Install NetBeans IDE 8.0 on Ubuntu 13.10, 14.04 – Sysads Gazette

original source :

About LAMP

LAMP stack is a group of open source software used to get web servers
up and running. The acronym stands for Linux, Apache, MySQL, and PHP.
Since the virtual private server is already running Ubuntu, the linux
part is taken care of. Here is how to install the rest.

Set Up

The  steps in this tutorial require the user to have root privileges on your VPS. You can see how to set that up in the Initial Server Setup in steps 3 and 4.

Step One—Install Apache

Apache is a free open source software which runs over 50% of the world’s web servers.

To install apache, open terminal and type in these commands:

sudo apt-get update
sudo apt-get install apache2

That’s it. To check if Apache is installed, direct your browser to
your server’s IP address (eg. The page should
display the words “It works!“ like this.

How to Find your Server’s IP address

You can run the following command to reveal your server’s IP address.

ifconfig eth0 | grep inet | awk '{ print $2 }'

Step Two—Install MySQL

MySQL is a powerful database management system used for organizing and retrieving data

To install MySQL, open terminal and type in these commands:

sudo apt-get install mysql-server libapache2-mod-auth-mysql php5-mysql

During the installation, MySQL will ask you to set a root password.
If you miss the chance to set the password while the program is
installing, it is very easy to set the password later from within the
MySQL shell.

Once you have installed MySQL, we should activate it with this command:

sudo mysql_install_db

Finish up by running the MySQL set up script:

sudo /usr/bin/mysql_secure_installation

The prompt will ask you for your current root password.

Type it in.

OK, successfully used password, moving on…

Then the prompt will ask you if you want to change the root password. Go ahead and choose N and move on to the next steps.

It’s easiest just to say Yes to all the options. At the end, MySQL will reload and implement the new changes.

By default, a MySQL installation has an anonymous user, allowing anyone
to log into MySQL without having to have a user account created for
them.  This is intended only for testing, and to make the installation
go a bit smoother.  You should remove them before moving into a
production environment.

Remove anonymous users? [Y/n] y                                            
 ... Success!

Normally, root should only be allowed to connect from 'localhost'.  This
ensures that someone cannot guess at the root password from the network.

Disallow root login remotely? [Y/n] y
... Success!

By default, MySQL comes with a database named 'test' that anyone can
access.  This is also intended only for testing, and should be removed
before moving into a production environment.

Remove test database and access to it? [Y/n] y
 - Dropping test database...
 ... Success!
 - Removing privileges on test database...
 ... Success!

Reloading the privilege tables will ensure that all changes made so far
will take effect immediately.

Reload privilege tables now? [Y/n] y
 ... Success!

Cleaning up...

Once you’re done with that you can finish up by installing PHP.

Step Three—Install PHP

PHP is an open source web scripting language that is widely use to build dynamic webpages.

To install PHP, open terminal and type in this command.

sudo apt-get install php5 libapache2-mod-php5 php5-mcrypt

After you answer yes to the prompt twice, PHP will install itself.

It may also be useful to add php to the directory index, to serve the relevant php index files:

sudo nano /etc/apache2/mods-enabled/dir.conf

Add index.php to the beginning of index files. The page should now look like this:

<IfModule mod_dir.c>

          DirectoryIndex index.php index.html index.cgi index.php index.xhtml index.htm


PHP Modules

PHP also has a variety of useful libraries and modules that you can
add onto your virtual server. You can see the libraries that are

apt-cache search php5-

Terminal will then display the list of possible modules. The beginning looks like this:

php5-cgi - server-side, HTML-embedded scripting language (CGI binary)
php5-cli - command-line interpreter for the php5 scripting language
php5-common - Common files for packages built from the php5 source
php5-curl - CURL module for php5
php5-dbg - Debug symbols for PHP5
php5-dev - Files for PHP5 module development
php5-gd - GD module for php5
php5-gmp - GMP module for php5
php5-ldap - LDAP module for php5
php5-mysql - MySQL module for php5
php5-odbc - ODBC module for php5
php5-pgsql - PostgreSQL module for php5
php5-pspell - pspell module for php5
php5-recode - recode module for php5
php5-snmp - SNMP module for php5
php5-sqlite - SQLite module for php5
php5-tidy - tidy module for php5
php5-xmlrpc - XML-RPC module for php5
php5-xsl - XSL module for php5
php5-adodb - Extension optimising the ADOdb database abstraction library
php5-auth-pam - A PHP5 extension for PAM authentication

Once you decide to install the module, type:

sudo apt-get install name of the module

You can install multiple libraries at once by separating the name of each module with a space.

Congratulations! You now have LAMP stack on your droplet!

Step Four—RESULTS: See PHP on your Server

Although LAMP is installed, we can still take a look and see the components online by creating a quick php info page

To set this up, first create a new file:

sudo nano /var/www/info.php

Add in the following line:


Then Save and Exit.

Restart apache so that all of the changes take effect:

sudo service apache2 restart

Finish up by visiting your php info page (make sure you replace the
example ip address with your correct one):

It should look similar to this.

original source :

About iptables

iptables is a command-line firewall utility that uses policy chains to allow or block traffic. When a connection tries to establish itself on your system, iptables looks for a rule in its list to match it to. If it doesn’t find one, it resorts to the default action.

iptables almost always comes pre-installed on any Linux distribution. To update/install it, just retrieve the iptables package:

sudo apt-get install iptables

There are GUI alternatives to iptables like Firestarter, but iptables isn’t really that hard once you have a few commands down. You want to be extremely careful when configuring iptables rules, particularly if you’re SSH’d into a server, because one wrong command can permanently lock you out until it’s manually fixed at the physical machine.

Types of Chains

iptables uses three different chains: input, forward, and output.

Input – This chain is used to control the behavior for incoming connections. For example, if a user attempts to SSH into your PC/server, iptables will attempt to match the IP address and port to a rule in the input chain.

Forward – This chain is used for incoming connections that aren’t actually being delivered locally. Think of a router – data is always being sent to it but rarely actually destined for the router itself; the data is just forwarded to its target. Unless you’re doing some kind of routing, NATing, or something else on your system that requires forwarding, you won’t even use this chain.

There’s one sure-fire way to check whether or not your system uses/needs the forward chain.

iptables -L -v

The screenshot above is of a server that’s been running for a few weeks and has no restrictions on incoming or outgoing connections. As you can see, the input chain has processed 11GB of packets and the output chain has processed 17GB. The forward chain, on the other hand, has not needed to process a single packet. This is because the server isn’t doing any kind of forwarding or being used as a pass-through device.

Output – This chain is used for outgoing connections. For example, if you try to ping, iptables will check its output chain to see what the rules are regarding ping and before making a decision to allow or deny the connection attempt.

The caveat

Even though pinging an external host seems like something that would only need to traverse the output chain, keep in mind that to return the data, the input chain will be used as well. When using iptables to lock down your system, remember that a lot of protocols will require two-way communication, so both the input and output chains will need to be configured properly. SSH is a common protocol that people forget to allow on both chains.

Policy Chain Default Behavior

Before going in and configuring specific rules, you’ll want to decide what you want the default behavior of the three chains to be. In other words, what do you want iptables to do if the connection doesn’t match any existing rules?

To see what your policy chains are currently configured to do with unmatched traffic, run theiptables -L command.

As you can see, we also used the grep command to give us cleaner output. In that screenshot, our chains are currently figured to accept traffic.

More times than not, you’ll want your system to accept connections by default. Unless you’ve changed the policy chain rules previously, this setting should already be configured. Either way, here’s the command to accept connections by default:

iptables --policy INPUT ACCEPT
iptables --policy OUTPUT ACCEPT
iptables --policy FORWARD ACCEPT

By defaulting to the accept rule, you can then use iptables to deny specific IP addresses or port numbers, while continuing to accept all other connections. We’ll get to those commands in a minute.

If you would rather deny all connections and manually specify which ones you want to allow to connect, you should change the default policy of your chains to drop. Doing this would probably only be useful for servers that contain sensitive information and only ever have the same IP addresses connect to them.

iptables --policy INPUT DROP
iptables --policy OUTPUT DROP
iptables --policy FORWARD DROP

Connection-specific Responses

With your default chain policies configured, you can start adding rules to iptables so it knows what to do when it encounters a connection from or to a particular IP address or port. In this guide, we’re going to go over the three most basic and commonly used “responses”.

Accept – Allow the connection.

Drop – Drop the connection, act like it never happened. This is best if you don’t want the source to realize your system exists.

Reject – Don’t allow the connection, but send back an error. This is best if you don’t want a particular source to connect to your system, but you want them to know that your firewall blocked them.

The best way to show the difference between these three rules is to show what it looks like when a PC tries to ping a Linux machine with iptables configured for each one of these settings.

Allowing the connection:

Dropping the connection:

Rejecting the connection:

Allowing or Blocking Specific Connections

With your policy chains configured, you can now configure iptables to allow or block specific addresses, address ranges, and ports. In these examples, we’ll set the connections to DROP, but you can switch them to ACCEPT or REJECT, depending on your needs and how you configured your policy chains.

Note: In these examples, we’re going to use iptables -A to append rules to the existing chain. iptables starts at the top of its list and goes through each rule until it finds one that it matches. If you need to insert a rule above another, you can use iptables -I [chain] [number] to specify the number it should be in the list.

Connections from a single IP address

This example shows how to block all connections from the IP address

iptables -A INPUT -s -j DROP

Connections from a range of IP addresses

This example shows how to block all of the IP addresses in the network range. You can use a netmask or standard slash notation to specify the range of IP addresses.

iptables -A INPUT -s -j DROP


iptables -A INPUT -s -j DROP

Connections to a specific port

This example shows how to block SSH connections from

iptables -A INPUT -p tcp --dport ssh -s -j DROP

You can replace “ssh” with any protocol or port number. The -p tcp part of the code tells iptables what kind of connection the protocol uses.  If you were blocking a protocol that uses UDP rather than TCP, then -p udp would be necessary instead.

This example shows how to block SSH connections from any IP address.

iptables -A INPUT -p tcp --dport ssh -j DROP

Connection States

As we mentioned earlier, a lot of protocols are going to require two-way communication. For example, if you want to allow SSH connections to your system, the input and output chains are going to need a rule added to them. But, what if you only want SSH coming into your system to be allowed? Won’t adding a rule to the output chain also allow outgoing SSH attempts?

That’s where connection states come in, which give you the capability you’d need to allow two way communication but only allow one way connections to be established. Take a look at this example, where SSH connections FROM are permitted, but SSH connections TO are not. However, the system is permitted to send back information over SSH as long as the session has already been established, which makes SSH communication possible between these two hosts.

iptables -A INPUT -p tcp --dport ssh -s -m state --state NEW,ESTABLISHED -j ACCEPT

iptables -A OUTPUT -p tcp --sport 22 -d -m state --state ESTABLISHED -j ACCEPT

Saving Changes

The changes that you make to your iptables rules will be scrapped the next time that the iptables service gets restarted unless you execute a command to save the changes.  This command can differ depending on your distribution:


sudo /sbin/iptables-save

Red Hat / CentOS:

/sbin/service iptables save


/etc/init.d/iptables save

Other Commands

List the currently configured iptables rules:

iptables -L

Adding the -v option will give you packet and byte information, and adding -n will list everything numerically. In other words – hostnames, protocols, and networks are listed as numbers.

To clear all the currently configured rules, you can issue the flush command.

iptables -F