Install Firefox with Java support in Ubuntu Linux 18.04

Install Firefox with java support Ubuntu 18.0 Installation: First, make sure you have installed the JRE or JDK. For this example I use the JDK installed in the directory: /opt/jdk1.8.0_201 Execute these commands:

  Create a directory of the installation

Download the Firefox, version 50:

Uncompress it

Create the directory .mozilla/plugins […]

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Oracle Linunx Kernel limits

Oracle recommendatios for operating limits /etc/sysctl.conf kernel.sem = 250 32000 100 128 net.ipv4.ip_local_port_range = 9000 65500 net.core.rmem_default = 4194304 net.core.rmem_max = 4194304 net.core.wmem_default = 262144 net.core.wmem_max = 1048576 fs.aio-max-nr = 1048576 fs.file-max = 6815744   Then execute: /sbin/sysctl -p /etc/security/limits.conf oracle soft nproc 2047 oracle hard nproc 16384 oracle soft nofile 1024 oracle hard nofile […]

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net/http: Golang socket: too many open files


  Ulimits are Linux and Unix features that allows limiting how much resources a user uses, such as processes, CPU time, and various types of memory. You can view your shell’s current ulimits with the command ulimit -a. “Too many open files” errors happen when a process needs to open more files than […]

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ERROR: must be superuser or a member of the pg_read_server_files role to COPY from a file without SUPERUSER privileges

When executing the postgres copy command in a terminal, postgres shows the following error:

Solution, without needing to assign the role of SUPERSUSER to the user: 1. Connect to a psql session with the command.

2. Execute the command \COPY as follow:


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postgres install extensions (pgcrypto) without giving the application superuser rights

In this example, I’m going to install the pgcrypto extension to be able to generate UUID data type. Procedure 1. Access as Postgres superuser. By default, it is the postgres user.

2. Access to the database using the super user (postgres).

3. Lista all the databases to identify the database we want to […]

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Iptables by example

Insert rule at a specific position (prepend) To start, figure out which line should be used for the new rule.

#insert at position 9

Add comments to iptables


Block Access To Outgoing IP Address The following rule will block ip address from making any outgoing connection:

To Outgoing […]

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