router_art
alias Router for the Art campus
address 10.0.4.1
...
}
define hostgroup {
hostgroup_name campus_routers
alias All the routers that connect the university campuses
members router_eng, router_law, router_art
}
Is this config correct?
define host { host_name router_eng alias Router for the Engineering campus address 10.0.1.1 ...}define host { host_name router_law alias Router for the Law campus address 10.0.2.1 ...}define host { host_name router_art alias Router for the Art campus address 10.0.3.1 ...}
Eng
Law
Art
10.0.1.2
10.0.1.3
10.0.1.4
Internet
10.0.1.1
Nagios
define host {
host_name router_eng
alias Router for the Engineering campus
address 10.0.1.2
...
}
define host {
host_name router_law
alias Router for the Law campus
address 10.0.1.3
...
}
define host {
host_name router_art
alias Router for the Art campus
address 10.0.1.4
...
}
define hostgroup {
hostgroup_name campus_routers
alias All the routers that connect the university campuses
members router_eng, router_law, router_art
}
Is this config correct?
define host { host_name router_eng alias Router for the Engineering campus address 10.0.1.1 ...}define host { host_name router_law alias Router for the Law campus address 10.0.2.1 ...}define host { host_name router_art alias Router for the Art campus address 10.0.3.1 ...}
Eng
Law
Art
10.0.1.2
10.0.1.3
10.0.1.4
Internet
10.0.1.1
Nagios
define host {
host_name router_eng
alias Router for the Engineering campus
address 10.0.1.2
...
}
define host {
host_name router_law
alias Router for the Law campus
address 10.0.1.3
...
}
define host {
host_name router_art
alias Router for the Art campus
address 10.0.1.4
...
}
define hostgroup {
hostgroup_name campus_routers
alias All the routers that connect the university campuses
Members router_eng, router_law, router_art
}
Is this config correct?
Examples of Host Groups
hostgroup windows_lab hostgroup linux_lab
Examples of Host Groups
hostgroup servidores_web hostgroup servidores_correo
WEB Correo WEB Correo
Campus A Campus B
... ...
Hosts vs Services
WEB Correo
Campus A
...
Nagios
10.0.1.100 10.0.1.101
define host { host_name Campus_A_WEB alias Servidor Web Campus A address 10.0.1.100 check_command check_host_alive ...}define host { host_name Campus_A_CORREO alias Servideor Correo Campus A address 10.0.1.101 check_command check_host_alive ...}
Is this sufficient to monitor the two Web/Mail servers?
Object type: servicedefine host { host_name web_server alias WEB server address 10.0.1.100 ...}
define service { host_name web_server , ... service_description WEB server check_command check_http ...}
Nagios
Internet
10.0.1.100
WWW
...
...
Object type: service
define service {
}
host_name default_gwalias default_gatewayaddress 10.0.1.1...
... check parameters ...
... contact/notificationparameters ...
check_commandcheck_intervalretry_intervalmax_check_attemptscheck_period
Hosts vs Services
define host {
}
host_name alias address ...
... check parameters ...(check_command, etc)
... contact/notificationparameters ...(contacts, etc)
host_name service_description...
... check parameters ...(check_command, etc)
... contact/notificationparameters ...(contacts, etc)
define service {
}
Object type: servicegroup
define servicegroup {
servicegroup_name web_servers
alias todos los servidores we
members host1,service1, host2,service2, ...
...
}
Example of service group
define host {
host_name www_unan_managua
alias UNAN Managua web server
address www.unan.edu.ni
...
}
define host {
host_name ftp_unan_leon
alias UNAN Managua ftp server
address ftp.unan.edu.ni
...
}
define servicet {
host_name www_unan_managua
service_description www
check_command check_http
...
}
define service {
host_name ftp_unan_managua
service_description ftp
check_command check_ftp
...
}
define service_group {
servicegroup_name services_unan_managua
alias servicios publicos ofrecidos por UNAN Managua
members www_unan_managua,www, ftp_unan_managua,ftp
...
}
Plugins:parameter check_command
● Host plugins● check_host_alive
● Service plugins● check_http● check_dns● check_dhcp● ...
Object type: (check) commands
define command {
command_name .........
command_line .........
}
Example from /etc/nagios/objects/commands.cfg:
define command { command_name check_http command_line $USER1$/check_http -I \ $HOSTADDRESS$ $ARG1$ }
Object type: (check) commands
define command { command_name check_http command_line $USER1$/check_http -I \ $HOSTADDRESS$ $ARG1$ }
USER MACRO(See resources.cfg)
Pre-defines MACROs
Is this a chicken-egg problem?
There are other typesof macro too (see
on-demand macros)
Notifications
Contacts Notifications
What? When? How?
Notifications
● When there is a problem● Do you think the more people receive a notification
and the better it is?● Do you think an email is sufficient to tell/notify the
owner of a service/host about a problem?● How do you handle cases where it is not clear who
the best contact person/s is/are?– This may not be an issue when there is lack of personal
and everybody takes care of everything. Does this sound like a familiar situation to you :-) ?
Notifications
InstantMessaging
Pager
SMS
How good are emailsfor urgent problems?
Are these a good option fornotifications generated duringthe night?
It depends!
NotificationsEscalations
Nagios
Internet
10.0.1.100
WWW
X
...
Escalation
Parameters check_period and notification_period
● check_period● Name of the time period during which Nagios
should check the host/service status.● notification_period
● Name of the time period during which Nagios should generate notifications if necessary (according to the config).
● Same syntax (= object timeperiod)
define timeperiod { timeperiod_name <name> alias <description> ... } See file /etc/nagios/objects/timeperiods.cfg in FC12 for a few examples.
Object type: contact
define contact {
}
contact_name Benvealias Christian Benvenuti
... HOST notificationparameters ...
... SERVICE notificationparameters ...
... addresses ...
... etc ...
Object type: contact
define contact {
}
contact_name Benvealias Christian Benvenuti
... HOST notificationparameters ...
... SERVICE notificationparameters ...
emailpageraddress1address2...address6
... addresses ...
... etc ...
Object type: contact
define contact {
}
contact_name Benvealias Christian Benvenuti
... HOST notificationparameters ...
... SERVICE notificationparameters ...
host_notifications_enabledhost_notification_periodhost_notification_commandshost_notification_options
... addresses ...
... etc ...
Object type: contact
define contact {
}
contact_name Benvealias Christian Benvenuti
... HOST notificationparameters ...
... SERVICE notificationparameters ...
service_notifications_enabledservice_notification_periodservice_notification_commandsservice_notification_options
... addresses ...
... etc ...
Object type: contactdefine contact { contact_name benve alias Christian Benvenuti email benve@univabc.edu.ni
host_notifications_enabled 1 host_notification_period 24x7 host_notification_commands host-notify-by-email host_notification_options d,u,r
service_notifications_enabled 1 service_notification_period 24x7 service_notification_commands notify-by-email service_notification_options w,c,u,r}
Object type: contactgroup
define contact { contact_name admin1 alias Christian Benvenuti email benve@univabc.edu.ni ...}define contact { contact_name admin2 alias Elvis Presley email elvis@univabc.edu.ni ...}define contactgroup { contactgroup_name net_admins alias Administradores de red members admin1, admin2} Another option: contactgroup_members
define hostescalation {
}
define serviceescalation {
}
Escalations (object types)
host_namehostgroup_name
first_notificationlast_notificationnotification_interval
contactscontactgroups
escalation_periodescalation_options
host_namehostgroup_nameservice_description
contactscontactgroups
first_notification last_notificationnotification_interval
escalation_periodescalation_options
Example 1 (1/2)
Internet
net-admin
WWW
www-admin mail-admin
...
10.0.1.100
define serviceescalation {
}
Example 1 (2/2)
host_name WWWservice_description WWW
first_notification 2last_notification 0notification_interval 60
contacts net-admincontactgroups
escalation_period daytimeescalation_options u,d,r
define contact {contact_name www-adminalias Cippa Lippaemail cippa@abc.edu.niservice_notifications_enabled 1service_notification_period 24x7service_notification_commands notify-by-emailservice_notification_options d,u,r...
}define contact {
contact_name net-adminalias Pinco Pallaemail pinco@abc.edu.niservice_notifications_enabled 1service_notification_period 24x7service_notification_commands notify-by-emailservice_notification_options d,u,r...
}
define timeperiod {timeperiod_name daytimealias 8am - 6pmmonday 08:00-18:00tuesday 08:00-18:00wednesday 08:00-18:00thursday 08:00-18:00friday 08:00-18:00saturday 08:00-12:00
}
define host {host_name WWWalias Web Serveraddress 10.0.1.100 ...
}define service {
host_name WWWservice_description WWWcontacts www-admin...
}
Example 2 (1/2)
router1
router2
router3
grp_routers
ENG net
HR net
Internet
ServiceProvider
net-admin-eng
net-admin-hr
grp_it_escalation
define hostescalation {
}
Example 2 (2/2)
host_namehostgroup_name grp_routers
first_notification 4last_notification 0notification_interval 60
contactscontactgroups grp_it_escalation
escalation_periodescalation_options u,d,r
define contact {contact_name net-admin-engalias Christian Benvenutiemail admin@abc.eng.edu.nihost_notifications_enabled 1host_notification_period 24x7host_notification_commands host-notify-by-emailhost_notification_options d,u,r...
}define contact {
contact_name net-admin-hralias Pinco Pallaemail admin@abc.hr.edu.nihost_notifications_enabled 1host_notification_period 24x7host_notification_commands host-notify-by-emailhost_notification_options d,u,r...
}define contactgroup { contactgroup_name grp_it_escalation alias Escalation group members net-admin-eng, net-admin-hr }
define hostgroup { hostgroup_name grp_routers alias All routers members router1, router2, router3}
Parents and Dependencies
● Parents● Host – Host
● Dependencies● Host/s - Host/s● Service/s – Service/s
Is the difference between the following two cases clear?
● Parent (host-host)● Dependencies (host-host)
Parents / Host-HostExample 1
NagiosInternet
WWW(10.0.2.100)
10.0.2.1
10.0.1.110.0.1.2
Mail(10.0.2.101)
Router
define host { host_name WWW alias Web Server address 10.0.2.100 parents Router ...}
define host { host_name Mail alias Mail Server address 10.0.2.101 parents Router ...}
define host { host_name Router alias Main router address 10.0.1.1 ...}
Parents / Host-HostExample 2
Nagios
Internet
WWW(10.0.2.100)
10.0.2.1
10.0.1.1
10.0.1.2
Mail(10.0.2.101)
Router
define host { host_name WWW alias Web Server address 10.0.2.100 parents Router ...}
define host { host_name Mail alias Mail Server address 10.0.2.101 parents Router ...}
define host { host_name Router alias Main router address 10.0.1.1 ...}
?
Parents / Host-HostExample 3
Nagios
Internet
WWW(10.0.2.100)
10.0.2.1
10.0.1.1
Mail(10.0.2.101)
Routerdefine host { host_name WWW alias Web Server address 10.0.2.100 parents Router ...}
define host { host_name Mail alias Mail Server address 10.0.2.101 parents Router ...}
define host { host_name Router alias Main router address 10.0.1.1 ...}
?
Parents / Host-HostExample 4
Nagios
Internet
WWW(10.0.3.100)
10.0.3.1
10.0.2.2
10.0.1.2
Mail(10.0.3.101)
Router1define host { host_name WWW alias Web Server address 10.0.2.100 parents ??? ...}
define host { host_name Mail alias Mail Server address 10.0.2.101 parents ??? ...}
define host { host_name Router alias Main router address 10.0.1.1 ...}
Router2
10.0.2.1
10.0.1.1
Dependencies / Host-Host
● It is not the same as parent-child● This relationship does not depend on the network
topology
Dependencies / Service-ServiceExample 1
NagiosInternet
Mail(10.0.2.100)
10.0.2.1
10.0.1.110.0.1.2
DNS(10.0.2.101)
Router
define host {host_name Mailalias Mail server (SMTP/IMAP)Address 10.0.2.100check_command check-host-alive...
}define service {
host_name Mailservice_description SMTP servercheck_command check_smtp...
}define service {
host_name Mailservice_description IMAP servercheck_command check_imap...
}define host {
host_name DNSalias Primary DNS Serveraddress 10.0.2.101check_command check-host-alive...
}define service {
host_name DNSservice_description Primary DNS servercheck_command check_dns...
}
define servicedependency {host_name DNSservice_description DNS Serverdependent_host_name Maildependent_service_description Mail Server (SMTP/IMAP)execution_failure_criteria c,unotification_failure_criteria c,u
}
Critical, Unknown
Dependencies / Service-ServiceExample 2
Nagios
Internet
Mail(10.0.2.100)
10.0.2.1
10.0.1.1
10.0.2.2
DNS(10.0.2.101)
Router
define host {host_name Mailalias Mail server (SMTP/IMAP)Address 10.0.2.100check_command check-host-alive...
}define service {
host_name Mailservice_description SMTP servercheck_command check_smtp...
}define service {
host_name Mailservice_description IMAP servercheck_command check_imap...
}define host {
host_name DNSalias Primary DNS Serveraddress 10.0.2.101check_command check-host-alive...
}define service {
host_name DNSservice_description Primary DNS servercheck_command check_dns...
}
define servicedependency {host_name DNSservice_description DNS Serverdependent_host_name Maildependent_service_description Mail Server (SMTP/IMAP)execution_failure_criteria c,unotification_failure_criteria c,u
}
?
Dependencies / Service-ServiceExample 3
Nagios
Internet
Mail(10.0.2.100)
10.0.2.1
10.0.1.1
DNS(10.0.2.101)
Router
define host {host_name Mailalias Mail server (SMTP/IMAP)Address 10.0.2.100check_command check-host-alive...
}define service {
host_name Mailservice_description SMTP servercheck_command check_smtp...
}define service {
host_name Mailservice_description IMAP servercheck_command check_imap...
}define host {
host_name DNSalias Primary DNS Serveraddress 10.0.2.101check_command check-host-alive...
}define service {
host_name DNSservice_description Primary DNS servercheck_command check_dns...
}
define servicedependency {host_name DNSservice_description DNS Serverdependent_host_name Maildependent_service_description Mail Server (SMTP/IMAP)execution_failure_criteria c,unotification_failure_criteria c,u
}
?
Dependencies / Service-ServiceExample 4
Nagios
Internet
Mail(10.0.2.100)
10.0.2.1
10.0.1.1
DNS(10.0.2.101)
Router
define host {host_name Mailalias Mail server (SMTP/IMAP)Address 10.0.2.100check_command check-host-alive...
}define service {
host_name Mailservice_description SMTP servercheck_command check_smtp...
}define service {
host_name Mailservice_description IMAP servercheck_command check_imap...
}define host {
host_name DNSalias Primary DNS Serveraddress 10.0.2.101check_command check-host-alive...
}define service {
host_name DNSservice_description Primary DNS servercheck_command check_dns...
}
define servicedependency {host_name DNSservice_description DNS Serverdependent_host_name Maildependent_service_description Mail Server (SMTP/IMAP)execution_failure_criteria c,unotification_failure_criteria c,u
}
?
VPN
Dependencies / Service-Service
What are other examples of dependencies between services?
define hostdependency {
}
define servicedependency {
}
DependenciesHost-Host vs Service-Service
dependent_host_namedependent_hostgroup_name
inherits_parent execution_failure_criteria notification_failure_criteriadependency_period
host_namehostgroup_name
dependent_host_namedependent_hostgroup_namedependent_service_description
inherits_parent execution_failure_criteria notification_failure_criteriadependency_period
host_namehostgroup_nameservice_description
define hostdependency {
}
Dependencies
dependent_host_name = X
inherits_parent execution_failure_criteria notification_failure_criteriadependency_period
host_name = Y
X depends on Y
OR
Y depends on X
???
Check thedocumentation
Templates
● They allow you to write configurations easier to maintain and sanity-check
● Inheritance support● Multiple templates support
Templates(= Object Oriented Configuration)
X = 10Y = 120Z = YesK = 0.1A = 1B = 2
X = 10Y = 120Z = YesK = 0.1A = 3B = 12
X = 10Y = 120Z = YesK = 0.1A = 5B = 7
X = 50Y = 0Z = YesK = 0.1A = 5B = 7
Template T1X = 10Y = 120Z = YesK = 0.1
Use Template T1A = 1B = 2
Use Template T1A = 3B = 12
Use Template T1A = 5B = 7
X = 50Y = 0Z = YesK = 0.1A = 5B = 7
Templates(= Object Oriented Configuration)
X = 10Y = 120Z = YesK = 0.1A = 1B = 2
X = 10Y = 120Z = YesK = 0.1A = 3B = 12
X = 10Y = 120Z = YesK = 0.1A = 5B = 7
X = 50Y = 0Z = YesK = 0.1A = 5B = 7
Template T1X = 10Y = 120
Use Templates T1,T2A = 1B = 2
Use Templates T1,T2A = 3B = 12
Use Templates T1,T2A = 5B = 7
Use Template T2X = 50Y = 0A = 5B = 7
Template T2Z = YesK = 0.1
Templates(= Object Oriented Configuration)
X = 10Y = 120Z = YesK = 0.1A = 1B = 2
X = 10Y = 120Z = YesK = 0.1A = 3B = 12
X = 10Y = 120Z = YesK = 0.1A = 5B = 7
X = 10Y = 120Z = NoK = 0.5A = 5B = 7
Template T1X = 10Y = 120
Use Template T2A = 1B = 2
Use Template T2A = 3B = 12
Use Template T2A = 5B = 7
Use Template T1Z = 10K = 0.5A = 5B = 7
Template T2Use Template T1Z = YesK = 0.1
What if I addX = 11here?
Templates● Special keywords
● register– The parameter passed to the option register is what
distinguishes objects (value 1) from templates (value 0)● use
– Used to list the template/s to use
define host { name WWW1 A = 1 B = 2 C = 5 register 1}
define host { name WWW2 A = 1 B = 2 C = 6}
define host { name WWW-generic A = 1 B = 2 register 0}
define host { use WWW-generic name WWW3 C = 7}
Event Handlers
● Exercise:● Using the online documentation try to understand
what this feature is used for and how to configure it
Active checks vs Passive checks
● Exercise:● Using the online documentation try to understand
what the difference between the two types of checks are (no need to understand the configuration for now, just the functionality)
Active checks vs Passive checks
● Active checks● You configure Nagios to periodically check the status of
hosts/services
● Passive checks● You configure Nagios to accept asynchronous
hosts/services check status information from other applications– Special case: info received from another (or more than one)
Nagios instance
● Active and passive checks are not exclusive● Active checks can be configures to kick-in if no passive
check info is received for a given amount of time
Passive checks
● They make sense mainly when:● the check process/scheme requires a variable and
possibly long time to execute, or● another application already implements the logic
required to determine the status of a host/service and can be configured to return it asynchronously.
Passive checks
...accept_passive_service_checks = 1accept_passive_host_checks = 1
...
FC12: /etc/nagios/nagios.cfg
define host {host_name router_engalias Router Engineering campus...active_checks_enabled 1passive_checks_enabled 1
}
0 00 11 01 1
define service {host_name web_server , ...service_description WEB server...active_checks_enabled 0passive_check_enabled 1
}
All combinationsare valid
Exercise:Check the documentation and find outwhat “Freshness” is with regards topassive checks.
● Exercise● Find the location of the file nagios.cmd and
determine what it is and what it is used for.
# ls /var/spool/nagios/cmd/nagios.cmd -laprw-rw----. 1 nagios nagios 0 2010-02-12 17:20 /var/spool/nagios/cmd/nagios.cmd
# locate nagios.cmdOR# rpm -ql nagios | grep cmdOR...
# file /var/spool/nagios/cmd/nagios.cmd/var/spool/nagios/cmd/nagios.cmd: fifo (named pipe)
(The examples above assume you are using the default installation with FC12)
Nagios Command PIPE
Nagios
process
Filesystem
/
spool
nagios
cmd
nagios.cmd
ApplicationXYZ
NOTE:The PIPE is unidirectional.Is it clear what this means?
Nagios Service Check Acceptor (NSCA)
Nagiosprocess
Filesystem
/
spool
nagios
cmd
nagios.cmd
ncsaserver
ncsaclient
(send_nsca)
ApplicationXYZ
(it could beanother Nagios)
Nagios Service Check Acceptor (NSCA)
ncsaclient
(send_nsca)
(The example assumes you are using the default installation with FC12)
server_port = 5667nsca_user = nagios
command_file = password = decryption_method =
password =encryption_method =
/etc/nagios/nsca.cfg /etc/nagios/send_nsca.cfg
What about theserver port number?
5667
ncsaserver(nsca)
NSCA – Running Options
● OPTIONAL Exercise● By default FC12 installs NSCA as a standalone
service, but you can configure it so that it runs via inetd/xinetd.
● What are the differences between the two alternatives (ie, standalone vs xinetd)?
Web Interface
Web InterfaceWhat could be the problem here?
Web Interface
● Starting/Stopping Nagios● Default account● Adding new users
● Managing passwords● Managing permissions
● Executing commands● How to read the information
How many of youknow how to
configure a web serverlike Apache?
Starting/stopping the server
Configuring permissions
Configuring users/passwords
Log files
Directory aliases
Apache – quick review
● Starting/Stopping the server● service httpd start|stop|status
How many of youknow how to
configure a web serverlike Apache?
Starting/stopping the server
Configuring permissions
Configuring users/passwords
Log files
Directory aliases
Internal Network(10.0.0.0/16)
Apache – quick review● Configuring permissions
● Example “Allow only internal hosts to access it”
Order Deny, Allow
Deny From All
Allow From 10.0.0.0/16
How many of youknow how to
configure a web serverlike Apache?
Starting/stopping the server
Configuring permissions
Configuring users/passwords
Log files
Directory aliases
Nagios(+Apache)
Internet
Where do Iconfigure this?
Apache – quick review● Configuring user/password: htpasswd
● Example that adds the user guest– htpasswd /etc/nagios/passwd guest
How many of youknow how to
configure a web serverlike Apache?
Starting/stopping the server
Configuring permissions
Configuring users/passwords
Log files
Directory aliases
What package doesthis command belongto?
How do I determine whichpasswd file to use?
Does this “user” have toexist in /etc/passwd too?
Apache – quick review● Directory aliases alias /nagios/ /usr/share/nagios/html/ scriptAlias /nagios/cgi-bin/ /usr/lib/nagios/cgi-bin/
How many of youknow how to
configure a web serverlike Apache?
Starting/stopping the server
Configuring permissions
Configuring users/passwords
Log files
Directory aliases
This is configured automatically when youinstall Apache and Nagios via tools like yum (on Fedora).However, when you install Nagios from source code, you must know how to configure the above aliases explicitly.Do you know how to do it?
Apache – quick review● Log files
● /var/log/httpd/...
How many of youknow how to
configure a web serverlike Apache?
Starting/stopping the server
Configuring permissions
Configuring users/passwords
Log files
Directory aliases
Exercise
Nagios Apache
Filesystem
/
Web Interface
● Starting/Stopping Nagios● How do you do (and test) it in Fedora?
● Default account● Adding new users
● Managing passwords● Managing permissions
● Executing commands● How to read the information
Web Interface
● Starting/Stopping Nagios● Default account
● nagiosadmin● What can you do if you can't find/remember the
password?
● Adding new users● Managing passwords● Managing permissions
● Executing commands● How to read the information
Web Interface
● Starting/Stopping Nagios● Default account● Adding new users
● Managing passwords– You configure passwords with the ....................... command.
● Managing permissions
● Executing commands● How to read the information
Web Interface
● Starting/Stopping Nagios● Default account● Adding new users
● Managing passwords● Managing permissions
– Who can access what: Apache config + Nagios config– (NAGIOS: ...)
● Executing commands● How to read the information
Web Interface
● Starting/Stopping Nagios● Default account● Adding new users
● Managing passwords● Managing permissions
● Executing commands● For each contact/user you can specify what objects (hosts/services)
he/she can check.
● With a combination of the object and contact configurations you can specify what commands the contacts can execute on the objects.
● How to read the information
Web Interface
● Starting/Stopping Nagios● Default account● Adding new users
● Managing passwords● Managing permissions
● Executing commands● How to read the information
● The interface is pretty intuitive. Let's play a bit with it ...
This class is based on the
Fedora Core 12 distribution.
Before we start with the labs ...
● You know how to install an application (rpm, yum, ...)
● You know how to determine what configuration files an application uses
● You know how to start and stop a system service● service <service_name> status|start|stop
● You know where to find and how to use log files (syslog, /var/log/....)
● You know how to check the firewall configuration and clear it if necessary.
Right?
Installation and basic configuration (1/2)
● FEDORA: yum install nagios● (in FC12 servono pure tutte le plugins una a una,
vedi p.87 del libro)
● Optional exercise: install it from the tarball● Linux packet management is outside the scope of
this workshop and you are assumed to be able to install applications from the source code. I therefore suggest you trying to install (the very latest version of) Nagios from the tarball.
Installation and basic configuration (2/2/)
● Managing the system service nagios● service nagios <COMMAND>
● What is the main configuration file/directory?● Let's look at the Nagios config file/s together ...
● Organization of the config files for a complex setup
Exercises
.6.5.4
.3 .2 .1
Net 10.0.1.0/24
Net 10.0.3.0/24 Net 10.0.4.0/24
Net 10.0.2.0/24
.1 .2 .3
.4.5.6
.1 .2 .3.1
.6
.3
Net 10.0.5.0/24
.1 .2
.3.4
Internet
eth0
eth1eth1
eth1eth1
eth0
eth0eth0
.5
.2
.5.4 .4.5.6
.6.5.4
.3 .2 .1
Net 10.0.X.0/24
Exercise 1
In each group:●Let's install and configure NAGIOS on the router.●Let's define a host instance for each host in the group.●Let's define a host group that includes all the hosts of the group.
Exercise 2
.6.5.4
.3 .2 .1
Net 10.0.1.0/24
Net 10.0.5.0/24
.1
eth0
eth1
.5
In each group:
● Let's define a host instance for the main router 10.0.5.5 and one for the DNS server/s
● For the DNS server/s let's also define a DNS service.
● Let's define a host group where to include the main router and the DNS server/s.
Any problemhere?
Exercise 3
.6.5.4
.3 .2 .1
Net 10.0.1.0/24
Net 10.0.3.0/24 Net 10.0.4.0/24
Net 10.0.2.0/24
.1
.1.1
Net 10.0.5.0/24
.1 .2
.4.3
eth0
eth1 eth1
eth1eth1
In each group:●Let's define a host instance for each router●Let's define a host group that includes all the routers
.5
Exercise 4
.2 .1
Net 10.0.1.0/24
Net 10.0.3.0/24 Net 10.0.4.0/24
Net 10.0.2.0/24
.1 .2
.1 .2.1
Net 10.0.5.0/24
.1 .2
.3.4
eth0
eth1eth1
eth1eth1
eth0
eth0eth0
.5
.2WEB
WEB WEB
WEB
In each group:●Let's configure the host with address 10.0.x.2 as the group web server●Let's create an host instance for the web server of each group●Let's define a host group that includes all web servers●Let's define the web servers as depending on the associated routers
More exercises here ... if we have time.
Documentacion● http://www.nagios.org●
● + many articles/tutorials freely available
Copyright● This presentation is released under the
Creative Common License:● Attribution, Noncommercial, Share Alike 2.5● (http://creativecommons.org/licenses/by-nc-sa/2.5/)
● Attribution
● You must attribute the work in the manner specified by the author or licensor.
● Noncommercial.
● You may not use this work for commercial purposes.
● Share Alike.
● If you alter, transform, or build upon this work, you may distribute the resulting work only under a license identical to this one.
CCCreativeCommons
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