How to verify a checksum in Linux?

Introduction In this article we will learn how to calculate and verify a checksum of a file in Ubuntu. We will also see what a checksum actually is and why we should care. You can jump straight to the CLI commands. What is a checksum? A checksum (also called a hash or a digest) is

How to bypass SIP blocking by ISP?

Introduction In this article we will see how we can bypass SIP traffic blocking. There are a lot of countries where local ISPs block SIP traffic. It makes it impossible for enterprises or private persons to leverage from low rates on international calls provided by various SIP trunk providers. Solution One of the solutions is

OpenLDAP operations (ldappasswd).

Introduction. In this post we will see how we can reset password for our OpenLDAP users using the special utility ldappasswd. Change user password using admin credentials. When it comes to resetting user passwords, one of the most common things is to reset user’s password providing our admin credentials. Let’s change the password for the

OpenLDAP operations (ldapadd).

Introduction This post will cover another important LDAP data manipulation – adding new entries to the directory tree. We will be using ldapadd utility. Prerequisite I assume that you have a working OpenLDAP server and OpenLDAP client. You might want to read this post which explains step by step how to install and run OpenLDAP

OpenLDAP operations (ldapsearch).

Introduction In this post we will learn how to search OpenLDAP directory using ldapsearch command. Prerequisite I assume that you have a working OpenLDAP server and OpenLDAP client. You might want to read this post which explains step by step how to install and run OpenLDAP server on Ubuntu 18.04. It also shows the basic

How to Install OpenLDAP on Ubuntu 18.04?

Introduction In this post we will install OpenLDAP on Ubuntu 18.04. OpenLDAP is a free open-source implementation of LDAP (Lightweight Directory Access Protocol). LDAP is a datastore mostly used for storing user identities and for user authentication. What is LDAP? LDAP stores the information in a hierarchical format called Directory Information Tree(DIT). The DIT contains

Linux ss Command Examples

Introduction In this post we will learn how to use ss command, which can give you a lot of useful socket related information. ss comes pre-installed with all modern popular Linux distributions. We will go through several examples, so you could easily modify them and get the desired result. I will be using Ubuntu 18.04

Shared Lines in FreePBX.

Introduction In this post you will learn how to configure multiple IP phones with the same extension in FreePBX. This extension is usually called shared line, because it is shared by different devices. Using shared lines is very convenient when you have two or more devices and want to be able to answer the incoming

Cisco IP Phone “Host Not Found” error.

Introduction This post explains why you are getting “Host Not Found” error on your newly registered IP phone’s display and how to fix it. Why “Host Not Found” error? The reason you are getting this error is that when you autoregister a brand new IP phone, it attempts to take you through the self-provision wizard,