How to Authenticate Against openLDAP Without Knowing DN Using java

In fact you can’t do it without knowing DN! There is an anonymous access in openLDAP which is enabled by default. The anonymous access let one to query(search filter) openLDAP without knowing bind username/password. Run following command on your openLDAP server : ldapwhoami -H ldap:// -x If you get “anonymous” as result you are all […]

How to use CompletableFuture in SpringBoot 2

In Spring Boot there is an annotation @Async to assist developers for developing concurrent applications. But using this feature is quite tricky. In this blog we will see how to use this feature along with CompletableFuture. I assumed you know the drill about CompletableFuture, so I won’t repeat the concept here. First of all you […]

Installing openLDAP and Making it Replicable

OpenLDAP installation is fairly straight-forward and doesn’t have any caveats, but making it replicable has ambiguity. We will start with installing openLDAP. I will use following configs : ubuntu 16.04 server openLDAP 2.4.x phpLDAPadmin Installing openLDAP : First thing first, update your ubuntu box : sudo apt-get update Install openLDAP : sudo apt-get install slapd […]

How to Configure Iptables in Stateful Mode Properly

Iptables is a software firewall based on Netfilter, in fact it’s a framework for working with Netfilter. Generally firewalls have two modes, stateless and stateful. In this post we will study a brief of how to configure Netfilter in stateful mode. I’m going to assume your linux box is fresh installation and doesn’t have any […]

Enabling LDAP on Linux and local user’s session will interchange with LDAP’s user intermittently

Let’s say you have a central authentication server in a LDAP and you successfully connect your Linux box as a client to LDAP server. Whenever you are using a particular LDAP user to login to your box, your shell get confused and change the LDAP user with a local user of your box¬†intermittently. What is […]

After configuring Ubuntu to use LDAP ssh login become too slow

This is a common symptom of mis behaviour of systemd-logind. I couldn’t still find-out what is really happening underneath of this service but if you experience such issues you can try to restart the service using following command sudo service systemd-logind restart and make sure to run this code on the console not just by […]

How to install maven on Ubuntu manually with any specific version

For installing Maven on Ubuntu you have two ways¬† the easy way and the manual method. The easy way is just execute following command : sudo apt-get install maven Or if you use Ubuntu 16+ you can use following command too : sudo apt install maven Just remember you need to have root privileges. The […]

How to install JDK on Ubuntu

Installing Java JDK is easy and straightforward in Windows and OSX but not in Ubuntu. Here is how I am installing JDK on Ubuntu. Download the latest JDK package from Oracle website. If you don’t know which file to choose you ought to select .tar.gz files whether 32bit or 64bit depends on your requirements. after […]