System

Pfsense is a BSD-based software firewall. The product generally has many useful features such as msn or program banning, web content filtering, user restriction, and VPN. Now let’s look at the answer to the question of what is PfSense.

What is Pfsense?

Pfsense is an open-source firewall/router, FreeBSD software distribution. FreeBSD consists of the open-source codes of the Research Unix of AT&T, which is considered to be the ancestor of UNIX. It has a Web interface for configuration. You can easily install it on any computer or server.

We will use the Mikrotik device RB941-2nD model that we will use in this setup. We will proceed by installing Radius Server on Mikrotik RouterOS 6.46.2 version and Windows server 2008.

In the first step, after installing the radius server on Windows server 2008, we will configure it so that the users in the technical section in the environment can access it. Now let’s click on Add Roles under Rollers on the Windows server.

In this article, we will see how to reset the root password of our Linux operating systems. This will be useful if we forget or do not know the password of our operating system.
Of course, we need to be physically next to our server for this process. That’s why we have to care about the physical security of my servers in order not to hack our servers.

1. As a first step, if our system is on, we shut it down and when starting again we press any key of the keyboard and enter our boot options.

What will you need?

Before you begin this guide, you need the following:

• Terminal access

Step 1 – Access the remote server

It is recommended that you use a newly installed free virtual server to prevent you from accidentally performing an incorrect operation.

SSH, Secure Shell means. A protocol used to connect to a remote server/system.

Here is the simple command you should use:

ssh user @ ServerIP

This command  connects you to a server with an sunucuip The IP address and useruser name. Another and simpler way to connect ssh serveripwould be to use it. With this method, the shell will think that you are trying to connect with the same user you are currently logged in to. 

Finding multiple connections to your server over an IP can always be useful. In many cases, when you receive a DDOS attack, you will see multiple connections over an IP. A command that can be very useful, especially in such a case. For example, you want to list IPs that open more than 50 connections on your server. In this case, you can use the following code;

netstat -n --tcp --udp --numeric-hosts | \
grep -v 127.0.0.1 | \
awk '{if (/(tcp|udp)/) { print $5 }}' | \
sed 's/:.*//' | \
sort | \
uniq -c | \
sort -n | \
awk '{if ($1 > 50) {print "Baglanti Sayisi: "$1"\t"$2; }}'

When you execute the command, you receive an output similar to the following; (Of course, if more than 50 connections are available from a single IP)