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Showing posts from 2018

Listing Zimbra Accounts with Some Details

Recently I have to export the user list for a particular domain. Luckily Zimbra has Admin GUI with a search feature. When you search accounts, you can download search results as a comma-separated csv file. So I did a search and download the result file, but the result did not have all the columns I need and also there is no option for customizing columns for search results. So I had to write a bash script to get the desired list.
Here is the bash script ( It can be customized by adding or removing field names. Run it under zimbra user like ./ <domain_name_here> ):

Creating Multiple VLANs over Bonding Interfaces with Proper Routing on a Centos Linux Host

In this post, I am going to explain configuring multiple VLANs on a bond interface. First and foremost, I would like to describe the environment and give details of the infrastructure.
The server has 4 Ethernet links to a layer 3 switch with names:
enp3s0f0, enp3s0f1, enp4s0f0, enp4s0f1
There are two bond interfaces both configured as active-backup
bond0, bond1
enp4s0f0 and enp4s0f1 interfaces are bonded as bond0. Bond0 is for making ssh connections and management only so corresponding switch ports are not configured in trunk mode.
enp3s0f0 and enp3s0f1 interfaces are bonded as bond1. Bond1 is for data and corresponding switch ports are configured in trunk mode.
Bond0 is the default gateway for the server and has IP address
Bond1 has three subinterfaces with VLAN 4, 36, 41. IP addresses are,, respectively.
Proper communication with other servers on the network we should use routing tables. There are three rt_tables. Each of them is dedicated t…

Python Script for Generating Random Passwords

This Python script is practical for generating random passwords.

A password contains:
7 lowercase alphabetic characters.
2 uppercase alphabetic characters.
2 numeric characters.
1 special character. (special char will be one of these: ! + % ? * - _ )

3 Node (Master Slave Slave) Redis Cluster with Sentinel

It is possible to make your Redis cluster Fault Tolerant and Highly Available by building a replica set and then monitor these nodes using sentinel for automatic failover.
I am going to give an example setup to explain it. The structure is built with three nodes running one as a master and two as slaves.
Master Node: (Centos 7.2) Slave1 Node: (Centos 7.2) Slave2 Node: (Centos 7.2)
Edit System settings on each node: /etc/sysctl.conf
Disable transparent hugepage (transparent_hugepage=never) on each node: /etc/default/grub
Apply grub config and reboot each node:
Master Node: /etc/redis/6379.conf
Slave1 Node: /etc/redis/6379.conf
Slave2 Node: /etc/redis/6379.conf
Master Node: /etc/redis/sentinel.conf
Slave1 Node: /etc/redis/sentinel.conf
Slave2 Node: /etc/redis/sentinel.conf
Each Node: /etc/systemd/system/
Each Node: /etc/systemd/system/
After creating service files reload sy…