How to combine two graphs on Cacti

Cacti is a fantastic open source network monitoring system that is widely used to graph network elements like bandwidth, storage, processor and memory utilization. Using its web based interface, you can create and organize graphs easily. However, some advanced features like merging graphs, creating aggregate graphs using multiple sources, migration of Cacti to another server […]
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How to replicate a MySQL database on Linux

Database replication is a technique where a given database is copied to one or more locations, so that the reliability, fault-tolerance or accessibility of the database can be improved. Replication can be snapshot-based (where entire data is simply copied over to another location), merge-based (where two or more databases are merged into one), or transaction-based […]
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What are good open-source log monitoring tools on Linux

In an operating system, logs are all about keeping track of events, be it critical system errors, resource usage warnings, transaction history, application status, or user activities. These logs, which are stored as (text or binary) files in the system, are useful for system auditing, debugging and maintenance. However, with so many different system entities […]
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How to manage remote MySQL databases on Linux VPS using a GUI tool

If you need to run a MySQL server on a remote VPS instance, how will you manage databases hosted by the server remotely? Perhaps web-based database administration tools such as phpMyAdmin or Adminer will first come to mind. These web-based management tools require a backend web server and PHP engine up and running. However, if […]
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How to secure BGP sessions using authentication on Quagga

The BGP protocol runs over TCP, and as such, it inherits all the vulnerabilities of a TCP connection. For example, within a BGP session, an attacker may impersonate a legitimate BGP neighbor, and convince the BGP routers on the other end to share their routing information with the attacker. The problem occurs when the attacker […]
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How to set up server monitoring system with Monit

Many Linux admins rely on a centralized remote monitoring system (e.g., Nagios or Cacti) to check the health of their network infrastructure. While centralized monitoring makes an admin’s life easy when dealing with many hosts and devices, a dedicated monitoring box obviously becomes a single point of failure; if the monitoring box goes down or […]
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How to perform BGP traffic engineering using Quagga on Linux

The previous tutorials demonstrated how we can turn a CentOS box into a BGP router and filter BGP prefixes using Quagga. Now that we understand basic BGP configuration, we will examine in this tutorial how to perform more advanced traffic engineering on Quagga. More specifically, we will show how we can influence the routing path […]
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How to set up IPv6 BGP peering and filtering in Quagga BGP router

In the previous tutorials, we demonstrated how we can set up a full-fledged BGP router and configure prefix filtering with Quagga. In this tutorial, we are going to show you how we can set up IPv6 BGP peering and advertise IPv6 prefixes through BGP. We will also demonstrate how we can filter IPv6 prefixes advertised […]
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How to make remote incremental backup of LUKS-encrypted disk/partition

Some of us have our hard drives at home or on a VPS encrypted by Linux Unified Key Setup (LUKS) for security reasons, and these drives can quickly grow to tens or hundreds of GBs in size. So while we enjoy the security of our LUKS device, we may start to think about a possible […]
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How to analyze and view Apache web server logs interactively on Linux

Whether you are in the web hosting business, or run a few web sites on a VPS yourself, chances are you want to display visitor statistics such as top visitors, requested files (dynamic or static), used bandwidth, client browsers, and referring sites, and so forth. GoAccess is a command-line log analyzer and interactive viewer for […]
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