GiuseppeTurri Email:g.turri@giuseppeturri.it

Pagina 1 di 3

HOW TO Install Nagios Core on RedHat Enterprise Linux Systems...... Without Problems :-)

1- Install system software needed by nagios installation Webegininstallingandverifyingthepackagerequirementsandso,asrootuser,submitthefollowingcommand: yum install -y wget httpd php gcc glibc glibc-common gd gd-devel make net-snmp

2- Download Nagios core and main plugin WhenI'mwritingthisdocumentthelatestavailableversionofnagioscoreisthe3.4.1andyoucandownloaditbrowsingattheurlhttp://prdownloads.sourceforge.net/sourceforge/nagios/nagios3.4.1.tar.gzordirectlybywgetwiththiscommand: cd /tmp wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.4.1.tar.gz wget http://sourceforge.net/projects/nagiosplug/files/nagiosplug/1.4.15/nagios-plugins-1.4.15.tar.gz Note:ifyoursystemisbehindaproxyserveryoumayneedtoconfiguretheproxytoallowtheinternetconnectiontowgetfollowingthesesteps

addyourproxyto/erc/wgetrcconfigurationfile(uncommentandmodifythetypeofproxyusedinyournetwork) uncommenttheuse_proxy=onsettingor,ifyoudon'twanttousetheproxyatallyoumayturnoffthissettingandissue

thewgetcommandfollowebbyproxy=onproxyuser=userproxypassword=passwordandthentheurl(examplewgetproxy=onproxyuser=userproxypassword=passwordhttp://www.xxx.zzz)

3- Installing Nagios core & main plugin OnceDownloadedthetarfilewehavetocreatetheuserandgroupfornagiosandsosubmitthesecommands:

useradd nagios groupadd nagcmd usermod -a -G nagcmd nagios

Nowwecanextractthesoftwarefromthetarball tar zxf nagios-3.4.1.tar.gz tar zxf nagios-plugins-1.4.15.tar.gz

GiuseppeTurri Email:g.turri@giuseppeturri.it

Pagina 2 di 3

Andinstallthecorenagiossoftware cd nagios ./configure --with-command-group=nagcmd make all make install make install-init make install-config make install-commandmode make install-webconf

andthemainplugin cd ../nagios-plugin* ./configure --with-nagios-user=nagios --with-nagios-group=nagios make make install

cp -R contrib/eventhandlers/ /usr/local/nagios/libexec/ chown -R nagios:nagios /usr/local/nagios/libexec/eventhandlers

Wecanstartthenagionandhttpdservicesbyissuingthecommand service httpd start service nagios start

Terminatedtheinstallationcommandwecansetthesystemtostartupnagiosandhttpdatstartuptime: chkconfig nagios --level 35 on chkconfig httpd --level 35 on

Nowwehavetocreateanusertoaccesstothenagioswebinterfacesowecreateanusernamednagiosadmindefiningapasswordforit: htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin Atthispointthenagioscoreisinstalled,upandrunning.Youcanaccesstoyournagiosinstallationbybrowsingtheurlhttp://yourservername/nagiosYou'llbepromptabasicauthenticationwhereyouhavetousethenagiosadminaccountcreatedwiththelatestcommandsubmitted.Everytimeyoumodifyanagiosconfigurationfileyoumayverifytheconfigurationbythecommand

/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg and,ifallisok,youcanrestartthenagiosservicetoexecutethemodifiedcode.Thenextchapteroftheguideisforhelpingyouincaseofproblems.ToverifyifyourinstallationisfreeofproblemsandtocheckthestatusofyourinstallationIsuggestyouto:

Tryanaccessthroughthewebinterface Trytoaccesstotheservicessectionandtrytorescheduleachecknow Trytoverifythemailnotification(changetheemailaddressinthe

/usr/local/nagios/etc/objects/contacts.cfgconfigurationfile).

GiuseppeTurri Email:g.turri@giuseppeturri.it

Pagina 3 di 3

4- MOST COMMON PROBLEMS RESOLUTION Error403Forbiddenyoudon'thavepermissiontoaccess/nagios/onthisserver.

whenyoutrytoaccessthenagioswebinterfaceChecktheinstallationofthephpsoftwareonyoursystemyum install php service httpd restart

Error:Couldnotopencommandfile/var/nagios/rw/nagios.cmdforupdate!Whenyoutrytorescheduleacheckofaservicebynagioswebinterface chown nagios.nagcmd /usr/local/nagios/var/rw chmod g+rwx /usr/local/nagios/var/rw chmod g+s /usr/local/nagios/var/rw usermod -G nagcmd apache service httpd restart service nagios restart

Youdon'treceiveanyemailnotificationand/oryouareabletosendemailnotificationbycommandline

I'vespentalotoftimewhitthiskindofproblem.... Socheckifyouareabletosendemailbyterminallineasrootuserwiththiscommand:

/usr/bin/printf "Notification Test" | /bin/mail -s "This is a test" your-email@address

Ifyoucanexecutethecommandandyoureceivetheemailnowwecantrytosubmitthesame commandasnagiosusersoexecute:

su - nagios /usr/bin/printf "Notification Test" | /bin/mail -s "This is a test" your-

email@address Probablyyou'llgetthiserror WARNING:RunAsUserforMSPignored,checkgroupids(egid=503,want=51) cannotchdir(/var/spool/clientmqueue/):Permissiondenied Programmoderequiresspecialprivileges,e.g.,rootorTrustedUser. Ifyouhaveasimilarerrormessagewecansolveitbyissuing,asrootuser,thiscommand:

chmod 2755 /usr/sbin/sendmail.sendmail service sendmail restart

Go to NAGIOS website http://www.nagios.com/#ref=s57X3l