This script must to be installed with cron to check by time if must to block a predefined list of domains

blockdomains.sh

#!/bin/bash

# Thizer Apps ®
# 
# /*** CONFIGURATION ***/
# // Create a folder to save logs
# sudo mkdir -p /var/log/blockdomains
# sudo chmod 777 /var/log/blockdomains -R
# 
# // Add commands to enable/disable block
# vi ~/.bashrc
# alias blockdomains='echo true > /var/log/blockdomains/.isblock && sudo bash /path/to/script/blockdomains.sh'
# alias unblockdomains='echo false > /var/log/blockdomains/.isblock && sudo bash /path/to/script/blockdomains.sh'
# source ~/.bashrc
#
# Add a ROOT cron entry with:
# */5 * * * * /bin/bash /path/to/script/blockdomains.sh >> /var/log/blockdomains/log-`date "+\%d"`-`date "+\%m"`.log 2>&1

# Define the list of sites to be blocked
# domains=("facebook.com" "instagram" "whatsapp.com")
domains=("facebook.com" "instagram")

# Colors
y='\e[33m'     # Yellow
d='\e[39m'     # Default color
bold='\e[1m'   # bold
dbold='\e[21m' # Default bold

# Require root user
user=$(whoami);
if [ "$user" != "root" ]; then
  echo -e "This script requires ${y}sudo${d}"
  exit 1
fi

# Remove all iptables rules
for domain in "${domains[@]}"
do

  # Maybe it's just a name like "instagram" instead of "instagram.com"
  # so we won't have an IP
  ip=$(ping -c 1 $domain 2>&1 | gawk -F'[()]' '/PING/{print $2}')
  if [ -n "$ip" ]; then
    sudo iptables -D OUTPUT -d $domain -j REJECT
  fi

  # Try to unblock by word string
  sudo iptables -D OUTPUT -m string --algo bm --string "$domain" -j REJECT
done

isblock="/var/log/blockdomains/.isblock"

# Check if user have disabled the block
if [ -e "/var/log/blockdomains/.isblock" ] && [ ! -z "$(cat $isblock)" ] && [ "$(cat $isblock)" == "false" ] ; then
  echo -e "Block canceled, try to run '${y}blockdomains${d}' on terminal to enable"
  exit 0;
fi

# With a 'clear' param the script will
# only clear firewall rules
if [ "$1" = "clear" ]; then
  exit 0
fi;

# Depends of dateutils
if [ -z $(command -v dateutils.dtest) ]; then
  echo "Cannot proceed. Please install 'dateutils' to continue"
  exit 1
fi

# actual time
thetime=$(date +%H:%M:%S)

echo -e "---------------------------------------------------"
echo -e "Let's check it out to block/unblock some domains...\n$thetime\n"

# If it's on block time
if
  (dateutils.dtest $thetime --gt '09:00:00' && dateutils.dtest $thetime --lt '12:00:00') ||
  (dateutils.dtest $thetime --gt '14:00:00' && dateutils.dtest $thetime --lt '16:00:00') ||
  (dateutils.dtest $thetime --gt '16:15:00' && dateutils.dtest $thetime --lt '18:00:00')
then
  for domain in "${domains[@]}"
  do

    # Maybe it's just a name like "instagram" instead of "instagram.com"
    # so we won't have an IP
    ip=$(ping -c 1 $domain 2>&1 | gawk -F'[()]' '/PING/{print $2}')
    if [ -n "$ip" ]; then
      sudo iptables -A OUTPUT -d $domain -j REJECT
    fi

    # Try to block by word string
    sudo iptables -A OUTPUT -m string --algo bm --string "$domain" -j REJECT
    echo -e $domain" must be rejected from now"

  done
fi

# Malfeito feito.
echo -e "\n${y}Mischief managed!${d}\n"

Instalação

Veja no topo do arquivo as instruções para instalar o script no seu sistema Linux.

Opções

Os domínios a serem removidos e os horários para isso devem ser configurados
manualmente, ou seja, editando diretamente o arquivo.

Firewall

Este script irá utilizar o IPTABLES para alterar as configurações do firewall e bloquear
acessos. Verifique se isso não é um problema para você. Em todo caso o uso deste
script é por sua conta e risco.