Nagios - Favorite Linux Monitoring Application! by linux journal.

http://www.linuxjournal.com/article/10451

Favorite Linux Monitoring Application

Nagios (51%)

Honorable Mention

Hyperic HQ (15%)

up.time (11%)

Nagios was not only recently dubbed one of the most important open-source apps of all time, but it also is the winner of the new Readers' Choice category, Favorite Linux Monitoring Application. A slim majority 51% of you use Nagios to keep close tabs on your networks of all shapes, sizes and levels of complexity. Most of you not using Nagios opt for the Honorable Mention candidates, Hyperic HQ (with 15%) and up.time (11%). Ganglia and GroundWork also garnered respectable votes in the single digits.

Easy remote syslog-ng setup

This is on CentOS, of course you already have regular syslog installed so download syslog-ng rpm from wherever and install...

Force its install via:

sudo rpm --force -Uvh syslog-ng-1.6.12-1.el5.centos.i386.rpm

or remove the old syslog first via:

rpm -e --nodeps rsyslog

stop syslog and start syslog-ng:

sudo /etc/init.d/syslog stop && sudo /etc/init.d/syslog-ng start

Test that its working via:

logger "test message" && sudo tail /var/log/messages

remove syslog from starting and setup syslog-ng to start up on boot:

sudo chkconfig syslog off && sudo chkconfig syslog-ng on && sudo chkconfig --list | grep syslog

Enable remote syslogging on the host syslog server
HOST:
sudo vi /etc/syslog-ng/syslog-ng.conf
add:

source s_network {
tcp(max-connections(5000));
udp();
};

destination d_network {
file ("/var/log/syslog-ng/$HOST/$FACILITY.log");
};

log { source(s_network);
destination(d_network);
};

Sending messages from your syslog-ng client
CLIENT:
sudo vi /etc/syslog-ng/syslog-ng.conf

destination loghost {
tcp("192.168.1.5");
};

log {
source(s_sys);
destination(loghost);
};

Add an iptables allow rule for port 514, and optionally add the -s and mention the host (much more secure)
sudo vi /etc/sysconfig/iptables
add:
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 514 -s 192.168.1.5 -j ACCEPT
restart iptables:
sudo /etc/init.d/iptables restart

Test that its working by running on the client:
logger "test to remote"

and running on the host:
tail -f /var/log/messages

If you see the msg its working .. if not, you fail... try again.

Amazon New features! Loan balancing and monitoring.... finally!

Dear AWS Community Member,

You signed up to be notified when we released monitoring, auto scaling and load balancing for Amazon EC2. We are excited to announce the public beta of these new features: Amazon CloudWatch, a web service for monitoring AWS cloud resources, Auto Scaling for automatically growing and shrinking Amazon EC2 capacity based on demand, and Elastic Load Balancing for distributing incoming traffic across Amazon EC2 compute instances. Together, these capabilities provide you with visibility into the health and usage of your AWS compute resources, enhance application performance, and lower costs.

Monitoring

Amazon CloudWatch is a web service that provides monitoring for AWS cloud resources, starting with Amazon EC2. It provides customers with visibility into resource utilization, operational performance, and overall demand patterns -- including metrics such as CPU utilization, disk reads and writes, and network traffic. To use Amazon CloudWatch, simply select the Amazon EC2 instances that you'd like to monitor; within minutes, Amazon CloudWatch will begin aggregating and storing monitoring data that can be accessed using web service APIs or Command Line Tools.

Auto Scaling

Auto Scaling allows you to automatically scale your Amazon EC2 capacity up or down according to conditions you define. With Auto Scaling, you can ensure that the number of Amazon EC2 instances you're using scales up seamlessly during demand spikes to maintain performance, and scales down automatically during demand lulls to minimize costs. Auto Scaling is particularly well suited for applications that experience hourly, daily, or weekly variability in usage. Auto Scaling is enabled by Amazon CloudWatch and available at no additional charge beyond Amazon CloudWatch fees.

Elastic Load Balancing

Elastic Load Balancing automatically distributes incoming application traffic across multiple Amazon EC2 instances. It enables you to achieve even greater fault tolerance in your applications, seamlessly providing the amount of load balancing capacity needed in response to incoming application traffic. Elastic Load Balancing detects unhealthy instances within a pool and automatically reroutes traffic to healthy instances until the unhealthy instances have been restored. Customers can enable Elastic Load Balancing within a single Availability Zone or across multiple zones for even more consistent application performance.

Like all Amazon Web Services and features, Amazon CloudWatch and Elastic Load Balancing are available on a pay-as-you-go basis with no up-front fee, minimum spend or long term commitment. Auto Scaling is free to Amazon CloudWatch customers. Each instance launched by Auto Scaling is automatically enabled for monitoring and the Amazon CloudWatch monitoring charge will be applied.

For more information on these new features and details on how to start using them, please see the resources listed below:

Amazon EC2 Detail Page

Release Notes

These have been among the most requested Amazon EC2 features by our customers. We hope they prove useful to you, and we look forward to your feedback.

Sincerely,

The Amazon Web Services Team

Amazon has a new feature, reserved instances.

Basically you pay a one time up front fee, and it drastically lowers your hourly $ cost per instance.

You can have a small instance (Small Instance (Default) 1.7 GB of memory, 1 EC2 Compute Unit (1 virtual core with 1 EC2 Compute Unit), 160 GB of instance storage, 32-bit platform)

For around - 65$/month - 780$/year, you could have a dedicated server ... pretty sweet deal.

Now if you add in the reserved instance's feature...

A small instance will cost
$325(reserved instance fee) + $262/year = $587/year ... even better deal.

Sign up for 3 years, and you now are paying...
$587 1st year, and then $262 ... end of 3 years total = $1111 compared to $2340 for the regular price for 3 years.

Rebundeling a running ec2 instance....

ec2-bundle-vol --prefix what_you_want_to_name_it -d /mnt/ami -c pathtocert.pem -k pathtokeyfile.pem -u 123456789 -s 10240 --kernel aki-9b00e5f2 -r i386

-d, --destination PATH
-c, --cert PATH
-k, --privatekey PATH
--kernel ID Id of the default kernel to launch the AMI with.
-r, --arch ARCHITECTURE Specify target architecture. One of ["i386", "x86_64"]
-s, --size MB The size, in MB (1024 * 1024 bytes), of the image file to create. The maximum size is 10240 MB.

(change the kernel type and arch to suite your needs... might as well use the largest size 10240)

This will bundle your running instance, and place the files in /mnt/ami

ec2-upload-bundle -b bucketname -m /mnt/ami/what_you_named_it.manifest.xml --access-key XYZ --secret-key XYZ

This will upload your bundled image to your bucket.

ec2-register /bucket/what_you_named_it.manifest.xml

The last step is to register your image, you will get back the AMI ID, and can either start your instance on the cmd line, or simply login to the web console and start it.

Nagios - Instead of a ping check to see if a host is alive, use http instead

Sometimes (often) ICMP is blocked, so you can't ping check your hosts to see if they are alive.

You can add this to commands.cfg and hosts.cfg for those hosts to check via http instead.

commands.cfg

define command {
   command_name check-host-alive-by-http
   command_line $USER1$/check_http -H $HOSTADDRESS
}

hosts.cfg

define host{
host_name hostname.com
address ip.address
alias hostnamealias
use networking_machines_template
check_command check-host-alive-by-http
}

Installing Nagios

Installing Nagios
---------------------
*need to have basic centos install, with apache installed.



Install rpmforge repo

wget http://apt.sw.be/redhat/el5/en/i386/RPMS.dag/rpmforge-release-0.3.6-1.el5.rf.i386.rpm
wget http://apt.sw.be/redhat/el5/en/x86_64/RPMS.dag/rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm
rpm --import http://dag.wieers.com/rpm/packages/RPM-GPG-KEY.dag.txt
rpm -K rpmforge-release-0.3.6-1.el5.rf.*.rpm #verify package
rpm -i rpmforge-release-0.3.6-1.el5.rf.*.rpm #install package

Install yum-priorities #this is't required, but I like to limit the rpmforge repository from effecting any base packages

yum install yum-priorities
#Make sure that yum-priorities is enabled by editing the /etc/yum/pluginconf.d/priorities.conf
#Edit the .repo files in /etc/yum.repos.d/ and set up priorities by adding the line: (lower number = higher priority, 0 = disabled)
priority=N


Install nagios packages

sudo yum install nagios nagios-devel nagios-plugins nagios-plugins-setuid rrdtool


Configure Nagios

sudo htpasswd -c /etc/nagios/htpasswd.users kylec #Create htpasswd file for auth
sudo htpasswd /etc/nagios/htpasswd.users username #for adding users

sudo vi /etc/nagios/nagios.cfg
comment out...
#cfg_file=/etc/nagios/objects/templates.cfg
#cfg_file=/etc/nagios/objects/localhost.cfg
add...
cfg_file=/etc/nagios/objects/hosts.cfg
cfg_file=/etc/nagios/objects/hostgroups.cfg
cfg_file=/etc/nagios/objects/services.cfg
cfg_file=/etc/nagios/objects/contactgroups.cfg
set...
process_performance_data=1
host_perfdata_command=process-host-perfdata
service_perfdata_command=process-service-perfdata


sudo vi /etc/nagios/cgi.cfg
set...
authorized_for_system_information=*
authorized_for_configuration_information=*
authorized_for_system_commands=*
authorized_for_all_services=*
authorized_for_all_hosts=*
authorized_for_all_service_commands=*
authorized_for_all_host_commands=*


----------------------------------------------------------------------------------------------
Installing Nagios pnp

wget http://switch.dl.sourceforge.net/sourceforge/pnp4nagios/pnp-0.4.13.tar.gz
./configure
make all
make fullinstall

edit hosts.cfg

add:

define host{
use generic-host,host-pnp #add host-pnp to networking_machines_template


define host {
name host-pnp
register 0
action_url /nagios/pnp/index.php?host=$HOSTNAME$' onmouseover="get_g('$HOSTNAME$','_HOST_')" onmouseout="clear_g()"

}

edit services.cfg

Add to the main template... (in my case basic-service)

define service{
use generic-service,srv-pnp (srv-pnp is whats added)
name basic-service
.... truncated


define service {
name srv-pnp
register 0
action_url /nagios/pnp/index.php?host=$HOSTNAME$&srv=$SERVICEDESC$' onmouseover="get_g('$HOSTNAME$','$SERVICEDESC$')" onmouseout="clear_g()"

}

edit commands.cfg

add:

define command {
command_name process-service-perfdata
command_line /usr/bin/perl /usr/local/nagios/libexec/process_perfdata.pl
}

define command {
command_name process-host-perfdata
command_line /usr/bin/perl /usr/local/nagios/libexec/process_perfdata.pl -d HOSTPERFDATA
}

comment out the existing SAMPLE PERFORMANCE DATA COMMANDS

setup configs

cd /usr/local/nagios/etc/pnp/
sudo mv npcd.cfg-sample npcd.cfg
sudo mv process_perfdata.cfg-sample process_perfdata.cfg
sudo mv rra.cfg-sample rra.cfg


If you are seeing ... "File does not exist: /usr/share/nagios/pnp," in your httpd logs.
cp -R /usr/local/nagios/share/pnp/ /usr/share/nagios/pnp

edit as you would like them.

start npcd
/etc/init.d/npcd start
-------------------------------------------------------------------------------------------------------




EXAMPLE .cfgs #this is custom, these are just some examples to get you started.

contacts.cfg

define contact{
contact_name kyle
alias kyle
service_notification_period 24x7
host_notification_period 24x7
service_notification_options w,u,c,r
host_notification_options d,u,r
service_notification_commands notify-by-email
host_notification_commands host-notify-by-email
email kyle@email.com
}

contactgroups.cfg

define contactgroup{
contactgroup_name admins
alias admins
members internal_infosec, kylepager
}


hosts.cfg

define host{
host_name website.com
address website.com
alias website.com
use networking_machines_template
}


hostgroups.cfg

define hostgroup{
hostgroup_name webservers
alias webservers
members server1, server2, server3, website.com
}

services.cfg

define service{
use basic-service
hostgroup_name webservers
service_description HTTP
check_command check_http!
contact_groups admins
}