Posts by Category

Configure RabbitMQ failover cluster

RabbitMQ is a universal bus to be used to exchange messages between the applications. There are other solutions like Kafka, AWS SQS, Google Pubsub, etc. If y...

Change default umask for files in custom folder

Umask in Linux is a pattern of permissions for created files. Typically specified globally in /etc/profile or on a per-user basis in .bashrc files in the hom...

Sudo without password in linux to run a single command

Suppose we needed to allow one user on the system to execute an application that requires sudo without entering a password. In order to do this you need to ...

Setup Unison in CentOS 7

Unison is one of the utilities that is used to replicate files between servers. A big advantage of Unison is its support for master-master replication.

OSSEC client-server installation

OSSEC is an open source attack detection and prevention system. It can be configured to monitor not only events in log files but also changes to files and ru...

Scan Linux server with maldetect

Malware Detect (LMD) is a utility that scans Linux systems for malicious files (malware). Distributed under the GNU GPLv2 license.

Error: xz compression not available

If you get the following message while trying to install any package with yum, it means you picked the wrong repo package during install:

Full Upgrade: NginX 1.9 + PHP7 + MySQL 5.6 on Ubuntu 14.04

Summer’s winding down and my hosting year with amazon is starting over. Decided to spin up a new server with everything on the latest versions.

Disk space issue in Linux

Sometimes there’s plenty of free space on disk, but files stubbornly refuse to get created. In some cases you get an error saying the disk ran out of free sp...

Netstat not found on Fedora

Today, while doing initial setup on a Fedora 20 server, I got this error:

Useful notes about Yum

A cheat sheet for working with the Yum (Yellowdog Updater, Modified) package manager which is used in popular Linux distributions: RedHat, CentOS, Scientific...

Configure SFTP Chroot at Ubuntu 14.04

This article covers setting up an sftp server and isolating users in their home directories (chroot) based on Linux Ubuntu 14.04.

Checking internet connection speed from the Linux console

The speedtest.net site is well known. It helps a lot to check your internet speed, but what about linux servers that don’t have a GUI, only a bash console.

Sorting processes by memory usage in Linux

The following command returns the list of processes using the most memory, in megabytes:

FireWall in CentOS7

In CentOS7 you can no longer edit the usual iptables firewall rules the way you’re used to. iptables itself is still there, but it’s now wrapped in firewalld...

Working with fault-tolerant NFS servers

Using ClamAV (clamscan) on a Linux server

ClamAV is an open source antivirus that allows you to detect trojans, rootkits and other nasty things. Clamscan is a scanning module.

Scan server with Chkrootkit

A rootkit is a hidden type of software. Usually it allows you to hide the existence of certain processes or programs from conventional detection methods or a...

Restoring the root user’s password in Linux

Stuff happens in life, and root passwords get lost. So what do you do when you need into the system and the password is gone? The actual question: how do you...

Mysql-Proxy: Error while loading shared libraries

If you’re reading this note, chances are you followed some random mysql-proxy install guide.

Installing pecl on CentOS 6.5

PECL is a repository of PHP extensions. It gives you access to a catalog of all known extensions, plus tools for downloading and installing PHP extensions.

Installing PostgreSQL 9.4 on Centos 6.5

A note on how to install PostgreSQL 9.4 on Centos 6.5.

Installing the latest version of Python on Centos 6.5

The latest version of Python as of today is 3.4.2. To install the latest python version, first install the required packages:

Install Mysql-Proxy into RedHat 6.4

While working with CentOS I had no issues to install Mysql-Proxy but with RedHad 6.4 this approach didn’t work. Here is why I made a second version on how to...

IpTables NAT in 3 steps

NAT — Network address translation — is a handy feature of any firewall, letting you translate the IP addresses of transit packets.

FFmpeg with libaacplus and fdk-aac support on CentOS

While working on a project for a client I needed to extend ffmpeg’s functionality and add a couple of features it doesn’t have out of the box. Needed to enab...

Setting up replication with lsync

For replicating data between servers, NFS isn’t always the right tool. If you need the same content in two directories across several servers, lsync works we...

Installing Solr + Tomcat6 on CentOS

Solr doesn’t need tomcat to work. You can use its built-in functionality to run it on port 8983.

What LVM is and what it’s for

LVM - logical volume manager. It lets you combine several physical disks into one logical device and treat that as a single disk.

Mysql-Proxy: installing and configuring on CentOS7

Balancing mysql queries matters if you’re running several mysql servers. If you’ve got master-slave replication set up, it makes sense to spread the load acr...

Backup webiste to Dropbox

The other day I was wondering about the correct backup of several WordPress sites and then uploading them to some free storage. I would like it to be done wi...

Server check for bash shellshock vulnerability

To find out if your server is vulnerable to shellshock, run one of the following commands: curl https://shellshocker.net/shellshock_test.sh | bash

Setting Up a High Availability Cluster With Heartbeat on CentOS

In this note I want to cover using heartbeat with two servers as an example. In this example I have two servers running mysql. Sites connect to ip address 19...

Debian clone, or how to make a copy of an existing Debian install

I needed to install the system on about two dozen computers. Ended up copying an already set-up system, for a few reasons: same system across all the comp...

Can’t add a service to startup on CentOS/RHEL

Ran into this while doing some routine work: couldn’t add a custom service to startup. Figured I’d write a quick note about it.

Removing an application and its dependencies on CentOS/RHEL

By default yum remove only removes the package you specify. To also remove everything that got installed along with it, use the yum-plugin-remove-with-leaves...

Copying a Parallels Virtuozzo container to a new hypervisor

In this note I want to cover how to copy/migrate a Parallels Virtuozzo container to KVM/VMware ESX/VirtualBox.

Converting a Parallels Virtuozzo container into a Parallels Bare Metal Server VM

Virtuozzo and Bare Metal Server are two commercial virtualization products from Parallels. They use different approaches to storing VM data.

Writing an image to a flash drive from the command line

Sometimes you need to make a bootable flash drive from an OS distro image or something else.

Installing php-mcrypt on CentOS 6

To install php-mcrypt on CentOS Linux you need to enable a couple extra repos first:

Installing Ruby 1.9.3 on RedHat 6

Ruby 1.9 isn’t available through yum on Red Hat Enterprise Linux 6, per this page: https://access.redhat.com/site/solutions/131923

Listing installed packages in Linux

You can get the list of installed packages in Ubuntu Linux with this command:

Using a custom ssh port for rsync

Rsync is a handy tool for syncing data between servers.

Setting up an NFS server and its clients on CentOS

NFS is quite handy when you have several servers and need shared access to the same storage from each of them. NFS lets you expose folders and files over the...

Fail2Ban configuration

Fail2Ban is a software written in Python which is designed to prevent attacks on the server. It reads ssh, ftp, apache log files and blocks ip addresses by a...

Security tunning of SSH server

SSH is a secure terminal server (secure shell) that provides remote access to the linux system. Why safe? Because all traffic between the client and the serv...

A tale of installing OpenSSH 6 from source on a remote CentOS 5.8 server

Everyone knows how conservative RedHat and CentOS are about updating packages. But new security holes keep turning up in old software versions, and that’s no...

A problem starting Squid

I hit a problem with starting Squid on RedHat Linux v.6.4. Squid just did not start.

Configure SELinux for Apache on CentOS

SELinux is a Linux kernel module that provides an additional mechanism to determine folder and file permissions. Sometimes it creates considerable problems w...

Install Apache mod_evasive.

Description Mod_evasive, formerly known as mod_dosevasive, helps to safeguard your Apache web server against DoS, DDoS (Distributed Denial of Service), and b...

Switching PHP to CGI mode for a specific folder.

Recently, I came across an issue: phpMyAdmin was complaining about the absence of the mcrypt module in PHP. The strange thing was that when I ran php -m in t...

Securing Weak Points in Apache SSL Configuration

Vulnerabilities are occasionally found in the SSL protocol, which enables encrypted traffic exchange between a server and a client. These vulnerabilities pot...

Install modsecurity for Apache

ModSecurity is a kind of firewall for Apache, Nginx and IIS. This is a module that provides a set of rules for filtering traffic. This is a ‘must have’ modul...

Upgrading Apache 2.2.31 OpenSSL 1.0.1q on CentOS 6.7

In recent times, I’ve increasingly encountered the need to update OpenSSL to its latest version on servers. Unfortunately, so much relies on the OpenSSL libr...

Configure suexec for Apache2 on Ubuntu 14.04

The suexec mechanism allows you to execute CGI scripts on behalf of different system users. In this article, I’ll walk through an example of setting up suexe...

Use mod_substitute in Apache

The essence mod_substitute is to replace the text in the body of the response from the web server. With it you can change for example links to one domain wit...

Enabling geodata support in Apache, or building mod_geoip from source

While working on a WHM server I ran into the following problem installing mod_geoip:

Configure Apache for Python 3.4 on CentOS 6.5

To install the latest version of Python 3.4 on CentOS 6.5, you can use the previous article.

Daily statistics in AwStats

AwStats is a log file parser written in perl, with which you can keep statistics of site visits based on information from log files. As a rule, awstats disp...

How to restrict allowed http methods in Apache

The following construction allows you to disable all http request methods in Apache, except for GET, POST and HEAD:

How to deny access to specific folders on a server in Apache

You can deny access to certain folders using the following construction. You can add it in the Apache virtual host settings, httpd.conf or create a separate ...

Configure website in Apache2

The following example contains the Apache2 server configuration file for the tech-notes.net site:

Forward requests over Apache with ProxyPass

For various reasons you may want to display information from one server to another. I won’t go into the reasons.

Install Apache Passenger for Ruby

A small note on how to install Apache passenger on CentOS to work with Ruby. I assume you have the following packages installed: ruby-mysql rubygems r...

Simulate https (ssl) session using the rewrite module

In this article I want to touch on the topic of load balancing https connections.

Load Balancing with Apache

Greetings dear reader. In this article I want to describe how to configure Apache to load balance multiple back-end servers. You’ll need the following two mo...

Problem uploading files over php forms in Apache

Today I encountered the problem of uploading files that clearly do not exceed the post_max_size and upload_max_filesize limits. The following error appears: ...

Building a secure web server

To create the most secure web server we need the following: Create a sandbox chroot with debootstrap sandbox apache2, php5, mysql install and configur...

Brief description of Apache mod_rewrite directives

A brief educational program about the directives that mod_rewrite provides

.htaccess tips and tricks

I’d like to present a set of interesting and not very features of .htaccess files and what can be done with them. Most of what is described here falls into t...

Magento: remove trailing slash from the website URL

A note on how to remove the slash at the end of the URL without damaging the store.

OSSEC client-server installation

OSSEC is an open source attack detection and prevention system. It can be configured to monitor not only events in log files but also changes to files and ru...

Configure SELinux for Apache on CentOS

SELinux is a Linux kernel module that provides an additional mechanism to determine folder and file permissions. Sometimes it creates considerable problems w...

Scan Linux server with maldetect

Malware Detect (LMD) is a utility that scans Linux systems for malicious files (malware). Distributed under the GNU GPLv2 license.

Scan server with Lynis

Lynis (formerly RkHunter) is a security auditing tool for Linux and BSD systems. It performs a detailed audit of many aspects of your system’s security and c...

Install modsecurity for Apache

ModSecurity is a kind of firewall for Apache, Nginx and IIS. This is a module that provides a set of rules for filtering traffic. This is a ‘must have’ modul...

Recover compromized Linux server

If you are reading this article than your site has been hacked. You have seen that spam is being sent from your server and you can’t figure out what to do wi...

How to find the script that is spamming via postfix

If you find that your postfix server keeps sending and you understand that you have been scammed. Pretty disgusting state of affairs.

Using ClamAV (clamscan) on a Linux server

ClamAV is an open source antivirus that allows you to detect trojans, rootkits and other nasty things. Clamscan is a scanning module.

Scan server with Chkrootkit

A rootkit is a hidden type of software. Usually it allows you to hide the existence of certain processes or programs from conventional detection methods or a...

Server check for bash shellshock vulnerability

To find out if your server is vulnerable to shellshock, run one of the following commands: curl https://shellshocker.net/shellshock_test.sh | bash

Configuring Basic Authentication in Nginx

I will consider an example of setting up basic authorization in Nginx for a WordPress site. I need the authorization window to pop up for the following pages...

Create SSL certificate in Linux.

In continuation of the series of articles about SSL I would like to describe the steps for the appearance of certificates. I will not repeat the terminology....

How to restrict allowed http methods in Apache

The following construction allows you to disable all http request methods in Apache, except for GET, POST and HEAD:

How to deny access to specific folders on a server in Apache

You can deny access to certain folders using the following construction. You can add it in the Apache virtual host settings, httpd.conf or create a separate ...

Install modsecurity for Nginx

ModSecurity is a kind of firewall for Apache, Nginx and IIS. This is a module that provides a set of rules for filtering traffic. This is a must have module ...

Configure ClamAV to scan files uploaded via FTP (PureFTPd)

In this note I want to tell you how to configure the ClamAV antivirus to scan files that are uploaded to the server via PureFTPD.

Building a secure web server

To create the most secure web server we need the following: Create a sandbox chroot with debootstrap sandbox apache2, php5, mysql install and configur...

clamav update on Linux Fedora v.10

I got the folllwoing message in Fedora Linux while running freshclam:

What is SSL and how it works

Configuring Postfix Mail Forwarding Domains

Introduction Configuring Postfix mail forwarding domains is a practical solution for situations where local mailboxes are not available, and the server is no...

Postfix change sender domain

Out of the box postfix is sending emails using the domain name that is returned by the following command in the linux shell: uname -n

How to configure Exim to use SendGrid to send mail

I continue my series of articles about email services until the inspiration from the recently solved problems wears off.

Use DKIM signature for outgoing emails

Email spoofing is the creation of email messages with a forged sender address. There are many services that provide protection from spoofing.

Working with the mail queue in Qmail

Qmail is not the last word in mail delivery technology, but this smtp daemon is still very widespread. In particular many servers with the Plesk panel use ex...

Configuring Postfix to send mail through MailGun

This article is about how to configure your Linux server to send mail through the MailGun service.

Blocking mail deletion in Dovecot from the mail client

An interesting task came up. I needed to make it so that even if the user has “delete messages from the server” set in the mail software - the messages still...

Installing and configuring Postfix

This article opens a series of articles about setting up a mail server. The whole story starts with the configuration of the so called mail transfer agent (M...

Installing and configuring an imap/pop3 service based on Dovecot

This is the second article of the series about a mail server based on CentOS Linux. It is about how to give people access to their incoming mail over imap/po...

Installing PostfixAdmin and RoundCube

This note tells how to install the mailbox management tool - PostfixAdmin, and a convenient interface for reading mail - RoundCube, on a server running CentO...

Configuring parallel mail delivery (Dual Delivery) in Postfix

This note tells how to use Postfix to organize parallel delivery of mail to several mail servers within one domain name, without the well known forwarding or...

Moving mail from one server to another with Larch

Larch is a utility written in ruby that can be very useful when moving mail from one mail service to another.

Postfix: change the sender address

If your server sends out mail and you don’t want the messages to be delivered from [email protected], then you can change the sender address.

Sending mail with telnet to an smtp server

Telnet is a nice utility that lets you open a network connection to any service by specifying the port to connect to. Telnet is part of the standard set of u...

Moving SmarterStats to a new server

SmarterStats is moved in 5 steps.

Sendmail is not accepting incoming connections

Found the following error in the logs and decided to write a note about it:

Moving SmarterMail to a new server

At any moment, for one reason or another, the question of moving SmarterMail to a new server can come up. The reasons can be different and I am not going to ...

Moving MailEnable to a new server

Using a boilerplate template when creating a new post in WordPress

While working on a new site, we decided to use a single template for publishing posts of a certain type.

Moving a blog between WordPress multisite installations

There are plenty of articles online describing how to move a blog out of multisite into a standalone WordPress.

Visual editor problems in WordPress

Today I ran into a problem on one of the sites I work on.

Importing posts from WordPress into Yii

Riding the wave of the previous post, I decided to play around with Yii and try porting this site, posts and pages included, over to Yii.

Creating a child theme in WordPress

Inspired by an article on Habr, I decided to write my own take on creating a child theme in WordPress, since the Habr one has way too much text and explanati...

AdSense in a dynamic WordPress sidebar

I’ve had an AdSense block sitting in my sidebar for a while now. It only recently occurred to me that the sidebar has a dynamic size (22% of the page body), ...

How to add AdSense to WordPress - functions.php

Following up on the first post, here’s an alternative way to add AdSense to WordPress without plugins.

Add an AdSense block to a WordPress sidebar

Adsense is probably the most common contextual ad service out there. For WordPress there’s a whole bunch of plugins for installing the ad code.

Adding meta tags to WordPress

By default WordPress doesn’t output the tags you set on a post anywhere in the page source. According to this article meta tag support was removed from WordP...

A few useful tricks for the WordPress theme functions file

WordPress is a solid platform, offering reliable development and endless customization. Working with this CMS I picked up a few useful tricks I want to share:

How to edit the Meta widget in WordPress

Whether a site needs user registration is a question that sparks a lot of debate.

Showing phpinfo output on a WordPress page without FTP access to the server

If you’ve run into the same problem I did, welcome. Someone reached out saying everything's gone. No server access, logins and passwords all changed. Need to...

Contact form for WordPress website without additional plugins

There are different plugins that enable contact form for WordPress websites. For some reason none of them worked correctly on my blog. Knowing some basic Wor...

How to find the WordPress version from the command line

You can find the installed WordPress version on the admin dashboard’s front page, but you might not have admin access. In that case run this command: grep wp...

Adding a button to the WordPress TinyMCE editor menu

Yesterday I added spoiler support to the blog, using this article

Internal Zend error wp-cache-base.php

If you’re seeing this error on your WordPress blog:

Out of memory on a WordPress server, or what to do about php memory_limit

Today, logging into the blog admin, I got this error:

IIS, PHP, OpenSource CMS and rabbits

Personally I consider hosting open-source projects on Windows Server a sacrilege, a stupidity and a moral defect. But sometimes there is a project where the ...

Install Nginx from the source code

There are many casess when we need to compile the the sofware from the source code. Nginx is a briliant case when the can’t enable geoip module or mod_securi...

Setting up Nginx + perl-fcgi

Everyone praises Nginx for its performance. But nobody accounts for the fact that it’s so fast because it’s missing all those modules that extend Apache’s fu...

Building NginX v.1.9.10 from source

Installing any software by compiling the package from source is the best way to get the latest versions.

NginX and X-Forwarded-Proto:HTTPS behind a load balancer

A quick note about https traffic behind crooked load balancers. We have Setting up Nginx + php-fcgi behind a load balancer. A load balancer is like a woman -...

Getting HTTPS client IP addresses from HAProxy (frontend) to Nginx (backend) in HTTP and TCP balancing modes

Foreword

Stats for NginX Upstream

When using NginX as a load balancer, the question comes up of how to properly track traffic delivery stats for the servers in the Upstream section.

Using NginX behind a load balancer with correct ip addresses in the logs

If you have Varnish + NginX on the server, every visitor in the NginX logs will show up with the same ip address - 127.0.0.1. There are two options:

Enabling the stats page in NginX

To enable the NginX stats page, add these lines to the nginx.conf config file, or the file where your sites are described. Add them inside the server { ... }...

Changing the log format in NginX

Many know logformat from Apache server config. The same thing exists for Nginx.

Installing Asp.Net on Linux (nginx+mono+xsp)

In this article I’ll show how to set up a simple nginx + Asp.Net combo. By simple I mean that project-specific quirks, user permission separation, high load ...

How to make Search Engine Friendly (SEF) URLs work in Joomla! on Nginx

Search engine friendly (SEF) URLs are the links to the articles of your site in a form that is easy on the eye. They at least partially show what the post on...

Load balancing with NginX

Hello, dear reader. In this article I want to describe how to set up NginX for load balancing across several back-end servers, say Apache.

GeoIP for Nginx

The GeoIP module lets you determine a client’s location based on their IP address. It resolves city, region, country, longitude, latitude, and other info. Ve...

Setting up Nginx + php-fcgi

I assume nginx is already installed. What’s left is to set up php handling. Everything below was done on CentOS Linux. You can repeat the same steps on Linux...

Get Inique IP addresses from Apache access.log

The following can be used to fetch the unique records from apache access.log. This example covers IP addresses of the clients but this example can be used to...

Automatic Website Configuration in Apache

The simple life of simple websites on an Apache server.

Automatic Website Configuration in NginX

The simple life of simple websites on an NginX server.

Using expect in bash scripts

Expect is a wrapper that provides the ability to program the input for interactive programs. Interactive programs are applications that require the input of ...

Bash: Counting Occurrences of a Character in a String

To count the number of occurrences of a character (letter, digit, symbol) in a string in a bash script, you can use grep and wc:

Doing match calculations in BASH with bc

bc is a tool that allows to do inline calculations in bash cli. Eventually bc can’t be used for complicated calculations.

SED Cheat Sheet

Sed is a stream editor on UNIX-like operating systems that is used to filter and transform text.

Optimizing Images for a Website on a Linux Server

Many of us have run into page speed testers complaining about unoptimized images more than once. Many of us have also ignored those warnings and settled for ...

Interesting Bash Programming Tricks

These tricks were described in Google’s internal project “Testing on the Toilet” (handing out flyers in restrooms to remind developers about testing). This p...

What grep Is and How to Use It

The other day, Habr user simpleadmin posted a pretty useful note about grep. From here on, it’s the author’s words:

Bash Script for Backing Up and Restoring All MySQL Databases and Users

This note is about how to quickly dump all MySQL databases into separate files from bash: Backup:

Bash: Extracting the Configuration of a Single Apache Virtual Host

Starting a series of posts with interesting Bash puzzles.

Capitalizing the First Letter of Each Line in Bash Script Output

In this note I want to look at ways to output lists in bash while capitalizing the first letter/character.

Managing Processes in Bash on Linux

To send a running process to the background, you first need to pause it:

The utf8mb4_unicode_ci problem

While restoring a mysql database dump, this error pops up:

Backing up MySQL stored procedures, functions and triggers

MySQL 5 introduced some interesting new features, like stored procedures and triggers. In this short note I’ll show how to back up and restore these using my...

MySQL client error

Today I ran into this error calling the mysql client:

The max_allowed_packet error when restoring a MySQL database

If you’re reading this note, you’ve run into the following error while restoring a MySQL database:

Mysqldump using PHP

I’ve run into this more than once: you need to pull a dump of a large database from hosting, but there’s no remote access to the mysql engine. PhpMyAdmin mig...

Index in MySQL tables

To create a unique index for a MySQL table, run this command:

Displaying database size in MySQL

To find out the size of your databases, use this query:

Changing the engine for MySQL tables from MyISAM to InnoDB

Changing the engine for MySQL tables from MyIsam to InnoDB happens in two steps: Build a query based on the existing data Run the new query.

MySQL: setting up replication

OK. This isn’t an original article. There’s plenty like it on the internet already. I need it so I don’t have to google it every time I need a cheat sheet.

Things you might not know about Insert in MySQL

Anyone who’s worked with MySQL databases in their code has run into the INSERT statement. Turns out not everyone, even experienced developers, knows how to u...

Understanding the performance statistics from MySQL’s SHOW STATUS command

"SHOW STATUS;" in MySQL returns a large amount of technical data you can use to figure out memory usage, cache performance and resource distribution. Here’s ...

Installing NewRelic Plugins with NPI: MySQL Example

Most people know newrelic.com - a service for tracking application state and performance. This service is developing pretty fast and the developers keep expa...

Installing monit on Debian/Ubuntu

Monit — a program for checking the state of services and keeping them running, which can send notifications when something goes wrong. It runs on linux, bsd ...

Server Not Showing Up in NewRelic

This isn’t an article, just a note for the blog of an ordinary tech guy.

Installing Munin on CentOS

Munin is a tool for monitoring network devices with the ability to keep a history of their performance. You can view the performance graphs in a browser.

Uptime in Cacti Monitoring

Cacti does get SNMP-Uptime from devices, but it only shows it on the device’s own page, and once you have more than 100 such devices, opening each page becom...

Writing Custom Check Modules for Nagios Using mysql and apache2 as Examples

Nagios is an open-source client-server platform for monitoring computer systems and networks. It’s built for observing and tracking the state of compute node...

Monitoring Squid with the SqStat Script

I’m sure every sysadmin has had to answer the why is the internet slow question from users, with something like someone hogging the bandwidth downloading end...

Configuring Awstats for Nginx

In this post I want to go over an example of how to get Awstats working correctly with Nginx server log files.

Configuring Awstats for Apache

Awstats is a free log analyzer written in Perl. It lets you build nice visit report graphs for your site based on info from log files.

Quick and Dirty Website Monitoring (bash script)

Because of the nature of my work I deal with a lot of websites. Given the specifics of these projects, I sometimes need to keep an eye on web resource availa...

Enabling geodata support in Apache, or building mod_geoip from source

While working on a WHM server I ran into the following problem installing mod_geoip:

Mcrypt on WHM/cPanel

To enable mcrypt support in WHM you need to use the EasyApache module.

WHM (cPanel): How to Kill a Stuck Transfer

Had to move accounts between servers today. Naturally used the WHM Transfer tool. One of the batches got stuck mid-process. Unfortunately the developers didn...

WHM(cPanel): Failed to create the account

If while using the WHM(cPanel) Transfer tool you get the following error message:

Using cPanel (WHM) to Manage a Cluster

WHM is a decent server management tool. It’s paid, but the developers did a solid job. It’s fairly common to install WHM/cPanel on a single server that holds...

cPanel (WHM): Installing on a Clean Server

First off, a caveat: for installing any control panel it’s recommended to use a clean server. Otherwise the server may break after the panel is installed.

Installing whm/cpanel and Using a Remote MySQL Server

Got a task: install WHM/cPanel on a server. Sounds simple enough, except there are two servers involved: 1 - web server. 2 - MySQL database server.

List of Mailboxes in WHM/cPanel

Bypassing WHM/cPanel Security Questions

Add new php-handler in Plesk

List php modes form command line:

Mail Gets Delivered Through the plesk_virtual Service

By default, when you create an account in Plesk, local mail delivery gets enabled for it. No matter how many times you tell it to route mail according to the...

Tunning fail2ban in Plesk

Plesk allows to tune configuration of almost everything. fail2ban configuration is locates on the page Tools & Settings. Locate the section of IP Address...

How to Get/Change the Plesk Admin Password from the Command Line

When you’re using the Plesk panel, admin and root are different users, and their passwords can differ. So you might have ssh access to the server as root and...

IP Address Pool Error in Plesk

Sometimes when working with Plesk version 10 you get an ip address pool error:

How to Disable php safe_mode in Plesk

First log into Plesk. Go to the subscriptions page and pick the site you need. Then on the Websites&Domains tab expand Advanced Operations and pick Websi...

Plesk: Viewing All Mailboxes on the Server

First connect to mysql: mysql -uadmin -p`cat /etc/psa/.psa.shadow` psa

Installing the Plesk Migration Manager

To install additional Plesk components you can use this utility: /usr/local/psa/admin/bin/autoinstaller

View all FTP accounts created in Plesk on a Linux server via mysql

It happens that the Plesk WebUI becomes unavailable for any reason. Or we have a set of files from the old server and we need to restore all ftp users on the...

Switching PHP to CGI mode for a specific folder.

Recently, I came across an issue: phpMyAdmin was complaining about the absence of the mcrypt module in PHP. The strange thing was that when I ran php -m in t...

Migrating a Site Away from GoogleSites

Today habrahabr user ‘lord Brabazon Vere-de-Vere’ shared his method for migrating a site off GoogleSites onto separate hosting.

Parsing web Pages with php

For this not-so-easy job we’ll use PHP Simple HTML DOM Parser.

Mysqldump using PHP

I’ve run into this more than once: you need to pull a dump of a large database from hosting, but there’s no remote access to the mysql engine. PhpMyAdmin mig...

PHP: Streaming bash Command Output Line-by-Line in the Browser

To fire off a bash command from php code and output the results, you can use shell_exec(), but what if you need to see the whole output in real time as the s...

How to Connect to a Server over ssh from PHP

A small note on how to connect to a remote server from php, run a command and display the results on screen.

Installing ionCube Loader for PHP

ionCube Loader is needed to run paid components on your server that the site relies on. Such components usually have obfuscated code, which makes them unread...

How to Compile php v.5.5.10 from Sources

This note covers how to install the latest version of PHP on your server from source, using PHP 5.5.10 + CentOS 6.5 as an example.

Refresh Jenkins job properties

Refresh Jenkins job properties

Cheatsheet for Groovy to be used in Jenkins pipelines

Cheatsheet for Groovy to be used in Jenkins pipelines

Parrallel stages in Jenkins Groovy pipeline

Parrallel stages in Jenkins Groovy pipeline

Jenkins auth over AWS Cognito

Jenkins auth over AWS Cognito

Copy the Jenkins job

Copy the Jenkins job

Problems with re-login into Jenkins

Today I ran into a problem with re-login in Jenkins. After the session was broken as a result of restarting the Tomcat daemon, I was asked to log in with a n...

Git issues in Jenkins

While connecting a git repository to Jenkins I got the following error:

Running Jenkins in Tomcat6 on CentOS 6.5

A quick note on how to make Jenkins run on a CentOS server and show its web face in Tomcat6.

How to Install Java JRE on Linux Ubuntu

This is about how to install the latest version of Java JRE on Linux Ubuntu.

Converting Outlook PST to Thunderbird Format

If you decided to move from Windows to Linux and ran into the problem of importing mail from Outlook into Thunderbird, keep reading. The following script he...

Package Installation Issues in Ubuntu 12.04

Even though Ubuntu 12.04 shipped with the LTS (long term support) label, looks like that long term is over. A lot of people have already run into problems in...

Installing Asp.Net on Linux (nginx+mono+xsp)

In this article I’ll show how to set up a simple nginx + Asp.Net combo. By simple I mean that project-specific quirks, user permission separation, high load ...

How to Run Multiple Skype Instances in Ubuntu

In this note I want to show how you can run several Skype processes in Linux Ubuntu. I have 2 running - work and personal.

How to Enable Hibernate on Linux Ubuntu

On some laptops, after installing Linux Ubuntu (12.04 LTS in my case), hibernate is disabled. Looks like it’s because such devices aren’t officially supporte...

Launching a Terminal with Multiple Tabs in Linux Ubuntu

A short note on how to launch a terminal with multiple tabs in Linux Ubuntu:

Adding sites to IIS7 from the command line

A quick note on how to create a site in IIS7 from the command line (cmd.exe). It is very handy if you need to create 100+ sites.

Using WebDeploy to move IIS sites between servers

Using WebDeploy makes the task of moving the configs and the content of the sites between Windows servers much easier. WebDeploy is irreplaceable when you wo...

Displaying ServerVariables in IIS

A lot of admins use the phpinfo function to debug the headers the server gets when the site is requested.

Configuring ETags in IIS7

Entity tags (ETags) are the mechanism web servers and browsers use to determine whether an element in the browser cache matches the object on the server.

The list of sites in IIS6

To get the list of sites in IIS6 you need

404 errors in ColdFusion10

After the move from an IIS6+ColdFusion8 server to a server with IIS7+Coldfusion10 I did not enjoy the fact that all the start pages of the sites open for ver...

IIS, PHP, OpenSource CMS and rabbits

Personally I consider hosting open-source projects on Windows Server a sacrilege, a stupidity and a moral defect. But sometimes there is a project where the ...

Creating an administrator Account in OpenX from MySQL

Creating an admin from the admin panel isn’t a hard task. But what do you do if you don’t have access to the admin panel, but you do have access to the mysql...

Fixing MODX Revolution Errors on php v.5.4.13

While deploying MODX Revolution on a server with php v.5.4.13 I ran into a broken admin panel and search.

Meet Django

Django is a web framework written in Python, that provides a basic set of components for building a site. This article is about exactly that. I’ll cover sett...

Magento Got Stuck on Data Reindexing

Someone reached out to me asking to check what’s wrong with their site. Said it wasn’t working.

How I Load Tested Moodle

I got a task: check how many concurrent users a moodle-based site can handle.

Installing Drush by Hand

Drush is a cli for Drupal. In this article I’ll cover how to install it without pear. I won’t go into details on that.

osCommerce Language File Issue

Working with an osCommerce shop, I periodically hit a ‘503 Server Error’.

Thoughts on Clustering: Part 4 - Need More WEB

After a long quiet spell I decided to continue the story about branching out the server lineup. That phrase came out vague. It’ll make sense as we go.

A short overview of what HaProxy can do

HaProxy is a wonderful and very flexible tool for balancing traffic. It has a whole pile of options and configuration variants, and it has its own quirks. It...

Setting Up a High Availability Cluster With Heartbeat on CentOS

In this note I want to cover using heartbeat with two servers as an example. In this example I have two servers running mysql. Sites connect to ip address 19...

Thoughts on Clustering: Part 3 - Varnish Cache

Finally got my thoughts together to continue rambling about how to make life harder for yourself while cutting server load.

Thoughts on Clustering: Part 2 - Serving Static Content

I spent a while thinking about how to continue the series on clusters. In the previous article <a href="http://www.tech-notes.net/notes-about-clusters/" t...

Thoughts on Clustering. Part 1 - The Concept of a Cluster

A cluster means using several servers to run a single, integrated application. Each server in this setup plays its own assigned role. This article starts a s...

Synchronizing Files Between Two Windows Servers

Usually people use robocopy to synchronize files between Windows servers. In principle robocopy handles this task just fine, but only as long as your servers...

How to Get by Without sed in the Windows Command Line

Today I ran into the need to change some text in a hundred files on a server running Windows. In linux these tasks are easily solved with sed and the ‘-i’ fl...

Counting DNS Zones in Windows Server 2008/2012 with Microsoft Jscript

Once I had to automate the process of getting info about the DNS zones sitting on some abstract Windows server. Again it cuts at my brain that I’m writing a ...

The WinSxS Folder in Windows Server

The Windows component store (C:\Windows\winsxs) is used during so-called servicing operations when installing software. These operations include Windows upda...

IIS, PHP, OpenSource CMS and rabbits

Personally I consider hosting open-source projects on Windows Server a sacrilege, a stupidity and a moral defect. But sometimes there is a project where the ...

Certificate verification error in Lftp

Today I encountered the following message while working normally with lftp: ls: Fatal error: Certificate verification: Not trusted

Virtual users in Pure-Ftp

I would like to describe the way how to use virtual users in pure-ftpd.

Using virtual users in Vsftpd

This post will show you how to create virtual users in vsftpd.

Usage of lftp to work with files on ftp server from Linux

lftp is a command line utility that allows you to exchange data with ftp and http servers. lftp has mirroring functionality that allows you to load or recurs...

Configure ClamAV to scan files uploaded via FTP (PureFTPd)

In this note I want to tell you how to configure the ClamAV antivirus to scan files that are uploaded to the server via PureFTPD.

Automating Database Transfers Between MSSQL 2008 Servers

Spitting on Windows server projects again. The other day I ran into a task - needed to move a few hundred databases from one server to another.

Making a Backup of All Databases in MSSQL Server 2008

Sometimes you need to make a one-off backup of all databases (all databases) so you can move them somewhere or gather them in a separate storage location.

Removing Extra Spaces from Strings in Microsoft Jscript

MS Jscript has a ton of functions and methods borrowed from VisualBasic and Microsoft C/C++. Among them is the trim function, which lets you strip extra spac...

List of ColdFusion DataSources Usernames and Passwords

In ColdFusion settings, database connections can be configured in the admin panel under the DataSources section. But what do you do if the passwords for seve...

Passing Data from Windows CMD to Microsoft Jscript

Ran into another one: I need to get a set of data about the server using Microsoft Jscript. Tripping over Windows 2008 Server quirks again. It’s just really ...

How to restore 100 databases from backups in MSSQL

Moving databases between servers means creating a backup copy on the old server and deploying that backup on the new server. With one or two databases there ...

Making a backup of all the databases in MSSQL 2008/2012

To make backup copies of all the databases on your MSSQL 2008/2012 server you can use the following SQL query:

T-SQL cheat sheet - Part 2

A continuation of the first part:

Working around the The server principal already exists message

While moving MSSQL users I got this message:

Connecting Linked Servers on a new MSSQL

I was setting up a second MSSQL server for a client and hit a problem with configuring Linked Servers on it. The first server had two linked MSSQL instances....

How to get the Joomla! version from the command line

You can get the version of the Joomla CMS from the command line if you have no access to the admin panel. Run the following command from the site folder:

Adding an item to the components menu in the Joomla! admin

After a failed update of a plugin, or any other Joomla! component, an unpleasant situation happens - the icon disappears from the menu. You can easily bring ...

How to make Search Engine Friendly (SEF) URLs work in Joomla! on Nginx

Search engine friendly (SEF) URLs are the links to the articles of your site in a form that is easy on the eye. They at least partially show what the post on...

How to create an admin user in Joomla with mysql

Sometimes you badly need to get into the admin panel of the Joomla CMS, but there is no information about the users that were already created. At the same ti...

Enable Epel, Remi, Atrpms in RHEL/CentOS

It’s no secret that CentOS and other RedHat-like systems come with a standard set of repositories. Unfortunately, many required packages are missing.

Installing Solr + Tomcat6 on CentOS

Solr doesn’t need tomcat to work. You can use its built-in functionality to run it on port 8983.

Setting Up a High Availability Cluster With Heartbeat on CentOS

In this note I want to cover using heartbeat with two servers as an example. In this example I have two servers running mysql. Sites connect to ip address 19...

Error: database disk image is malformed

To make yum work again in CentOS after this error:

Getting HTTPS client IP addresses from HAProxy (frontend) to Nginx (backend) in HTTP and TCP balancing modes

Foreword

The HaProxy statistics page

HaProxy provides a convenient tool for showing statistics in real time.

How to configure the log for HaProxy

To enable HaProxy logging edit /etc/sysconfig/rsyslog - bring the only line there to the following form:

HaProxy configuration examples

Following up on the first article, in this one I want to look at a few examples of configuring HaProxy for balancing traffic.

AWS account structure for a startup after Series A

Same story as the GCP version of this note, different cloud: startup closes Series A, and the AWS side is still one root user, one account, prod and the sand...

Start and Stop Ec2 Instances with CloudWatch Event rule and Lambda

This note can be usefull for those of you who needs to hav EC2 instance running during the certain period of time during the day and awoid spending money whe...

Jenkins auth over AWS Cognito

Jenkins auth over AWS Cognito

Amazon CloudFront and the Access-Control-Allow-Origin error

The other day we deployed a Magento shop in the Amazon cloud. Everything would be fine, but the browser console keeps showing the following error:

List items should be accessed using square brackets

This is a note about the following error that is produced by tflint Warning: List items should be accessed using square brackets (terraform_deprecated_index)...

Use gitlab to store terraform state file

This is a short note about the way to configure your GitlabCI to store the Terraform state file. Terraform backend configuration remains pretty simple: terra...

More examples with terraform for and for_each loops

Loops in terraform is not something new. There is a bunch of articles with examples in the internet. However I had a number of cases when I could not find th...

Use bash script as data source in terrafform

I was for a multiple times when I had to extract some data with bash script and next re-use the result in terraform resource provisioning. I’d like to share ...

Disable Diffie-Hellman Modulus vsFTPD

I couldn’t find how to disable Diffie-Hellman encryption in vsFTPD TLS.

Create SSL certificate in Linux.

In continuation of the series of articles about SSL I would like to describe the steps for the appearance of certificates. I will not repeat the terminology....

What is SSL and how it works

Thoughts on Clustering: Part 3 - Varnish Cache

Finally got my thoughts together to continue rambling about how to make life harder for yourself while cutting server load.

Varnish Configuration Review

There are plenty of articles about how to configure Varnish. Let me say right away that there’s no single correct approach to configuration. The more options...

Purging the Varnish cache from the browser with PHP

In this note I want to show how to purge the Varnish cache in an elegant way. The article describes how to delete pages=objects from the cache using their UR...

Undefined subroutine &Symbol::gensym

Today I got the following error while trying to install the Apache2::Reload Perl module through cpan:

Removing Perl modules installed from cpan

The cpan utility will help you install any Perl module. The thing is that cpan downloads the source archives, compiles them and installs them. The problem sh...

Perl Dancer + mysql + memcached

Most of the people writing Perl have heard about the Perl Dancer micro-framework. But did they use it for anything beyond generating a project, writing a ‘He...

Amazon CloudFront and the Access-Control-Allow-Origin error

The other day we deployed a Magento shop in the Amazon cloud. Everything would be fine, but the browser console keeps showing the following error:

RackSpace CloudFiles - uploading files

To upload files into the CloudFiles storage you can use the SDK for PHP. Other programming languages are supported too. The full installation description is ...

RackSpace Cloud API - getting the token and the endpoint

RackSpace is an American hosting provider with several data centers, offering a big number of hosting solutions. One of the products is cloud hosting with it...

Scan server with Lynis

Lynis (formerly RkHunter) is a security auditing tool for Linux and BSD systems. It performs a detailed audit of many aspects of your system’s security and c...

Quickly building an rpm package in CentOS with Checkinstall

To build an RPM package from an application’s source code you need Checkinstall.

Recover compromized Linux server

If you are reading this article than your site has been hacked. You have seen that spam is being sent from your server and you can’t figure out what to do wi...

Find neighbors of the matrix element at the given position

I force myself to learn something but before learning something new I need to memorize what I knew before. So I take python labs at exercism.org.

Skype4py Script for Sending Skype Messages from the Linux Ubuntu Console

A short note on how to make Bash scripts send messages to Skype.

Installing Asp.Net on Linux (nginx+mono+xsp)

In this article I’ll show how to set up a simple nginx + Asp.Net combo. By simple I mean that project-specific quirks, user permission separation, high load ...

Magento: remove trailing slash from the website URL

A note on how to remove the slash at the end of the URL without damaging the store.

Configuring Basic Authentication in Nginx

I will consider an example of setting up basic authorization in Nginx for a WordPress site. I need the authorization window to pop up for the following pages...

Install modsecurity for Nginx

ModSecurity is a kind of firewall for Apache, Nginx and IIS. This is a module that provides a set of rules for filtering traffic. This is a must have module ...

Sorting table rows with jQuery

Let’s say you have the following table on the page and you need to sort it alphabetically:

Simple and lightweight tabs with jQuery

A Habr user called Lzhedmitriy was not happy with the horizontal text tabs he found on the internet. As a result a simple jQuery plugin that does what he nee...

Error not a TTY on docker exec in ansible

One of the ansible playbooks that I was refactoring recently had a multiple shell steps with docker exec in them. After updating to the latest docker the pla...

Run Yii in Docker container locally

In this article I want to tell you what I did to automatically deploy NginX, php-fcgi and install Yii using docker. It can be usefull for local development. ...

RackSpace CloudFiles - uploading files

To upload files into the CloudFiles storage you can use the SDK for PHP. Other programming languages are supported too. The full installation description is ...

RackSpace Cloud API - getting the token and the endpoint

RackSpace is an American hosting provider with several data centers, offering a big number of hosting solutions. One of the products is cloud hosting with it...

Using git-crypt to encrypt sensitive data in your git repository

This is another note of the kind: “I don’t want to google for it next time I need it in few years”

GIT cheatsheet

This is one of the cheetsheets I have at this website. The primary purpose of this one is to collect all usefull commands you might need in your daily work. ...

Displaying database size in PostgreSQL

I already have a note on checking database size in MySQL, here is the same for psql.

psql command line cheat sheet

I switch between MySQL and PostgreSQL often enough that the psql meta-commands never stick in my head. Every time it’s the same five minutes of googling \d v...

Bypassing WHM/cPanel Security Questions

DNS MX record

What is an MX record and what does it stand for?

Magento: remove trailing slash from the website URL

A note on how to remove the slash at the end of the URL without damaging the store.

Moving an ActiveDirectory Domain Controller to a New Server

In this article, I want to describe the process of migrating an ActiveDirectory domain controller from Windows 2003 to Windows Server 2008.

A Useful Little Trick, Using the Browser Console

Some tasks get solved through the browser console (F12), with a pretty good return on effort. Still, whenever I do this, I can’t shake the feeling that I’m j...

Installing Solr + Tomcat6 on CentOS

Solr doesn’t need tomcat to work. You can use its built-in functionality to run it on port 8983.

A short overview of what HaProxy can do

HaProxy is a wonderful and very flexible tool for balancing traffic. It has a whole pile of options and configuration variants, and it has its own quirks. It...

T-SQL Cheat Sheet - Part 1

In this post I put together a basic set of t-sql scripts that give you metadata about MSSQL. If you’ve ever tried getting some of this info through the GUI, ...

Setting up a Linux server for WordPress/Drupal/Joomla

This is a practical guide to setting up a server for maximum performance running one of the blog-oriented CMS platforms: WordPress, Drupal, or Joomla.

How to find the script that is spamming via postfix

If you find that your postfix server keeps sending and you understand that you have been scammed. Pretty disgusting state of affairs.

Puppet - Entry Point

Puppet is a set of utilities written in Ruby that let you manage a large number of servers from one place. It lets you describe the desired state for every s...

Using Loops in the Windows Command Line

After years working in the linux console, it’s really hard to do tasks on windows servers.

Create account in WHM/cPanel from cli

WHM provides a very friendly interface for managing sites, users and databases on the server. Sometimes you have to create several hundreds of accounts for d...

Create account in WHM/cPanel from cli

WHM provides a very friendly interface for managing sites, users and databases on the server. Sometimes you have to create several hundreds of accounts for d...

Vagrant authorization issue when executing kitchen create in Chef

Chef can fail with the following error running kitchen create command if you have Vagrant 1.8.5:

DevOps CoE Best practices

DevOps Center of Exelence (CoE) is a new trend in team work when DevOps team is no longer concentrated on the single project. It is more a service team insid...

Cloudflare: restrict access to your website for a country

Today I woke up and suddenly realised that most of the articles in this blog were written in russian language and the major visitors come from russian-speeki...

GCP organization and folder structure for a startup after Series A

Recently I had a case where a startup closed their Series A and was still running everything out of one GCP project tied to the founder’s personal Google acc...