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Posts Tagged ‘linux security’

Basic Linux Security for Beginners – Need to Understand the Basics!

June 9th, 2011 No comments

http://ubuntard.com/wp-content/uploads/2009/11/hackers0.jpgToday, safety is the prime concern in the online world. This type of issue can affect each and every person in several ways. These days, many system administrators are thinking to protect their system from unwanted applications and most importantly from hackers.

Now, there are several types of security packages available through which system users are protecting their system successfully. However, Linux is one of the best security packages among other security applications.

As per the present market scenario, Linux security package has managed to draw more importance from system users due to offer strong defense programs, and good services. If you want to take chance for using the Linux security at your system, then you need to understand basic things of the Linux. The basic of Linux security has described in the user’s manual which are available at online media.

Often, you can get the details about Linux security from web hosting service providers. At the time of installation of Linux in your PC, you don’t have to configure your windows. However, you will need an online connection at your system so that you can easily setup the Linux security in your system. The Linux security is directly connected to the TCP and IP protocol.

When the system is set up, then there are some routine tasks that will further improve the security: Remove mention of the Linux distribution as well as version numbers from the banner files such as /etc/issue as well as /etc/issue.net Add warnings regarding unauthorised use & logging to the system banners Configure the daemons that is named to listen on interfaces you would like them on.

In case, you actually want to nail down system, then consider installing & running the comprehensive system script such as Bastille Linux (http://www.bastille-linux.org/). It makes plenty of the detailed changes on the system.

As Bastille runs, that tells you what is it doing; you may select to skip some steps, however you can certainly learn much about the security all along way.

One of worst things that will happen is for the attacker to compromise the system, pilfer files, as well as then make use of system to launch attack on another victim, whereas you sit blissfully not aware of what is going on. In order, to ensure that the alarm bells ring while someone tampers with setup, then you must install the intrusion detection system.

Categories: linux, Security Tags: ,

Basic Linux Security for Beginners Part II

May 30th, 2011 No comments

http://i.ytimg.com/vi/Kys3y9NQqNs/0.jpgBasic Linux securities for beginners are more important for the system or Internet users to secure their system data from the hackers. Linux security users have a few inbuilt advantages more their equals like the Windows users in case of security.

Linux is much secure and effective than the Windows based systems. However, the Linux systems have the less frequently instead of the Windows systems.  On the other hand, many users have focused to disconnect the network connection, switched off from their system for better security reasons.

These processes may some how secure but it is not a long term solution that every user faces to protecting servers from the outside intrusion.

Now day’s there are many computer systems connecting with the Internet directly or through the local area networks. So, it is much difficult or expensive for the user to make any sorts of change in their system setting for the security reasons.

However, the user can avoid the security problem from their without disconnect the network connection from their system only by the proper planning and change the system configuration to create a better security environment. In this regard, the users only want to follow the basic Linux security for beginners.

It comes in 2 basic flavours: the host integrity verification, as well as network intrusion detection. The host inegrity verification system that makes snapshot of critical files on the system: configuration files in /etc, binary program files in the /bin, /sbin, /lib as well as under /usr, the critical files in /var, many more.

In order, to do this, that records fingerprint for every file: file pathname, date or time stamps, size, permissions and ownership, inode number as well as most importantly – MD5 of file’s contents.

That stores all information in digitally signed database, then runs the periodic checks and see in case, anything has changed. Obviously, in case, it has, then you know somebody is of no good.

Examples of the host integrity verification include Tripwire that is included in a lot of distributions & AIDE. Both of these have to get set up before hand of system to be exposed to shark infested waters of Internet, but; in case, you have not prepared before hand and you are also concerned your system may have the root kit to be installed, then try to chkrootkit.

Categories: linux, Security Tags:

Iptables – Easily Defining the Chains of Rules!

May 27th, 2011 No comments

http://www.gege.org/iptables/images/shot2.gifIptables is one of the latest userspace applications that have been designed to configure the Linux 2.6.x, 2.4.x, and IPv4 packet filtering rule set. It has been primarily targeted towards the system users.

The Iptables has been designed to operate like as Network Address Translation for making configure the packet filter ruleset.

The Iptables packet is also involves Ip6tables and it can be used for configuring the IPv6 packet filter.

This packet is requiring a kernel, and it is loaded with 2.4.x and 2.6.x for releasing the kernel. The Iptables is having some good features, and the features are discussed below.

  • Iptables can list the contents of the packet filter ruleset
  • It can help the user to add, remove and modify the rules in the packet filter ruleset
  • The system administration can list and zeroing per rule counters of the packet filter ruleset

One of the best advantages of the Iptables is that it is allowing the users to define the tables contains chains of rules. Specially, the user can get much help to use the Linux version successfully.

Now, you can get the details about the Iptables from users manual. The Iptables has been loaded with tons of rules and these rules are the combinations of treatment packet processing.

QUEUE means passing packet to the user space. (How packet is received by the user space process varies by particular queue handler. 2.4.x n 2.6.x kernels to 2.6.13 include ip_queue queue handler. ACCEPT actually means to let packet through and DROP means dropping packet on floor.

The kernels 2.6.14 & later additionally include nfnetlink_queue handler. The packets with target of the QUEUE is sent to the queue number ‘0’ at this case. So, please see NFQUEUE target as it is described later in man page.)

RETURN actually means stop traversing chain & resume at next rule in previous chain. In case, end of the built in chain is been reached or rule in built in chain with the target RETURN is been matched, target specified by chain policy decides fate of a packet. These choices specify specific action to do.

Just one of them is specified on command line otherwise specified below. So, for all long versions of command & option names, you have to use enough letters to make sure iptables will differentiate that from other options.

Categories: Security Tags: ,

Basic Linux security for beginners – Save Your Computers from Attackers!

March 27th, 2011 No comments

http://www.faunos.com/wp-content/uploads/cc/ssh_linux_command3.jpg

Now day’s safety is one of the most important parts on the Internet world. Security is such a type of thing that can affect every computer users. Now day’s many people are worry about the security factor of their system.

Computer hackers are the most important problematic issue in the online world today. However, there are many security packages invented to protect the system from hacking and also from other hazards. By using such packages system administrators can protect their system from hacking. In the current days Linux is one of the ideal security packages for beginners.

Due to such strong defense program Linux has managed more attention for the system administrators. By understanding some basic things about Linux you can use the Linux security program on your computer.

By going online you can find basic Linux security described in the user’s manual. From web hosting service provider you can easily get some detail about Linux security. For easy set up of Linux security you need an online connection for your system. Linux security

packages perform under TCP and IP protocol. It is a great advantage for beginners to use Linux security packages and save their computers from getting any type of hazards.

Whereas there are far, fewer worms & viruses for the Linux, and there are a few script kiddie attacks as well as vulnerabilities in the major subsystems from every time.
With this in your mind, here is a few advice for about to connect the Linux system to Internet for first time. While planning the installation, you may take benefit of a few of kernel’s features to make system tougher target. For instance, kernel will mount filesystems read only.

So, by making /usr subdirectory the separate file system, you may mount that read only that makes it more difficult for attacker to upload the root kit or modify files in /usr.

In case, you are concerned about the physical security, then you must password protect BIOS settings so attacker will not boot a system off floppy and CD ROM, and you must as well password protect boot loader (LILO and GRUB) configuration so she will not change kernel command line.

The Modern Linux systems generally make use of MD5 that generates 128bit hash from the arbitrary length input as well as is much, harder to crack.

 

Categories: linux, Security Tags: ,

Iptables – It’s a Perfect For Cheap Security!

March 23rd, 2011 No comments

http://it.megocollector.com/wp-content/uploads/2008/09/putty-disable-firewall.jpgIptables is also known as the user space utility which is a kind of program that needs to be operated by the root users, otherwise it may lack in the performance level. You can take Iptables as a service because this has not been considered as an essential binary. With this sort of approach with the Iptables, the location for such program will remain at the /user/sbin. In order to refer the components located at the kennel level Iptables can also be used. It’s the kennel level which has been termed as the x tables and also carries several codes that are the shared portion. These shared codes have been used by the basic four modules that are also representing the API which is in use for the extension purposes. Additionally x tables are also in use to represent the entire firewall structure in a hassle free manner.

This sort of addition is also allowing the system administrator to explain certain kind of tables that comprises of chains and certain rules that can treat the packets. These tables are linked with several packet processing. Packets can be processed by traversing the rules in chains. Rules in the chain can make the right call for go to or jump to other chain like option and this sort of facility can be repeated for your desired nesting. In case, the packet comes from machine (is made by the application running on the machine), it may go to OUTPUT chain.

The packet coming to machine traverses INPUT chain.

The packet now going somewhere makes use of FORWARD.

http://www.codero.com/knowledge-base/images/linux_secure_2.JPG

That is not how IPCHAINS works. The packet going somewhere do not see the INPUT with the iptables. In the same way, forwarded packet do not see OUTPUT chain with the iptables. In a few ways it makes iptables simpler to understand, however in case, you have ipchains stuck in the head, that makes it very confusing. One more major difference is iptables is very stateful; this is, that keeps track of every connection. You may look at the connections just by examining /proc or net ip_connact. Here is a bit from the machine:

You need ip_connact module having iptables understand relationship between control & data sides of ftp connection. In case, it makes not any sense now, you may want to read ftp section in Security or dslsecure.html.

 

 

 

 

Basic Linux security for beginners – Provide Security for Beginners!

March 21st, 2011 No comments

http://www.simplehelp.net/images/ssh_port/03.png

Security is one of the major problems for the internet users today. It is affects every user in their smooth work.

It is a big concern for the user if you are using Linux operating system.

Although Linux is one of the best operating system but there are some concern about the security issue of Linux operating system, especially for beginners.

Therefore, it is necessary for beginners to know the procedure to keep their system secure enough for safe usage. One of the best things you can do to secure your system by stay aware about the security concern.

If you are a beginner then you have to know some security tips to protect your computer from any type of damage.  As a beginner you don’t have to be a security guru to be safe but you have to know some basic thing to safe your system.

You have to understand the principles of the TCP/IP protocol before knowing something about security. Tcp and udp are the two parts of TCP/IP protocol. The main difference between tcp and udp is the tcp is connection oriented but the udp is connectionless.

Both tcp and udp have several advantages and disadvantages and they both are used differently. The traditional UNIX systems encrypted users’ passwords using algorithm named salt+crypt and after that stored then the results in /etc/passwd file.

On the login, system will take login password, encrypt that in same way as well as compare that with entry in /etc/passwd. In case, two agreed, then user was been considered authenticated. Solution to first problem was to switch to stronger encryption algorithm.

There are 2 problems with this and first, there is fact that, whereas salt+crypt is one-way algorithm (and you will not decrypt contents of /etc/passwd) it is not strong, as well as is limited to 8 character passwords.

Worse, file /etc/passwd needs to get readable by users, as that relates the user ID numbers to names, and locates home directories as well as has other information regarding the users.

It makes vulnerable to the so called dictionary attacks, where attacker takes dictionary (many systems have for the spell checking), encrypts each word in that, and after that compares them against encrypted passwords in /etc/passwd.

While match is found, attacker just looks up corresponding word in dictionary & this is password.

 

Categories: linux, Security Tags: ,

Basic Linux Security for Beginners – Need to Understand the Basic!

March 20th, 2011 No comments

http://www.linux-herunterladen.de/bilder/lINUX_Tux.svg.png

Today, safety is the prime concern in the online world. This type of issue can affect each and every person in several ways. These days, many system administrators are thinking to protect their system from unwanted applications and most importantly from hackers.

Now, there are several types of security packages available through which system users are protecting their system successfully. However, Linux is one of the best operating systems and provide the best in terms of security packages among other security applications.

As per the present market scenario, Linux security package has managed to draw more importance from system users due to offer strong defense programs, and good services. If you want to take chance for using the Linux security at your system, then you need to understand basic things of the Linux.

The basic of Linux security has described in the user’s manual which are available at online media. Often, you can get the details about Linux security from web hosting service providers. At the time of installation of Linux in your PC, you don’t have to configure your windows. However, you will need an online connection at your system so that you can easily setup the Linux security in your system. The Linux security is directly connected to the TCP and IP protocol.

When the system is set up, then there are some routine tasks that will further improve the security: Remove mention of the Linux distribution as well as version numbers from the banner files such as /etc/issue as well as /etc/issue.net Add warnings regarding unauthorised use & logging to the system banners Configure the daemons that is named to listen on interfaces you would like them on.

In case, you actually want to nail down system, then consider installing & running the comprehensive system script such as Bastille Linux (http://www.bastille-linux.org/). It makes plenty of the detailed changes on the system.

As Bastille runs, that tells you what is it doing; you may select to skip some steps, however you can certainly learn much about the security all along way. One of worst things that will happen is for the attacker to compromise the system, pilfer files, as well as then make use of system to launch attack on another victim, whereas you sit blissfully not aware of what is going on. In order, to ensure that the alarm bells ring while someone tampers with setup, then you must install the intrusion detection system.

Categories: linux, Security Tags: ,