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Monitoring computer's temperature with lm_sensors

One of the primary reasons I use SSD drives on both of my Mac Minis that I use as hypervisors (besides speed), is that compared to regular hard drives, SSD drives consume far less power and more importantly generate less heat. Before using SSD drives on my machines, the fan noise both of them made during the middle of summer was pretty evident compared to any other time during the year.

Although at the time I did little research about proactively monitoring the temperature of my machines, now thanks to the Nagios book that I'm currently reading, I learned about the tool lm-sensors, which is available to monitor the hardware temperature in Linux.

Installing lm-sersors in Ubuntu Server 12.04 is really simple.

sudo apt-get install libsensors4 libsensors4-dev lm-sensors

Since lm-sensors requires low-level hooks to monitor hardware temperate, it comes with the utility sensors-detect, which can be used to automatically detect and load the appropriate kernel modules for the lm-sensors tool to function on the respective piece of hardware.

[email protected]:~$ sudo sensors-detect
# sensors-detect revision 5984 (2011-07-10 21:22:53 +0200)
# System: Apple Inc. Macmini5,1
# Board: Apple Inc. Mac-8ED6AF5B48C039E1

This program will help you determine which kernel modules you need
to load to use lm_sensors most effectively. It is generally safe
and recommended to accept the default answers to all questions,
unless you know what you're doing.

Some south bridges, CPUs or memory controllers contain embedded sensors.
Do you want to scan for them? This is totally safe. (YES/no): YES
[...]

In the case of my mid 2011 Apple Mac Minis, it was only able to use the coretemp module. File /etc/modules :

# Generated by sensors-detect on Sat Feb  2 21:22:20 2013
# Chip drivers
coretemp

After the module has been added, then its just a matter of loading the recently applied modules.

[....]
Do you want to add these lines automatically to /etc/modules? (yes/NO)yes
Successful!

Monitoring programs won't work until the needed modules are
loaded. You may want to run 'service module-init-tools start'
to load them.

Unloading i2c-dev... OK
Unloading i2c-i801... OK
Unloading cpuid... OK

[email protected]:~$ sudo service module-init-tools start
module-init-tools stop/waiting
[email protected]:~$

Now that the appropiate kernel modules have been loaded. I have everything needed to check the temperature.

[email protected]:~$ sensors
coretemp-isa-0000
Adapter: ISA adapter
Physical id 0: +49.0°C (high = +86.0°C, crit = +100.0°C)
Core 0: +48.0°C (high = +86.0°C, crit = +100.0°C)
Core 1: +50.0°C (high = +86.0°C, crit = +100.0°C)

applesmc-isa-0300
Adapter: ISA adapter
Exhaust : 1801 RPM (min = 1800 RPM)
TA0P: +36.0°C
TA0p: +36.0°C
TA1P: +34.8°C
TA1p: +34.8°C
TC0C: +47.0°C
TC0D: +44.8°C
TC0E: +57.5°C
TC0F: +58.5°C
TC0G: +94.0°C
TC0J: +0.8°C
TC0P: +42.5°C
TC0c: +47.0°C
TC0d: +44.8°C
TC0p: +42.5°C
TC1C: +50.0°C
TC1c: +50.0°C
TCFC: +0.2°C
TCGC: +49.0°C
TCGc: +49.0°C
TCPG: +98.0°C
TCSC: +50.0°C
TCSc: +50.0°C
TCTD: +255.5°C
TCXC: +49.5°C

Of course, I just had to write a Nagios plugin to monitor them:

#!/usr/bin/env perl
use strict;
# Tony Baltazar. root[@]rubyninja.org

use constant OK => 0;
use constant WARNING => 1;
use constant CRITICAL => 2;
use constant UNKNOWN => 3;

my %THRESHOLDS = (OK => 70, WARNING => 75, CRITICAL => 86);

# Sample output
#Physical id 0:  +55.0°C  (high = +86.0°C, crit = +100.0°C)
#Core 0:         +54.0°C  (high = +86.0°C, crit = +100.0°C)
#Core 1:         +55.0°C  (high = +86.0°C, crit = +100.0°C)
my @get_current_heat = split "\n", `sensors 2>/dev/null|grep -E -e '(Physical id 0|Core [0-1])'`;


my $counter = 0;
my $output_string;

for my $heat_usage_per_core (@get_current_heat) {
	$heat_usage_per_core =~ /(.*):\s+\+([0-9]{1,3})/;
	my $core = $1;
	my $temp = $2;
	
	
	if ($temp < $THRESHOLDS{OK}) {
		$output_string .= "$core - temperature : $temp" . 'C | ';
		$counter++;
	} elsif ( ($temp > $THRESHOLDS{OK}) && ($temp >= $THRESHOLDS{WARNING}) && ($temp < $THRESHOLDS{CRITICAL}) ) {
		print "WARNING! $core temperature: $temp\n";
		exit(WARNING);
	} elsif ( ($temp > $THRESHOLDS{OK}) && ($temp > $THRESHOLDS{WARNING}) && ($temp >= $THRESHOLDS{CRITICAL}) ) { 
		print "CRITICAL! $core temperature: $temp\n";
		exit(CRITICAL);
	}
}

if ($counter == 3 ) {
	print $output_string;
	exit(OK);
} else {
	print "Unable to get all CPU's temperature.\n";
	exit(UNKNOWN);
}

Programming: 

Linux: 

Awesome Applications: 

Monitoring DHCP server with check_dhcp

Setting Nagios to monitor my DHCP server using the plugin check_dhcp was a little tricky to setup.

First, the check_dhcp documentation indicates setting setuid on the check_dhcp binary in order to successfully query the dhcp server and receive a valid dhcp offer.

[email protected] libexec]# su - nagios -c '/usr/local/nagios/libexec/check_dhcp -s 192.168.1.2'
Warning: This plugin must be either run as root or setuid root.
To run as root, you can use a tool like sudo.
To set the setuid permissions, use the command:
chmod u+s yourpluginfile
Error: Could not bind socket to interface eth0. Check your privileges...

Fix:

chown root.root check_dhcp
chmod u+s check_dhcp

Secondly, since I always have all of my machines block all incoming traffic, I had to open up the UDP port 68 in order for the Nagios machine to accept the dhcp offer.

iptables -A INPUT -p udp --dport 68 -j ACCEPT

Linux: 

Awesome Applications: 

Custom WordPress auto update via FTP

When I originally migrated my blog off GoDaddy, one of the things that stopped functioning was the WordPress auto update feature. Luckily, I was able to easily overcome this using my own custom FTP settings. For its simplicity, I used vsftpd.

Install:

yum install vsftpd
chkconfig vsftpd on

Configure vsftpd to jail FTP users to their home directory in /etc/vsftpd/vsftpd.conf :

chroot_local_user=YES

Restart vftpd:

/etc/init.d/vsftpd restart

Now, I'll create the user that will be used to download and install the WordPress auto updates. :

useradd -d /PATH/TO/WORDPRESS/SITE -G apache -s /sbin/nologin apache_ftp_user
passwd apache_ftp_user

Before applying an update, update your permissions:

chown -R apache_ftp_user:apache /PATH/TO/WORDPRESS/SITE

Now use apache_ftp_user username and password on the WordPress FTP connection wizard page:

WordPress FTP Connection Information

Awesome Applications: 

Certificate validation issue during Spacewalk install

For some really annoying reason Spacewalk failed to populate the database during the initial setup.
Fix: Make sure your user's database password does not have special characters!

[[email protected] ~]# spacewalk-setup --disconnected --external-db
** Database: Setting up database connection for PostgreSQL backend.
Hostname (leave empty for local)?
Database? dbnamehere
Username? usernamehere
Password?
** Database: Populating database.
The Database has schema. Would you like to clear the database [Y]? Y
** Database: Clearing database.
** Database: Shutting down spacewalk services that may be using DB.
** Database: Services stopped. Clearing DB.
** Database: Re-populating database.
*** Progress: ##################################
* Setting up users and groups.
** GPG: Initializing GPG and importing key.
* Performing initial configuration.
* Activating Spacewalk.
** Loading Spacewalk Certificate.
** Verifying certificate locally.
** Activating Spacewalk.
There was a problem validating the satellite certificate: 1

Databases: 

Linux: 

Awesome Applications: 

OpenBSD: PF firewall for the paranoid

Block all traffic except for ssh.

/etc/pf.conf

tcp_services = "{ 22 }"
block all
pass out on em0 proto tcp to any port $tcp_services keep state
pass in on em0 proto tcp to any port $tcp_services keep state

Enabling rules:

# pfctl -e ; pfctl -f /etc/pf.conf
pfctl: pf already enabled

Awesome Applications: 

Unix: 

Writing custom Nagios plugins: check_public-ip

Now that I think Nagios is the greatest thing since slice bread, I'm slowly but surely re-writing all my custom monitoring scripts to Nagios plugins.

The following is a Nagios plugin ready script that I used to replace my old public IP monitoring (See https://www.rubysecurity.org/ip_monitoring ).

#!/bin/bash

STATE_OK=0
STATE_WARNING=1
STATE_CRITICAL=2
STATE_UNKNOWN=3

current_ip="YOUR-IP-ADDRESS-HERE"
ip=`curl -connect-timeout 30 -s ifconfig.me`

if [ "$current_ip" != "$ip" ] || [ -z "$ip" ]
then
        if [[ "$ip" =~ "Service Unavailable" ]] || [[ "$ip" =~ "html" ]]
        then
                echo "IP service monitoring is unavailable."
                exit $STATE_WARNING
        elif [[ "$ip"  =~ [0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3} ]]
        then
                echo "ALERT: Public IP has changed. NEW IP: $ip"
                exit $STATE_CRITICAL
        else
                echo "Unknown state detected."
                exit $STATE_UNKNOWN
        fi

else
        echo "Public OK: $ip"
        exit $STATE_OK
fi

Programming: 

Awesome Applications: 

Cron monitoring plugin for Nagios

#!/bin/bash
STATE_OK=0
STATE_WARNING=1
STATE_CRITICAL=2
STATE_UNKNOWN=3

CRON_CHECK=`ps aux | grep cron|grep -v grep|awk '{print $NF}'|grep -E -e '^(/usr/sbin/cron|crond)$'|wc -l`

case "${CRON_CHECK}" in
        0)  echo "Crond is not running."; exit ${STATE_CRITICAL}
        ;;
        1)  echo "Crond is running."; exit ${STATE_OK}
        ;;
        *)  echo "More than one crond process detected / crond is in an unknown state."; exit ${STATE_WARNING}
        ;;
esac

Programming: 

Awesome Applications: 

Installing Nagios Remote Plugin Executor in FreeBSD 9.1

This also installs the Nagios plugins in addition of nrpe. Follow the text-based menu install options. The installer will create and configure the nagios user account, and will install the naios and nrpe plugins in /usr/local/libexec/nagios .

cd /usr/ports/net-mgmt/nrpe2
make install clean

Update permissions.

chown -R nagios:nagios /usr/local/libexec/nagios

Create nrpe config file.

cd /usr/local/etc
cp nrpe.cfg-sample nrpe.cfg

Add the following entry to /etc/rc.conf .

nrpe2_enable="YES"

Edit nrpe.cfg (Example: 192.168.1.5 is my nagios server)

allowed_hosts=192.168.1.5

Start the nrpe daemon.

/usr/local/etc/rc.d/nrpe2 start

Awesome Applications: 

Unix: 

Installing Nagios Remote Plugin Executor in Solaris 11

Install gcc

pkg install pkg://sfe/runtime/gcc pkg://sfe/sfe/developer/gcc

Install system headers (not really sure if all listed were necessary):

pkg install SUNWhea SUNWbinutils SUNWarc SUNWgcc SUNWgccruntime SUNWlibsigsegv SUNWgm4 SUNWgnu-automake-110 SUNWaconf

Update your PATH:

PATH=$PATH:/usr/gcc/bin:/usr/sfw/bin:/usr/ccs/bin
export PATH

Manually create nagios user account, home directory, group, and assigned him a password.

mkdir -p /usr/local/nagios
useradd -d /usr/local/nagios -m nagios
groupadd nagios
usermod -G nagios nagios
passwd nagios

Download, extract, compile and install nrpe.

wget http://prdownloads.sourceforge.net/sourceforge/nagios/nrpe-2.13.tar.gz
tar -xvf http://prdownloads.sourceforge.net/sourceforge/nagios/nrpe-2.13.tar.gz
cd /opt/nrpe-2.13
./configure --with-nagios-user=nagios --with-nagios-group=nagios
make install
make install-daemon-config
cp src/check_nrpe /usr/local/nagios/libexec

Update permissions.

chown -R nagios:nagios /usr/local/nagios/

Add the following entry to /etc/services

nrpe 5666/tcp # NRPE

Add the following entry to /etc/inetd.conf

nrpe stream tcp nowait nagios /usr/sbin/tcpd /usr/local/nagios/bin/nrpe -c /usr/local/nagios/etc/nrpe.cfg -i

Convert and add the new legacy inetd entry to SMF.

inetconv
inetconv -e

Awesome Applications: 

Unix: 

Creating large files in Solaris for testing purposes

In the Linux world, I use the dd utility to create files that need to be a certain size. Even though it works perfectly fine, its kind of annoying figuring out the output file's size of the file. This is because the size is based on the "bs" (block size) value and the total number of block size "count" together.

For example, the following dd command creates a 300 mb file called 300mb-test-fil. Each block size will be 1000 bytes, and I want of a total of 300,000 blocks.
Formula: ( (1000 x 300000) / 1000000 )

[[email protected] ~]$ dd if=/dev/zero of=300mb-test-file bs=1000 count=300000
300000+0 records in
300000+0 records out
300000000 bytes (300 MB) copied, 2.0363 s, 147 MB/s

Luckily in the Solaris world this can be easily accomplished using the mkfile utility, without doing any conversion.
I used the mkfile utility to easily create test disk files to experiment with ZFS.

[email protected]:~# mkfile 300m testdisk1
[email protected]:~# mkfile 300m testdisk2
[email protected]:~# ln -s /root/testdisk1 /dev/dsk/testdisk1
[email protected]:~# ln -s /root/testdisk2 /dev/dsk/testdisk2
[email protected]:~# zpool create tonytestpool mirror testdisk1 testdisk2
[email protected]:~# zpool status tonytestpool
pool: tonytestpool
state: ONLINE
scan: none requested
config:

NAME STATE READ WRITE CKSUM
tonytestpool ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
testdisk1 ONLINE 0 0 0
testdisk2 ONLINE 0 0 0

errors: No known data errors

Linux: 

Awesome Applications: 

Unix: 

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