1. Nagios – Our Open Source Network Management Solution
Presenter: Ling Zhang
LBLnet Services Group
Information Technologies and Services Division
LBNL

2. Contributors Nagios software design and development:
Ethan Galstad (
System integration, configuration, testing:
Ling Zhang, Greg Bell, Harper Mann,
Cedric Hui, Clark Wood, Mike Bennett
18 September 2018
ITSD/LBNL

3. Goals for this talk To explain: To discuss
LBLnet’s point of view of Network Management System
network monitoring problems we encountered
the design of our Nagios network monitoring system
To discuss
the benefits of the nagios system
our future development goals
18 September 2018
ITSD/LBNL

4. Our point of view of a NMS
Proactive network management
Alarm Panel
Connectivity
Performance
Fault isolation
Trend Analysis
Capacity planning
The Notification
Precise
Fast
18 September 2018
ITSD/LBNL

5. Background Information
Network Monitoring tools we have tested and/or used before:
Sun Net Manager
Spectrum
Whatsup Gold
Netmon
SNMPc
Ipmonitor
HP Openview
OpenNMS
InCharge
Home grown scripts
MRTG/RRDtool
etc.
18 September 2018
ITSD/LBNL

6. Background Information
Our fair share of problems with NMS:
Notification storm
65 notifications were received during a router up/down
event. The router has 20 active interface and 32
downstream monitored devices
False alarms
Integration with existing systems (MRTG, Trouble ticket system)
Tech support
our longest outstanding tickets: 2 years and counting
Budget
18 September 2018
ITSD/LBNL

7. In Search of a Better NMS
Accurate and efficient fault detection
Good performance
Extensible
Can be integrated with our existing system
Low maintenance
Fits our budget
18 September 2018
ITSD/LBNL

8. Features of Nagios Open source system runs on most Unix system
Highly extensible
Reliable dependency monitoring
Excellent service monitoring capabilities
Ability to schedule maintenance periods
Flexible notification
18 September 2018
ITSD/LBNL

9. Our Nagios Topology
LBLnet NMS diagram
18 September 2018
ITSD/LBNL

10. Nagios Extensibility Plugins Event handlers External commands
18 September 2018
ITSD/LBNL

11. Nagios Extensibility - Plugins
Compiled executables or scripts (Perl, shell, etc.)
Run by nagios process
Checks device or service status
Example:
define host {
host_name switch1
address
check_command ping_switch }
define service {
host_name switch1
Service_description CPU Util
check_command get_cpu_util
18 September 2018
ITSD/LBNL

12. Services Monitored by Nagios
Nagios uses plugins to check service status
DHCP
DNS
FTP
HTTP
HTTPS
IMAP
NTP
Radius
SMTP
SQL
TFTP
WINS
etc.
18 September 2018
ITSD/LBNL

13. Nagios Extensibility – Event Handelers
Compiled executables or scripts
Run by nagios process
Triggered by host or service status change
Example:
define service{
host_name somehost service_description HTTP max_check_attempts 4
check_command check_http
event_handler restart-httpd
...other service variables... }
18 September 2018
ITSD/LBNL

14. Nagios Extensibility – External Commands
A predefined set of commands issued externally to control the behavior of nagios
Controls notification, monitor scheduling, program start/stop
Issued by external applications (CGI, snmptrapd, etc.)
Reads in by nagios core process during run time
Example
User disabled monitoring of switch1 from web interface
CGI wrote command “disable monitor switch1” to command file
Nagios process read this command and stopped scheduling monitoring for switch1
18 September 2018
ITSD/LBNL

15. Monitoring Network Devices
Ping
Measures system responsiveness via average RTT
SNMP get
CPU
Temperature
Interface/port status
System up time
Power supply status
Throughput
Packet discard rate
etc.
SNMP trap
18 September 2018
ITSD/LBNL

16. Nagios Trap handling Requires Net-SNMP or other trap receiver daemon
Trap receiver notifies nagios about traps received via External Commands
Nagios calls event handlers and/or notifies user
18 September 2018
ITSD/LBNL

17. Dependency Configuration
define host {
use switch-tmpl
host_name switch1
address
parents router1 }
host_name switch2
address
parents switch1
host_name switch3
address
host_name switch4
address
parents switch2
Diagram
18 September 2018
ITSD/LBNL

18. Nagios Notification Similar to event handlers
Triggered by host/service status change
Calls third party notification tools (sendmail, qpage, etc.)
Supports , page, instant messaging etc.
18 September 2018
ITSD/LBNL

19. Nagios Notification format
Subject: switch3 ( ) DOWN
Host: switch3
Address:
Date/Time: Thu Jul 15 14:03:37 PDT 2004
Additional Info: (No Information Returned From Host Check)
Page
DOWN switch3( )
18 September 2018
ITSD/LBNL

20. Maintenance Scheduling
Schedule a maintenance window via Nagios web interface
Uses external commands
Fixed window
Float window
Dependency aware
18 September 2018
ITSD/LBNL

21. Monitoring Subnet with Redundant Network Connections
Solution:
Monitor interface up/down status via Ping
Monitor HSRP status via HSRP mib
Challenge:
Monitoring interface status
Monitoring standby status at the same time
18 September 2018
ITSD/LBNL

22. Performance of Nagios False alarms Notification delay False positive
False negative
Unnecessary
Notification delay
Before: 303 sec
After: 221 sec
18 September 2018
ITSD/LBNL

23. Money and Time Saved Software package cost
InCharge ($$$)
IPmonitor ( $1500)
Nagios ($0)
Software maintenance contract cost
InCharge (>$15,000)
IPmonitor ($500)
Time saved from less unnecessary alarms (Compared to IPmontior)
20 man.hrs/month
18 September 2018
ITSD/LBNL

24. Future development of Nagios
Performance Monitoring
Network element out of resources
Interface buffer drops
Duplex mismatch
Has to be done by inference
Assume heterogeneous network equipment
No use of host SNMP
Derive from combination of interface error types and rates
Integrating with other NMS elements
Syslog
MRTG/RRDtool
Trouble ticket System
Database
Topology discovery
18 September 2018
ITSD/LBNL

25. Conclusion Nagios fits our Network Management needs because:
Accurate and efficient fault detection
Extensibility
Can be easily integrated with our existing system
Low maintenance
Fits our budget
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18 September 2018
ITSD/LBNL

26. Thanks! We are happy to share Questions / comments
send to
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18 September 2018
ITSD/LBNL