Configuraciones de sistema

Configuraciones en distribución Ubuntu.

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Crear y definir usuario con privilegios sudo y conectarse

adduser <user_name>
usermod -aG sudo <user_name>
su <user_name>

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Actualizar sistema e instalar paquetes básicos

sudo apt update && sudo apt upgrade -y
sudo apt install ufw git tmux

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Modificar fichero /etc/ssh/sshd_config para conexiones SSH

PermitRootLogin no
Port 22222
MaxAuthTries 3
MaxSessions 1
PubkeyAuthentication yes
PasswordAuthentication no

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Reestablecer servicio sshd

sudo systemctl restart ssh
sudo systemctl restart sshd

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Habilitar y configurar UFW

sudo ufw enable
sudo ufw default deny incoming
sudo ufw allow 443/tcp
sudo ufw allow 22222/tcp
sudo ufw status verbose

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Instalar repositorios de Kali Linux

• Editar fichero sources.list

sudo nano /etc/apt/sources.list
	deb http://http.kali.org/kali kali-rolling main non-free contrib 
	deb-src http://http.kali.org/kali kali-rolling main non-free contrib

• Agregar clave GPG de repositorios de Kali

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys ED444FF07D8D0BF6

Si se presenta error por claves GPG de Kali ejecutar lo siguiente

• Descargar clave GPG de Kali

wget -q -O - https://archive.kali.org/archive-key.asc | sudo gpg --dearmor -o /etc/apt/keyrings/kali-archive-keyring.gpg

• Editar fichero sources.list

sudo nano /etc/apt/sources.list
	deb [signed-by=/etc/apt/keyrings/kali-archive-keyring.gpg] http://http.kali.org/kali kali-rolling main non-free contrib
	deb-src [signed-by=/etc/apt/keyrings/kali-archive-keyring.gpg] http://http.kali.org/kali kali-rolling main non-free contrib

• Asignar permisos 644 al fichero kali-archive-keyring.gpg de ser necesario

sudo chmod 644 /etc/apt/keyrings/kali-archive-keyring.gpg

• Actualizar repositorios y sistema

sudo apt update

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Solución a error por respuesta fallida de DNS

sudo systemctl disable systemd-resolved
sudo systemctl stop systemd-resolved
sudo rm /etc/resolv.conf

• Crear fichero resolv.conf y agregar direcciones IP de DNS

sudo nano /etc/resolv.conf
	nameserver 8.8.8.8
	nameserver 8.8.4.4
	nameserver 1.1.1.1

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