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increase linux file descriptors

increase linux file descriptors

Check Installing CentOS 6.2 on VMware and mounting partitions with noatime posts.

This is very important performance tuning for any web server more information here

#adduser www first http://gadelkareem.com/2012/02/26/adding-new-users-and-admins-to-linux-server/
ulimit -n unlimited - www
#check default number of concurrently open file descriptors 
cat /proc/sys/fs/file-max
#set the number to high value depending on server config
echo '1773914' > /proc/sys/fs/file-max
echo 'fs.file-max=1773914' >> /etc/sysctl.conf
/sbin/sysctl -w fs.file-max=1773914

Mounting partitions with noatime

Check Installing CentOS 6.2 on VMware and increase linux file descriptors posts.

This should help reduce disk IO by telling the system not to update inode access times. more here

vi /etc/fstab
#add noatime to the options of the / file system ex:
/dev/mapper/vg_centos6-lv_root /                       ext4    defaults,noatime         1 1

– remount file system

mount -o remount /
#check
cat /proc/mounts | grep noatime

Change SSH port and enable X11 forwarding

Check Installing CentOS 6.2 on VMware post.

– configure ssh port

cp /etc/ssh/sshd_config /etc/ssh/sshd_config.old
vi /etc/ssh/sshd_config
#uncomment port 22 and change to
port 4568

– enable X11 forwarding

#install needed libraries
yum -y install xorg-x11-xauth xorg-x11-fonts-base liberation-fonts

vi /etc/ssh/sshd_config
#add
X11Forwarding yes
X11DisplayOffset 10
X11UseLocalhost yes

– restart sshd

 /etc/init.d/sshd restart

Now you should connect to 192.168.126.128:4568

Configuring iptables on CentOS

– disable SELINUX

vi /etc/selinux/config
#change
SELINUX=disabled

– reboot or run

 setenforce 0

– add iptables rules

Change server hostname

Check Installing CentOS 6.2 on VMware post.

Adding Hostname to Linux server

vi /etc/hosts
# add
127.0.0.1  localhost.localdomain localhost
192.168.126.128 centos6.vmware.local
vi /etc/sysconfig/network
#change
HOSTNAME=centos6.vmware.local
hostname centos6.vmware.local