Monday, September 19, 2016

How To Secure Your Redis Installation on Ubuntu 14.04

Introduction

Redis is an in-memory, NoSQL, key-value cache and store that can also be persisted to disk.
This tutorial shows how to implement basic security for a Redis server.
However, keep in mind that Redis was designed for use by trusted clients in a trusted environment, with no robust security features of its own. To underscore that point, here's a quote from the official Redis website:

How To Install and Use Redis

About Redis

Redis, developed in 2009, is a flexible, open-source, key value data store. Following in the footsteps of other NoSQL databases, such as Cassandra, CouchDB, and MongoDB, Redis allows the user to store vast amounts of data without the limits of a relational database. Additionally, it has also been compared to memcache and can be used, with its basic elements as a cache with persistence.
Note: Redis can be installed automatically on your Droplet by adding this script to its User Data when launching it. Check out this tutorial to learn more about Droplet User Data.

Setup

Before you install redis, there are a couple of prerequisites that need to be downloaded to make the installation as easy as possible.

Monday, May 30, 2016

Saturday, May 21, 2016

Wednesday, May 18, 2016

How To Configure and Validate DKIM Records on Zimbra

DKIM is one of many tips for increase reputation of email server besides SPF records who has been explained on previous article. On this section, i will do generate DKIM on Zimbra and configure DKIM records on public DNS using cPanel.

First, login to Zimbra server via SSH and generate DKIM
su - zimbra
/opt/zimbra/libexec/zmdkimkeyutil -a -d imanudin.net -s selector

The result of above command is like below
generate-dkim-zimbra
For records key DKIM is line on () starting with “v=DKIM1…..until double quote (“). Block and copy the records and check on website : http://dkimcore.org/tools/. Paste on key record for checking and validate.

Monday, May 9, 2016

How to Install MongoDB on CentOS 7


MongoDB is a NoSQL database intended for storing large amounts of data in document-oriented storage with dynamic schemas. NoSQL refers to a database with a data model other than the tabular format used in relational databases such as MySQL, PostgreSQL, and Microsoft SQL. MongoDB features include: full index support, replication, high availability, and auto-sharding.


Pre-Flight Check
  • These instructions are intended for installing MongoDB on a single CentOS 7 node.
  • I’ll be working from a Liquid Web Core Managed CentOS 7 server, and I’ll be logged in as root.

Thursday, May 5, 2016

Best command line tools for linux performance monitoring

Sometimes a system can be slow and many reasons can be the root cause. To identify the process that is consuming memory, disk I/O or processor capacity you need to use tools to see what is happening in an operation system.
There are many tools to monitor a GNU/Linux server. In this article, I am providing 7 monitoring tools and i hope it will help you.

Htop

Htop is an alternative of top command but it provides interactive system-monitor process-viewer and more user friendly output than top.
htop also provides a better way to navigate to any process using keyboard Up/Down keys as well as we can also operate it using mouse. For Check our previous post: How to install and use htop on RHEL/Centos and Fedora linux
Htop (Linux Process Monitoring)
Htop (Linux Process Monitoring)

dstat

Dstat is a versatile replacement for vmstatiostatnetstat and ifstatDstat overcomes some of their limitations and adds some extra features, more counters and flexibility. Dstat is handy for monitoring systems during performance tuning tests, benchmarks or troubleshooting.
Dstat allows you to view all of your system resources in real-time, you can eg. compare disk utilization in combination with interrupts from your IDE controller, or compare the network bandwidth numbers directly with the disk throughput (in the same interval).
Dstat gives you detailed selective information in columns and clearly indicates in what magnitude and unit the output is displayed. Less confusion, less mistakes. And most importantly, it makes it very easy to write plugins to collect your own counters and extend in ways you never expected.
Dstat’s output by default is designed for being interpreted by humans in real-time, however you can export details to CSV output to a file to be imported later into Gnumeric or Excel to generate graphs.
Example dstat output
Example dstat output

Collectl

Collectl is a light-weight performance monitoring tool capable of reporting interactively as well as logging to disk. It reports statistics on cpu, disk, infiniband, lustre, memory, network, nfs, process, quadrics, slabs and more in easy to read format.
In this article i will show you how to install and sample usage Collectl on Debian/Ubuntu and RHEL/Centos and Fedora linux.
Check our previous post: Collectl – Monitoring system resources
Collectl screen
Collectl screen

Nmon

nmon is a beutiful tool to monitor linux system performance. It works on LinuxIBM AIX UnixPower,x86amd64 and ARM based system such as Raspberry Pi. The nmon command displays and recordslocal system information. The command can run either in interactive or recording mode.
Check our previous post: Nmon – linux monitoring tools
nmon startup screen
nmon startup screen

Saidar

Saidar is a curses-based application to display system statistics. It use the libstatgrab library, which provides cross platform access to statistics about the system on which it’s run. Reported statistics includeCPUloadprocessesmemoryswapnetwork input and output and disks activities along with their free space.
Check our previous post: Saidar – system monitoring tool
saidar -c
saidar -c

Sar

The sar utility, which is part of the systat package, can be used to review history performance data on your serverSystem resource utilization can be seen for given time frames to help troubleshoot performance issues, or to optimize performance.
Check our previous post: Using Sar To Monitor System Performance
Sar command
Sar command

Glances

Glances is a cross-platform curses-based command line monitoring tool writen in Python which use the psutil library to grab informations from the system. Glance monitoring CPULoad AverageMemoryNetwork InterfacesDisk I/OProcessesand File System spaces utilization.
Glances can adapt dynamically the displayed information depending on the terminal siwrize. It can also work in a client/server mode for remote monitoring.
Glances
Glances

Atop

Atop is an interactive monitor to view the load on a Linux system. It shows the occupation of the most critical hardware resources on system level, i.e. cpu, memory, disk and network. It also shows which processes are responsible for the indicated load with respect to cpu- and memory load on process level. Disk load is shown if per process “storage accounting” is active in the kernel or if the kernel patch ‘cnt’ has been installed. Network load is only shown per process if the kernel patch ‘cnt’ has been installed.
Example Atop output
Atop linux resources monitoring tool
For more about Atop check next post: Atop – monitor system resources in linux
So, if you come across any other similar tool then let us know in the comment box below.