In order to install Certbot on your server, follow the next steps: (make sure you have “git” installed on your system)
$sudo apt-get install git (if not previously installed)
$sudo git clone https://github.com/certbot/certbot
Running the above commands will download the Certbot latest release from their git repo in the /opt folder. Then we need to stop any service that might be using port 80 on our server, since the installation type we will be performing on this tutorial is the “standalone” type described on the Cerbot documentation, there are other ways to install the certificates, it is up to your preference.
Since this tutorial is about Pound, we are assuming the daemon is already installed so we need to stop it:
$sudo service pound stop
once the service is stopped, run:
$sudo ./letsencrypt-auto --text --email YOUR@EMAIL -d YOUR_DOMAIN --agree-tos --standalone certonly
by default, running the command above will generate the necessary key files (*.pem) in the following folder:
now, we need to create a private key file that Pound can understand, to do so run the following:
$sudo cat /etc/letsencrypt/live/YOUR_DOMAIN/privkey.pem /etc/letsencrypt/live/YOUR_DOMAIN/fullchain.pem > /etc/ssl/YOUR_DOMAIN.pem
doing so, will concatenate the privkey.pem file and the fullchain.pem file generated by Cerbot into a single file that will be stored into your ssl certificates folder, this is very important! Continue reading “Let’s Encrypt service with Pound server” »
There are two plugins that must be installed:
Install both of these plugins, from within Thunderbird (Menu button | Plugins | See all and then search for Lightning and then Provider for Google. Click Add to Thunderbird and then, when prompted, restart the app).
Once these have been installed, and Thunderbird restarted, you’re ready to configure.
Adding a Google Calendar
Open up the Lightning calendar tab (click on the Lightning icon in the top right corner of the Thunderbird window). Right-click a blank spot in the Calendar pane (left side of the window) and click New Calendar. In the resulting window (Figure A), click On the Network and then click Next.
Created with GIMP
Creating a new calendar in Lightning.
In the Locate your calendar window (Figure B), select Google Calendar, and click Next. Continue reading “Add Google Calendar to Thunderbird Mail Client” »
In this guide, we’ll walk you through installing all of these components (except for Linux, which is already installed as your OS when you create the server).
Install the Extra Packages for Enterprise Linux Repository (or EPEL for short):sudo yum install epel-release
Run a yum update to sync your packages with the new EPEL repository:
sudo yum update
sudo yum install mysql-server
sudo service mysqld start
Configure your MySQL installation:
Make it so that MySQL will start automatically on server reboot: Continue reading “LEMP on Centos 6” »
Once we installed Zimbra Collaboration, we need to be aware of some additional configurations that will allow us to send emails to other Email systems with an improve Security, such Gmail, Hotmail, Yahoo!, etc. This Wiki article will show the different Email Protection resources that exists, depends of the volume of sent email, will be better to implement only one, or two, or maybe all of them, depends.
Sender Policy Framework (SPF) is an email validation system, designed to prevent unwanted emails using a spoofing system. To check this common security problem, SPF going to verify the source IP of the email and compare it with a DNS TXT record with a SPF content.
Where needs to be configured?
SPF needs to be configured in the Public DNS Continue reading “Best Practices on Email Protection: SPF, DKIM and DMARC” »
Ericsson and Nokia, the number two and three suppliers, have their debt rated as junk. Verizon is selling, what should have been its future, their cloud business, to IBM. AT&T is loosing wireless subscribers every quarter. Telefonica, the innovation leader, is scaling back its IoT Smart City business. Telecom as an industry is getting to a crossroad. Whatever road they take will decide their future. The closest resemblance is the moment IBM discovered that PCs and servers were a commodity. They decided to become a services and software company. Competitors of them did not. These competitors might not be around for many more years. Communication has been commoditised. Calls and SMSes are dead. Long live WhatsApp and others! Even Twilio, the SMS and call disruptor, is having problems. Continue reading “Telecom is at a crossroad. The telecom business is starting to fail.” »
Last week, I found myself with a server under low load, but it couldn’t make or receive network connections. When I ran dmesg, I found the following line repeating over and over:
ip_conntrack: table full, dropping packet
I’d seen this message before, but I headed over to Red Hat’s site for more details. It turns out that the server was running iptables, but it was under a very heavy load and also handling a high volume of network connections. Generally, the ip_conntrack_max is set to the total MB of RAM installed multiplied by 16. However, this server had 4GB of RAM, but ip_conntrack_max was set to 65536:
# cat /proc/sys/net/ipv4/ip_conntrack_max
I logged into another server with 1GB of RAM (RHES 5, 32-bit) and another with 2GB of RAM (RHES 4, 64-bit), and both had ip_conntrack_max set to 65536. I’m not sure if this is a known Red Hat issue, or if it’s just set to a standard value out of the box. Continue reading “ip_conntrack table full, dropping packet” »
১. ওমরাহর ইহরাম (ফরজ)
· পরিষ্কার-পরিচ্ছন্নতা সেরে গোসল বা অজু করে নিতে হবে
· মিকাত অতিক্রমের আগেই সেলাইবিহীন একটি সাদা কাপড় পরিধান করুন, অন্যটি গায়ে জড়িয়ে নিয়ে ইহরামের নিয়তে দুই রাকাত নামাজ পড়ে নিন
· শুধু ওমরাহর নিয়ত করে এক বা তিনবার তালবিয়া পড়ে নিন Continue reading “ওমরাহর নিয়ম” »
I always try to share what I learn, and a few days back was looking for a single page short cut summary notes on various RAID level for the storage units. Found this article quite resourceful and exactly a single paged document that I was looking for.
Now sharing the content for the readers. Enjoy!
RAID 0 (STRIPE)
RAID 0 splits data across drives, resulting in higher data throughput. The performance of this configuration is extremely high, but a loss of any drive in the array will result in data loss. This level is commonly referred to as striping.
- Minimum number of drives required: 2
- Performance: High
- Redundancy: Low
- Efficiency: High
Continue reading “Understanding RAID” »
Part 1: Introduction to the terminology
It is not an uncommon situation, for early adopters of newly introduced concepts and technologies, to be totally confused when these can fundamentally change the ways of developing and delivering services. Especially when everybody talks about something like Docker, and how awesome and game changing it is. This confusion happens when we try things early on and rushing straight to testing them without grasping the whole concept and background of this newly introduced technology.
This is why you may have abandoned the whole trend of Linux containers, or because you read some controversial article from yea sayers and naysayers. In this first part, of a series of articles, we will try our best to clear things up and put everything on the right perspective for any developer, sysadmins, Q/A engineers or even enthusiasts who just need the right inspiration to use Linux containers and solve their special IT problems.
We will start from the beginning, with some necessary description of the historical events and concepts and then I will showcase how we can start working with Docker containers. This way, you will be able to understand “what led to the creation of containers”, “what are the building blocks” and “how do they work”. Continue reading “GoodReads: How to use Docker in a practical way (part 1 – Introduction)” »