rt_table123.sh - Easily create a firewall mark for an additional routing table and expose the IP adress(es) of a network interface to the system

rt_table123.sh

#!/bin/bash

FW_MARK="$((RANDOM%2147483646 + 1))"
  if [ "$(ip -4 rule show fwmark ${FW_MARK})" ] || [ "$(ip -6 rule show fwmark ${FW_MARK})" ]; then
    while [ "$(ip -4 rule show fwmark ${FW_MARK})" ] || [ "$(ip -6 rule show fwmark ${FW_MARK})" ]; do
      FW_MARK="$((RANDOM%2147483646 + 1))"
    done
  fi
TABLE="$((RANDOM%2147483396 + 1))"
  if [ ! "$(ip -4 route show table ${TABLE} 2>/dev/null || echo 1)" = "1" ] || [ ! "$(ip -6 route show table ${TABLE} 2>/dev/null || echo 1)" = "1" ]; then
    while [ ! "$(ip route show table ${TABLE} 2>/dev/null || echo 1)" = "1" ] || [ ! "$(ip -6 route show table ${TABLE} 2>/dev/null || echo 1)" = "1" ]; do
      TABLE="$((RANDOM%2147483396 + 1))"
    done
  fi

pause_and_exit() {
echo "Type Q to quit"
read -r EXIT
  if [ ! "${EXIT}" = "Q" ]; then
    pause_and_exit
  else
    sleep 1
  fi
}

echo 'Add IPv6 route? [y = YES]'
read -r IPV6_CHOOSE

echo 'Select your Network Card or press enter for auto-detection:'
ip link show
read -r IFACE
  if [ ! "${IFACE}" ]; then
    IFACE="$(ip route get 8.8.8.8 2>/dev/null | grep 'dev' | awk '{ print $5 }')"
  fi
  if [ ! "${IFACE}" ]; then
    echo "No Internet link was found."
    exit 1
  fi
  if [ "${IPV6_CHOOSE}" = y ]; then
    if [ ! "$(ip -6 address show ${IFACE} | grep 'inet6')" ]; then
      echo 'The selected network interface has IPv6 disabled.'
      exit 1
    fi
  fi

ip -4 route show dev ${IFACE} | grep -v "default" | while read line; do
  ip -4 route add ${line} table ${TABLE} dev ${IFACE}
done
  if [ "${IPV6_CHOOSE}" = "y" ]; then
    ip -6 route show dev ${IFACE} | grep -v "default" | while read line; do
      ip -6 route add ${line} table ${TABLE} dev ${IFACE}
    done
  fi

ip -4 route add blackhole default table ${TABLE} metric 9999
  if [ "$(ip -4 route show dev ${IFACE} | grep "default" | head -n 1)" ]; then
    ip -4 route show default dev ${IFACE} | while read line; do
      ip -4 route add ${line} dev ${IFACE} table ${TABLE} metric 95
    done
  else
    ip route add default table ${TABLE} dev ${IFACE} metric 95
  fi

  if [ "${IPV6_CHOOSE}" = "y" ]; then
    ip -6 route add blackhole default table ${TABLE} metric 9999
      if [ "$(ip -6 route show dev ${IFACE} | grep "default" | head -n 1)" ]; then
        ip -6 route show default dev ${IFACE} | while read line; do
          ip -6 route add ${line} dev ${IFACE} table ${TABLE} metric 95
        done
      else
        ip -6 route add default table ${TABLE} dev ${IFACE} metric 95
      fi
  else
    ip -6 route add blackhole ::/0 table ${TABLE}
  fi

ip -4 rule add fwmark ${FW_MARK} table ${TABLE}
ip -6 rule add fwmark ${FW_MARK} table ${TABLE}

ip -4 address show dev ${IFACE} | grep "scope global" | grep -Po '(?<=inet\s)[^\s]*' | cut -d "/" -f 1 | while read line; do
  ip -4 rule add from ${line} table ${TABLE}
  ip -4 rule add to ${line} table ${TABLE}
done

  if [ "${IPV6_CHOOSE}" = "y" ]; then
    ip -6 address show dev ${IFACE} | grep "scope global" | grep -Po '(?<=inet6\s)[^\s]*' | cut -d "/" -f 1 | while read line; do
      ip -6 rule add from ${line} table ${TABLE}
      ip -6 rule add to ${line} table ${TABLE}
    done
  fi

echo "================================================================================================================="
echo "| Interface is \"${IFACE}\""
echo "| Fwmark is \"${FW_MARK}\" or \"0x$(printf "%x\n" ${FW_MARK})\""
echo "| Table is \"${TABLE}\""
echo "| "
echo "| "
echo "| Endpoint IPs are:"
echo "| "
echo "| IPv4:"
ip -4 address show dev ${IFACE} | grep "scope global" | grep -Po '(?<=inet\s)[^\s]*' | cut -d "/" -f 1 | while read line; do
echo "| ${line}"
done
echo "| "
if [ "${IPV6_CHOOSE}" = "y" ]; then
echo "| IPv6:"
ip -6 address show dev ${IFACE} | grep "scope global" | grep -Po '(?<=inet6\s)[^\s]*' | cut -d "/" -f 1 | while read line; do
echo "| ${line}"
done
echo "| "
fi
echo "================================================================================================================="
echo ""

pause_and_exit

ip -4 route flush table ${TABLE}
ip -4 rule flush table ${TABLE}
ip -6 route flush table ${TABLE}
ip -6 rule flush table ${TABLE}