MySQL replication is a process that allows you to easily maintain multiple copies of a MySQL data by having them copied automatically from a master to a slave database. Replication enables data from one MySQL database server (the master) to be copied to one or more MySQL database servers (the slaves). Replication is asynchronous by default; slaves do not need to be connected permanently to receive updates from the master. Depending on the configuration, you can replicate all databases, selected databases, or even selected tables within a database.MySQL is one of the most popular open source relational database management system (RDBMS). When your traffic grows then you need to increase the instances of your mysql server and have to replicate the data on multiple servers. MYSQL provide 2 ways to replicate data, master – master and master – slave.
The Nmap aka Network Mapper is an open source and a very versatile tool for Linux system/network administrators. Nmap is used for exploring networks, perform security scans, network audit and finding open ports on remote machine. It scans for Live hosts, Operating systems, packet filters and open ports running on remote hosts.
Understanding Open, Closed and Filtered
Nmap has a variety of scan types, understanding how the default and most common
SYN scan works is a good place to start to examine how the scan works and interpreting the results.
The 3 way TCP handshake
First a bit of background, during communication with a TCP service, a single connection is established with the TCP 3 way handshake. This involves a
SYN sent to an TCP open port that has a service bound to it, typical examples are HTTP (port 80), SMTP (port 25), POP3 (port 110) or SSH (port 22).
As security concern you can track your user command that are been executed over the bash terminal.even you can track the command which are executed as root/sudo.
Process management is an integral part of any modern-day operating system (OS). The OS must allocate resources to processes, enable processes to share and exchange information, protect the resources of each process from other processes and enable synchronization among processes. To meet these requirements, the OS must maintain a data structure for each process, which describes the state and resource ownership of that process, and which enables the OS to exert control over each process.
Memory Hierarchy gives the relationship between the speed, size and cost with respect to the distance from the Processor.
In the diagram above the peak of the pyramid represents the processor. The Register lies with in the processor itself hence are the closest to the processor and work the fastest. But the number of registers that can be included in a processor is limited, as it would lead to increase in processor size, increase in manufacturing cost etc. Thus the register memory is restricted to minimal.
A level below the register is the L1 cache or the first level cache. In the processors of today, the L1 cache also lies on the processor chip itself, though it might lie outside too.
The cache memory works at a very fast speed but is also extremely expensive as compared to the other memories available. This high cost is one of the major restriction why we can not use lots of cache in a computer even though it is faster.
The general thumb rule is, higher the cache memory faster would be the working of the processor.
The FortiGate unit supports both SSL and IPSec VPN technologies. Each combines encryption and VPN gateway functions to create private communication channels over the Internet, which helps to defray physical network costs. Both enable you to define and deploy network access and firewall policies using a single management tool. In addition, both support a simple client/user authentication process (including optional X.509 security certificates). You have the freedom to use both technologies; however, one may be better suited to the requirements of your situation.
In general, IPSec VPNs are a good choice for site-to-site connections where appliance-based firewalls are used to provide network protection, and company sanctioned client computers are issued to users. SSL VPNs are a good choice for roaming users who depend on a wide variety of thin-client computers to access enterprise applications and/or company resources from a remote location.
What does Virtualization mean?
The simple explanation is that you create a virtual version of something that’s generally used for some type of execution. For example, if you were to partition a basic hard drive to create two hard drives, then they would be two ‘virtualized hard drives,’ as the hardware is technically a single hard drive that was digitally separated into two.Virtualization refers to the creation of a virtual resource such as a server, desktop, operating system, file, storage or network.
what are Containers?
Containers are a lightweight virtualization technology.In IT it is all about the need to run an application, not a virtual machine.In the end, it is the application user that has a need.This need is to run the application and no user will ever ask for a virtual machine.That is exactly one of the major design goals of the container technology.
A container is a virtualization method at the OS level.This allows multiple instances of an os to be running on the same kernel, which allows for a more efficient usage of available resources.
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