fev 122019

The Instant Scan depends on the inotify watches system, provided by the Linux Kernel.

Every Linux installation has a specific amount of inotify watches set by default.

If you want to know how many inotify watches your system has, execute the next command:

cat /proc/sys/fs/inotify/max_user_watches

You will need one inotify watch per watched directory. Thus, the more directories on the server, the greater the amount of things that will be needed.

You can increase the number of inotify watches performing the next command:

echo fs.inotify.max_user_watches=999999 | tee -a /etc/sysctl.conf && sysctl -p

Increase the number 999999 as your needings.

fev 112019

On some of our development servers, we run many instances of the Apache httpd web server on the same system. By “many”, I mean 30 or more separate Apache instances, each with its own configuration file and child processes. This is not unusual on DevCamps setups with many developers working on many projects on the same server at the same time, each project having a complete software stack nearly identical to production.

On Red Hat Enterprise Linux 5, with somewhere in the range of 30 to 40 Apache instances on a server, you can run into failures at startup time with this error or another similar one in the error log:

[error] (28)No space left on device: Cannot create SSLMutex

The exact error will depend on what Apache modules you are running. The “space left on device” error does not mean you’ve run out of disk space or free inodes on your filesystem, but that you have run out of SysV IPC semaphores.

You can see what your limits are like this:

# cat /proc/sys/kernel/sem
250 32000 32 128

I typically double those limits by adding this line to /etc/sysctl.conf:

kernel.sem = 500 64000 64 256

That makes sure you’ll get the change at the next boot. To make the change take immediate effect:

# sysctl -p

With those limits I’ve run 100 Apache instances on the same server.

fev 112019

The service “httpd” appears to be down.

OK just to give an update on this thread, so hopefully it helps someone else in the future.

Apologies in advance to any Level 18 Fire Breathing +5 SysAdmins; this is noob stuff :)

The cPanel team examined my server and determined that Apache had ran out of Semaphores.

Each time HTTPD crashed it didn’t release the semaphores and eventually my server ran out (I had 128). The cPanel team kindly cleared down the “locked” semaphores as follows:

Continue reading »

jan 262019

Em algum momento você poderá precisar alterar o IP principal de um servidor utilizando sistema Operacional CentOS e painel cPanel. Apesar de parecer um processo complexo, um usuário com conhecimento básico em comandos shell  e com acesso root poderá realizar sem maiores problemas em poucos passos.

Continue reading »

dez 072018


Vamos começar instalando o apache2 e algumas libs:

 sudo apt-get install apache2 php7.2 libapache2-mod-php7.2
$ sudo apt-get install libapache2-mod-auth-mysql php7.2-mysql
$ sudo apt-get install apache2-prefork-dev

Habilitando os módulos do apache para o redirecionamento e para o proxy pass:

 sudo a2enmod env proxy_ajp proxy_balancer proxy proxy_connect proxy_http rewrite ssl headers

Para desabilitar os mods basta usar:

 sudo a2dismod [nome-dos-módulos]

Agora iremos criar o arquivo na pasta do apache2:

 sudo nano /etc/apache2/sites-available/meuSite

Continue reading »


 Apache2, Clusterweb, ClusterWeb, Debian, Linux, SSL  Comentários desativados em Certbot
nov 072018


Since it doesn’t seem like your operating system has a packaged version of Certbot, you should use our certbot-auto script to get a copy:

wget https://dl.eff.org/certbot-auto
chmod a+x certbot-auto

certbot-auto accepts the same flags as certbot; it installs all of its own dependencies and updates the client code automatically.

Certbot’s DNS plugins which can be used to automate obtaining a wildcard certificate from Let’s Encrypt’s ACMEv2 server are not available for your OS yet. This should change soon but if you don’t want to wait, you can use these plugins now by running Certbot in Docker instead of using the instructions on this page.


Continue reading »

How to Install Let’s Encrypt on Apache2

 Apache2, Clusterweb, ClusterWeb, Debian, Linux, Profissional de TI, Redes, Segurança, Shell Script  Comentários desativados em How to Install Let’s Encrypt on Apache2
nov 052018

Improving your website security through encryption, even on the most basic servers, can increase your visitors’ trust in your site and your ability to run it. Setting up encryption on your web host has generally been complicated and expensive, which often deters administrators whose web applications might not depend on user input. Let’s Encrypt aims to change this by making implementing encryption on any website easier. They are an open and free project that allows obtaining and installing of certificates through simple, automated, commands.

Let's Encrypt Project Logo

Continue reading »

How To Configure Bind as a Caching or Forwarding DNS Server

 CentOS 7 / RHEL 7, Clusterweb, ClusterWeb, Debian, Dns, Leitura Recomendada, Linux, Profissional de TI, Redes, Segurança, Ubuntu  Comentários desativados em How To Configure Bind as a Caching or Forwarding DNS Server
set 272018


DNS, or the Domain Name System, is often a difficult component to get right when learning how to configure websites and servers. While most people will probably choose to use the DNS servers provided by their hosting company or their domain registrar, there are some advantages to creating your own DNS servers.

In this guide, we will discuss how to install and configure the Bind9 DNS server as a caching or forwarding DNS server on Ubuntu 14.04 machines. These two configurations both have advantages when serving networks of machines.

Continue reading »

Spring Boot Secured By Let’s Encrypt

 Clusterweb, ClusterWeb, Debian, Hospedagem, Leitura Recomendada, Linux, Profissional de TI, Redes, Segurança  Comentários desativados em Spring Boot Secured By Let’s Encrypt
set 272018

In this article, we want to know how we can (1) generate a valid certificate for free; (2) configure a Spring Boot app with it; and lastly (3) how to renew it when it expires.

In my previous blog post, we became familiar with configuration of an Spring Boot Application with a self-signed certificate. Self-signed certificates are good for specific purposes such as test and development. But, if one needs to ship his application to production, certificates should be signed by known and legitimate Certificate Authorities (CA).

These types of certificates are usually expensive. If you want to harden your application with TLS, you need to purchase one of them. The price and complex configuration of application servers made a barrier for many web applications to use secure connections.

In the post-Snowden era, no one needs to convince us that having secure connection using HTTPS is a must. There are lots of efforts to increase awareness of developers and IT administrators to employ such technologies for every single website they make. But how?

Let’s Encrypt projects aims at bringing HTTPS to World Wide Web not only for free but also with the simplest way of configuration.

Continue reading »

set 192018

Constantemente surge uma nova tecnologia no ramo de hospedagem de sites, com intuito de melhorar a performance deles. O HD SSD é mais uma dessas novas “técnicas”.

Acredito que você já tenha ouvido falar neste termo, que tanto tem sido usado pelas empresas de hospedagem, e logo surgiu a dúvida o que é hospedagem com HD SSD e quais são suas vantagens e desvantagens?

Preparamos esse post para que você, de forma simples e rápida, descubra o que é a hospedagem com HD SSD bem como seus pontos positivos e negativos. Fique conosco e confira!

Continue reading »

[Tutorial] Criando um VPS – OpenVZ

 CentOS 7 / RHEL 7, Clusterweb, ClusterWeb, Debian, Leitura Recomendada, Linux, Profissional de TI, Redes  Comentários desativados em [Tutorial] Criando um VPS – OpenVZ
set 172018

Vamos lá:

Primeiro quero dizer que nesse tutorial vamos usar o OpenVZ que tem suporte á todos os sistemas de linux!

Download VPS Linux Debian

Digite os seguintes comandos para fazer o download do Debian Linux:

# cd /vz/template/cache

Criar VPS

Continue reading »

set 082018



Linux utiliza um mecanismo de gerencia o as funções de hardware. Este mecanismo conversa com o hardware do computador por uma camada de abstração chamada HAL (Hardware Abstraction Layer), que é parte componente dos subsistemas do Linux.

As ferramentas pm-utils (Power Manager Utils) e systemd (System and Service Manager) fazem parte do conjunto de softwares da freedesktop.org e são as responsáveis por executar a função sleep, que é composto pelas operações SUSPEND, HIBERNATE, HYBRID_SUSPEND e HYBRID_HIBERNATE. Todas tem a função que restaura a volta ao sistema (RESUME|THAW|POST).

Por exemplo, se o usuário fechar a tampa do notebook (LID CLOSE ACTION), o sistema irá executar uma das funções sleep que está configurada para esta ação. Ao abrir a tampa, o sistema irá executar a função de RESUME.
Continue reading »

set 032018

3.6.1 ClamAV


Instalação do pacote anti-vírus ClamAV. Este pode posteriormente ser integrado num sistema de filtragem de emails ou ficheiros.


root@server:~# aptitude install clamav clamav-docs clamav-daemon clamav-freshclam

Para que o ClamAV possa verificar ficheiros compactados, devem ser também instalados alguns pacotes para descompactar ficheiros:

root@server:~# aptitude install arc arj bzip2 cabextract lzop nomarch p7zip pax tnef unrar-free unzip zoo

Se tiver acesso aos repositórios “non-free”, é possível instalar mais alguns pacotes:

root@server:~# aptitude install lha unrar 

Continue reading »