Permanent Change of the Time Zone on a Node/Server

First, make a backup of the existing localtime file.

mv /etc/localtime /etc/localtime.bak
Next, create the link:

ln -s /usr/share/zoneinfo/Europe/London /etc/localtime

Now you just need to test your change. Run “date” from the command line, and ensure that the appropriate time, date, and timezone are reported.

The settings will be reverted, if we haven't made the below change.

You need to edit the file /etc/sysconfig/clock and add the entry ZONE="Europe/London" and save the file.

Xen: Create bridge manually with the bond0

ifcfg-eth0

DEVICE=eth0
BOOTPROTO=none
ONBOOT=yes
MASTER=bond0
SLAVE=yes
ISALIAS=no

ifcfg-eth1

DEVICE=eth1
BOOTPROTO=none
ONBOOT=yes
MASTER=bond0
SLAVE=yes
ISALIAS=no

ifcfg-eth1

DEVICE=bond0
BOOTPROTO=none
BONDING_OPTS="mode=1 miimon=100"
ONBOOT=yes
BRIDGE=xenbr0

ifcfg-xenbr0

DEVICE=xenbr0
BOOTPROTO=static
IPADDR=x.x.x.x
NETMASK=x.x.x.x
ONBOOT=yes
TYPE=bridge

vi /etc/xen/xend-config.sxp
Comment out ALL (network-script network-bridge)

service xend restart
service network restart

HDD Health Check Alert

Physical Disk with Smartctl
---------------------------------------

for i in `lshw -class disk -class tape | grep "logical name" | cut -d: -f2`; do echo Disk $i ; echo "=========================================" ;smartctl --all $i | grep 'Status\|Drive' ; echo " "; done > /tmp/output.txt
mail -s "HDD Health Check Alert: `hostname`" user@domain.com  < /tmp/output.txt
rm -f /tmp/output.txt

With MegaRaid Controller

---------------------------------------

for i in `/opt/MegaRAID/MegaCli/MegaCli64 -PDlist -a0|grep Device.Id | awk '{print $3}'` ; do echo Device $i ; smartctl -a -d sat+megaraid,$i /dev/sda|grep 'PASSED\|Reallocated_Sector_Ct\|Temperature_Celsius'; echo " "; done > /tmp/output.txt

mail -s "HDD Health Check Alert: `hostname`" user@domain.com < /tmp/output.txt

rm -f /tmp/output.txt

Commandline fix for the Wordpress DB Connection error

Run the below command from your wordpress installation folder.

for i in `find -iname wp-config.php` ; do j=$(grep 'DB_NAME' $i | awk -F "'" '{print $4}') ; k=$(grep 'DB_USER' $i | awk -F "'" '{print $4}') ;l=$(grep 'DB_PASSWORD' $i | awk -F "'" '{print $4}') ; echo GRANT ALL PRIVILEGES ON $j.* TO $k@"localhost" identified by "'$l'"";" ; done

Script to block IP address which has more connection to the port 80

###This will block the IP which has more than 50 connection to the port 80#####
netstat -anpl | awk '{print $5}'| grep :80 | grep -v [a-z] | cut -d : -f1 | sort -n | uniq -c | sort -n | tail -5 | awk '($1>50){print $2}' > /tmp/iplist.txt
ip_address="<server_IP>"
for i in `cat /tmp/iplist.txt`; do
if [ $i != $ip_address ]
then
iptables -A INPUT -s $i -j DROP
iptables -A FORWARD -s $i -j DROP
netstat -anp | grep $i | awk '{print $7}' | cut -d \/ -f1 | grep -oE "[[:digit:]]{1,}" | xargs kill
fi
done
service iptables save;
rm -f /tmp/iplist.txt