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Centos is most often used on Linux distribution web servers. It was been developed as a free alternative to commercial version of Red Hat, but the full binary compatibility has been preserved. Free Centos is compiled from published source codes of Red Hat Enterprise Linux (RHEL).
The users are provided with continuous manageable platform, which is suitable for a wide range of application modes. System stability is ensured by extensive testing of all packet updates. The users are provided with a solid and predictable framework for server along with the extensive resources to create, test, release, and support for custom code.
Stable operation is ensured by the fact that the program does not need a reboot during a long period time. Moreover, even when the driver of a new device or program for Centos is installed, you do not need to stop working because of a reboot. Only when you change the kernel you need to make a registry update, but the developers will eliminate this problem subsequently.
The work of virtual server without interruption was calculated even in Red Hat version, later integrated in Centos. The load balancing across multiple real servers is ensured by the programs designed for this process. Programs are supported by two routers, one of which works, and the other is passive. The passive one monitors the work of the active router, and in case of the failure of the latter takes over its function.
The problem of traffic analysis of the internal network and external Internet traffic additionally lies on the active router. All data passes through the LVS router. Both devices look like a single unit to the external network.
When you install a virtual server, the problem of protection of the system from unauthorized access occurs. In most cases, the system breach is not caused by its faults, but because of the illiterate administration or loss of alertness.
Linux operating system is used to transfer data over SSH protocol network. It is very well protected and to get access to the packets is virtually impossible.
User name and port of the SSH protocol is provided by the system, so the only protection way is to use the password. Therefore, to protect your data, please use the following rules:
- A complex password of uppercase and lowercase letters, numbers, punctuation marks.
- For remote access please create a new user, meaning, do not use ROOT to access the network.
- Change access port, that will be different from a standard SSH one.
- Write trusted IP-addresses, which can only receive data and you can send data to them.
- Using additional software will identify the attacker.
It is possible to configure the protection against unauthorized access in Centos. First of all hacking happens when your password is detects. Modern electronic systems make it easy to cycle through all the options in a relatively short period of time. Brut Force hacks into the systems, but there is protection from it.
- It is necessary to set the time interval between the attempts to connect to the server. For example, a few seconds. This period of time will not cause inconvenience to the authorized user, but will slow down brute.
- Define the timeout after several unsuccessful attempts. Even a 30 minutes timeout will extend the selection of the password for several months.
As mentioned above, Centos is based on the version of Red Hat, which is commercial and should be paid for. But Linux was originally free-of-charge operating system, so Centos was developed based on the Red Hat code as a free version.
Anyone can download this version of the program from the net, without financial cost. The same applies to any software installed within the system. Perhaps not all products provide advanced set of tools for graphic design or video editing, but the server's configuration, its administration takes place without any problems with the right software.
Evaluation of performance takes place in every particular setting, and it should be determined by the administrator alone. The following aspects influence on the system productivity:
- The amount of memory usage, both physical (hard disk), and operational. Lack of available or dedicated memory reduces system speed.
- The number of processor cores and its frequency. High CPU utilization can often point that it should be modernized.
- Disk request operations, for example, when working with databases, will accelerate or, on the contrary, slow down the work.
- Access to the server of a large number of users can reduce the response time.
There are several programs that are integrated in Centos in order to assess the productivity. The productivity level is evaluated by the appearance of the queue to the physical resource. If the queue consists of more than two processes, the resource is estimated as the bottleneck.
Thus, the effective monitoring uses snapshots of current performance to identify incorrectly configured processes.
Centos is a complete operating system that runs both on 32-bit and 64-bit architecture.
In the case of virtual servers reliability is ensured in several ways. First of all, virtual servers allow trouble-free operation even in cases when the server hardware fails. The work is transferred to another real server, but users will not even notice it.
Reliability is influenced by the stable work and regular backups. One of the most important conditions is the presence of a large variety of software to maintain the system in working condition.
Centos virtual server is reliable, fun, vital and free project.