diff --git a/scripts/i3blocks/bandwidth b/scripts/i3blocks/bandwidth
index d9d3ab2..50215c3 100755
--- a/scripts/i3blocks/bandwidth
+++ b/scripts/i3blocks/bandwidth
@@ -2,6 +2,7 @@
 # Copyright (C) 2012 Stefan Breunig <stefan+measure-net-speed@mathphys.fsk.uni-heidelberg.de>
 # Copyright (C) 2014 kaueraal
 # Copyright (C) 2015 Thiago Perrotta <perrotta dot thiago at poli dot ufrj dot br>
+# Copyright (C) 2019 Jesús E. <heckyel@hyperbola.info>
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -16,15 +17,42 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+# Get custom IN and OUT labels if provided by command line arguments
+while [[ $# -gt 1 ]]; do
+    key="$1"
+    case "$key" in
+        -i|--inlabel)
+            INLABEL="$2"
+            shift;;
+        -o|--outlabel)
+            OUTLABEL="$2"
+            shift;;
+    esac
+    shift
+done
+
+[[ -z "$INLABEL" ]] && INLABEL="IN "
+[[ -z "$OUTLABEL" ]] && OUTLABEL="OUT "
+
 # Use the provided interface, otherwise the device used for the default route.
-if [[ -n $BLOCK_INSTANCE ]]; then
-  INTERFACE=$BLOCK_INSTANCE
-else
-  INTERFACE=$(ip route | awk '/^default/ { print $5 ; exit }')
+if [[ -z $INTERFACE ]] && [[ -n $BLOCK_INSTANCE ]]; then
+    INTERFACE=$BLOCK_INSTANCE
+elif [[ -z $INTERFACE ]]; then
+    # Verify tun, vpn connection
+    if [[ $(ip route | awk '/^default/ { print $5 ; exit }') = "tun0" ]]; then
+        INTERFACE=$(ip route | awk -v i=5 -v j=3 'FNR == i {print $j}')
+    else
+        INTERFACE=$(ip route | awk '/^default/ { print $5 ; exit }')
+    fi
 fi
 
+# Exit if there is no default route
+[[ -z "$INTERFACE" ]] && exit
+
 # Issue #36 compliant.
-if ! [ -e "/sys/class/net/${INTERFACE}/operstate" ] || ! [ "`cat /sys/class/net/${INTERFACE}/operstate`" = "up" ]
+if ! [ -e "/sys/class/net/${INTERFACE}/operstate" ] || \
+        { ! [ "$TREAT_UNKNOWN_AS_UP" = "1" ] &&
+              ! [ "$(cat "/sys/class/net/${INTERFACE}/operstate")" = "up" ]; }
 then
     echo "$INTERFACE down"
     echo "$INTERFACE down"
@@ -33,11 +61,11 @@ then
 fi
 
 # path to store the old results in
-path="/dev/shm/$(basename $0)-${INTERFACE}"
+path="/dev/shm/$(basename "$0")-${INTERFACE}"
 
 # grabbing data for each adapter.
-read rx < "/sys/class/net/${INTERFACE}/statistics/rx_bytes"
-read tx < "/sys/class/net/${INTERFACE}/statistics/tx_bytes"
+read -r rx < "/sys/class/net/${INTERFACE}/statistics/rx_bytes"
+read -r tx < "/sys/class/net/${INTERFACE}/statistics/tx_bytes"
 
 # get time
 time=$(date +%s)
@@ -45,46 +73,46 @@ time=$(date +%s)
 # write current data if file does not exist. Do not exit, this will cause
 # problems if this file is sourced instead of executed as another process.
 if ! [[ -f "${path}" ]]; then
-  echo "${time} ${rx} ${tx}" > "${path}"
-  chmod 0666 "${path}"
+    echo "${time} ${rx} ${tx}" > "${path}"
+    chmod 0666 "${path}"
 fi
 
 # read previous state and update data storage
-read old < "${path}"
+read -r old < "${path}"
 echo "${time} ${rx} ${tx}" > "${path}"
 
 # parse old data and calc time passed
 old=(${old//;/ })
-time_diff=$(( $time - ${old[0]} ))
+time_diff=$(( time - old[0] ))
 
 # sanity check: has a positive amount of time passed
 [[ "${time_diff}" -gt 0 ]] || exit
 
 # calc bytes transferred, and their rate in byte/s
-rx_diff=$(( $rx - ${old[1]} ))
-tx_diff=$(( $tx - ${old[2]} ))
-rx_rate=$(( $rx_diff / $time_diff ))
-tx_rate=$(( $tx_diff / $time_diff ))
+rx_diff=$(( rx - old[1] ))
+tx_diff=$(( tx - old[2] ))
+rx_rate=$(( rx_diff / time_diff ))
+tx_rate=$(( tx_diff / time_diff ))
 
 # shift by 10 bytes to get KiB/s. If the value is larger than
 # 1024^2 = 1048576, then display MiB/s instead
 
 # incoming
-echo -n "IN "
-rx_kib=$(( $rx_rate >> 10 ))
-if [[ "$rx_rate" -gt 1048576 ]]; then
-  printf '%sM' "`echo "scale=1; $rx_kib / 1024" | bc`"
+echo -n "$INLABEL"
+rx_kib=$(( rx_rate >> 10 ))
+if hash bc 2>/dev/null && [[ "$rx_rate" -gt 1048576 ]]; then
+    printf '%sM' "$(echo "scale=1; $rx_kib / 1024" | bc)"
 else
-  echo -n "${rx_kib}K"
+    echo -n "${rx_kib}K"
 fi
 
 echo -n " "
 
 # outgoing
-echo -n "OUT "
-tx_kib=$(( $tx_rate >> 10 ))
-if [[ "$tx_rate" -gt 1048576 ]]; then
-  printf '%sM' "`echo "scale=1; $tx_kib / 1024" | bc`"
+echo -n "$OUTLABEL"
+tx_kib=$(( tx_rate >> 10 ))
+if hash bc 2>/dev/null && [[ "$tx_rate" -gt 1048576 ]]; then
+    printf '%sM\n' "$(echo "scale=1; $tx_kib / 1024" | bc)"
 else
-  echo -n "${tx_kib}K"
+    echo -n "${tx_kib}K"
 fi