There are a lot of people do not know what these variables and how they can be used , this Variables exist in php.ini file , the php.ini file is contains settings PHP on server , and for each variable in the php.ini file have a special role and can be disabled and activated with ON and Off

Disable = Off

Activate = On

So now I will explain to you the benefit of each function and put you a choice in the activation and disable

expose_php

Is a a property from which to see PHP version on the server so disabling means not making available to the hacker to know the version of PHP

allow_url_fopen

When you disable this function no one will be able to contain another link in a specific page , but some scripts like AM4SS – Vbulletin need this function for the arrival of notifications within the Admin Control Panel

register_globals

When you Desable this function become possible to control the content of php files difficult and does not allow the Edited only by the owner
So now we come to the disabled and activation of these properties

Enter in the shell and modify the php.ini file with the following command

nano /usr/local/lib/php.ini

By pressing Ctrl + W will open new box writes what you want to search for inside file

Looking for the variable you want edited for example

allow_url_fopen

You’ll find as follows :

allow_url_fopen = On

Mark value after the mark (=) On for activate Off  for disabled , Apply it with the rest of the properties , After completion of the amendment to click on the keys CTRL + X + Y then Enter button

You will see a new command line in the main interface in shell
Observation : you must restart Apache after any amendment to this file for edited is defined in the php and Apache
To restart apache :

service httpd restart

Or you can restart apache using server Control Panel WHM In a private box to restart services From there you can restart any service you want to.

The post What is the role of this variables in php.ini file (expose_php – allow_url_fopen – register_globals) ? appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

I run CentOS on my server, and I often find that my server is being attacked by other computers. Brute force SSH attacks, port scanning, viruses scanning for the ability to spread, things like that. In this article, I’ll show you how to block an IP address on Linux server using IPTables.

The First, I’ll assume you are already using iptables. If you need help setting that up, read this article.

How do I block an IP address ?

Example I want to block incoming request from IP 1.2.3.4, login as root and type the following command

# iptables -I INPUT -s 1.2.3.4 -j DROP

Where,
– I: Inserts the chain at the top of the rules.
– s: Match source IP address.
– j: Jump to the specified target chain when the packet matches the current rule.

To drop packets coming in on interface eth0 from 1.2.3.4, type the following command

# iptables -I INPUT -i eth0 -s 1.2.3.4 -j DROP

How do I block a subnet ?

Use the following syntax to block 10.0.0.0/8

# iptables -I INPUT -s 10.0.0.0/8 -j DROP

How do I save blocked IP address ?

To save blocked IP address to iptables config file, type the following command

# service iptables save

Or

# /etc/init.d/iptables save

How Do I Unblock An IP Address?

First, you need to display blocked IP address along with line number and other information, type the following command

# iptables -L INPUT -n --line-numbers
# iptables -L INPUT -n --line-numbers | grep 1.2.3.4

Sample outputs:

Chain INPUT (policy DROP)
num  target     prot opt source               destination
1    DROP       all  --  1.2.3.4              0.0.0.0/0
2    LOCALINPUT  all  --  0.0.0.0/0            0.0.0.0/0
3    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0
4    ACCEPT     udp  --  203.162.4.1          0.0.0.0/0           udp spts:1024:65535 dpt:53

To unblock 1.2.3.4 you must delete line number 1, enter:

# iptables -D INPUT 1

The post How Do I Block An IP Address On Linux Server ? appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

shutdown command brings the system down in a secure way. All logged-in users are notified that the system is going down, and login is blocked. It is possible to shut the system down immediately or after a specified delay. All processes are first notified that the system is going down by the signal SIGTERM. This gives programs like vi the time to save the file being edited, mail and news processing programs a chance to exit cleanly, etc. shutdown does its job by signalling the init process, asking it to change the runlevel. Runlevel 0 is used to halt the system, runlevel 6 is used to reboot the system, and runlevel 1 is used to put to system into a state where administrative tasks can be performed; this is the default if neither the -h or -r flag is given to shutdown. To see which actions are taken on halt or reboot see the appropriate entries for these runlevels in the file /etc/inittab.(http://linux.about.com/od/commands/l/blcmdl8_shutdow.htm)

Shutdown the machine immediately

Type the following command as root

# shutdown -h now

Shutdown the machine with user defined message

# shutdown -h now 'Server is going down for replace old hardware'

Scheduling the shutdown

Example, schedule shutdown for 3 AM.

# shutdown -h 03:00

Schedule shutdown the system in 5 minutes

# shutdown -h +5

Reboot the machine immediately

# shutdowm -r now

Cancel a running shutdown

# shutdown -c

The post Linux Shutdown Command appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

To disable the reboot action taken by pressing the Ctrl+Alt+Delete key combination, comment out the following line in the file /etc/init/control-alt-delete.conf.

Type the following command

# sudo vi /etc/init/control-alt-delete.conf

Output

# control-alt-delete - emergency keypress handling
#
# This task is run whenever the Control-Alt-Delete key combination is
# pressed, and performs a safe reboot of the machine.

description     "emergency keypress handling"
author          "Scott James Remnant "

start on control-alt-delete

task
exec shutdown -r now "Control-Alt-Delete pressed"

Change the following line

exec shutdown -r now "Control-Alt-Delete pressed"

To

#exec shutdown -r now "Control-Alt-Delete pressed"

Save and exit the file

The post How To Disable Ctrl + Alt + Del On Ubuntu 11 appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

To disable CTRL+ALT+DEL key is configured to use /etc/inittab file. Login as root and edit /etc/inittab file and remove ctrlaltdel entry.
Type the following command

# vi /etc/inittab

Find lines that read as follows

# Trap CTRL-ALT-DELETE
ca::ctrlaltdel:/sbin/shutdown -t3 -r now

Delete or comment out line by prefixing “#”

# Trap CTRL-ALT-DELETE
#ca::ctrlaltdel:/sbin/shutdown -t3 -r now

Save and close the file. Type command to reload /etc/inittab

# init q

The post How To Disable Ctrl + Alt + Del On Centos / RedHat appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

Save Iptables rules

Rules created with the iptables command are stored in memory. If the system is restarted before saving the iptables rule set, all rules are lost. To save netfilter rules, type the following command as root:

# /etc/init.d/iptables save 

If you are using IPv6, enter:

# /etc/init.d/ip6tables save 

The above commands will write the current iptables configuration to /etc/sysconfig/iptables. The next time the system boots, the iptables init script reapplies the rules saved in /etc/sysconfig/iptables. You can also save the iptables rules to a separate file for distribution, backup or other purposes. Type the following command as root

# iptables-save > /root/iptables.rules

If you are using IPv6, enter:

# ip6tables-save  > /root/iptables.rules

Restore Iptables rules

To restore it use the command iptables-restore, type the following command as root:

# iptables-restore < /root/iptables.rules

If you are using IPv6, enter:

# ip6tables-restore < /root/iptables.rules

The post How To Save/Restore Iptables Rules appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.