Tag: linux

  • Brief Introduction to Zimbra Internal Architecture

    In some cases, you might want to recover your data from Zimbra, or you may be curious about how Zimbra manages users and emails behind the scenes. I dug into Zimbra’s nuts and bolts because we lost Zimbra’s local LDAP, which took more than 3 days to fix, so I wanted to share what I […]

  • Provisioning DNS Server Using PowerDNS

    When you want to setup a DNS server on *nix platform, the first option that may cross your mind is bind9. But there are other options such as PowerDNS. In this post I’m going to show you how to setup a DNS server in single node mode. This DNS server is going to be authoritative […]

  • 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┬áintermittently. 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 traceroute a particular IP and Port?

    There are sometimes that you want to trace an IP/Host based on a particular port to check if the port is open or not here is how you can do that : traceroute -T -p 25 yoursite.com Breakdown : -T indicates to use TCP instead of UDP -p checks specific port Seyed Vahid HashemiMy chief […]

  • What does $? mean in linux?

    The $? is called exit code of an application used to run. As an example type following commands in console: top then press CTRL-Z and then type: echo $? You will see 147 as the answer. Return values more than 128 usually means signal and you have to do the calculation by subtracting 128 from […]