diff --git a/dynb.sh b/dynb.sh
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+#!/usr/bin/env bash
+
+## Copyright (c) 2021 Eduard Veit
+## All rights reserved. This program and the accompanying materials
+## are made available under the terms of the MIT license
+## which accompanies this distribution, and is available at
+## https://opensource.org/licenses/MIT
+
+_version=0.1.0
+
+###################
+## Configuration ##
+###################
+
+_dyn_domain=dyndns.example.com
+
+## service provider could be inwx
+_serviceProvider=inwx
+
+## update method options: domrobot, dyndns
+_update_method=domrobot
+
+## ip mode could be either: 4, 6 or dual for dualstack
+_ip_mode=dual
+
+## If you are using the DomRobot RPC-API enter your credentials for the web interface login here
+## If you are using the DynDNS2 protocol enter your credentials here
+_username=
+_password=
+
+ ## TTL (time to live) minimum allowed value by inwx is 300 (5 minutes)
+TTL=300
+
+## The IP-Check sites (some sites have different urls for v4 and v6)
+## pro tip: use your own ip check server for privacy
+## it could be as simple as that... 
+## create an index.php with <?php echo $_SERVER['REMOTE_ADDR']; ?>
+_ipv4_checker=api64.ipify.org
+_ipv6_checker=api64.ipify.org
+_DNS_checkServer=1.1.1.1
+
+######################################################
+## You don't need to change the following variables ##
+_INWX_JSON_API_URL=https://api.domrobot.com/jsonrpc/
+_new_IPv4=
+_new_IPv6=
+_dns_records=
+_main_domain=
+_has_getopt=
+_is_IPv4_enabled=false
+_is_IPv6_enabled=false
+
+[[ -x $(command -v jq 2> /dev/null) ]] || {
+  echo "This script depends on jq and it is not available." >&2
+  exit 1
+}
+[[ -x $(command -v curl 2> /dev/null) ]] || {
+  echo "This script depends on curl and it is not available." >&2
+  exit 1
+}
+[[ -x $(command -v getopt 2> /dev/null) ]] || {
+  _has_getopt=false
+}
+
+_help_message="$(cat << 'EOF'
+dynb - dynamic DNS update script for bash
+
+Usage
+-------
+dynb [options]
+
+-h, --help                                displays this help message
+-i | --ip-mode [ 4 | 6 | dual ]           updates type A (IPv4) and AAAA (IPv6) records
+-m | --update-method [dyndns | domrobot]  choose if you want to use DynDNS2 or the DomRobot RPC-API
+-s | --service-provider inwx              set your provider in case you are using DynDNS2
+-d | --domain "dyndns.example.com"        set the domain you want to update
+-u | --username "user42"                  depends on your selected update method and your provider
+-p | --password "SuperSecretPassword"     depends on your selected update method and your provider
+
+##### examples #####
+dynb --ip-mode dualstack --update-method domrobot --domain dyndns.example.com --username user42 --password SuperSecretPassword
+dynb --ip-mode dualstack --update-method dyndns --service-provider inwx --domain dyndns.example.com --username user42 --password SuperSecretPassword
+EOF
+)"
+
+# The main domain or another identifier for the zone is required for the updateRecord call
+function getMainDomain() {
+  request=$( echo "{}" | \
+      jq '(.method="'nameserver.list'")' | \
+      jq '(.params.user="'$_username'")' | \
+      jq '(.params.pass="'$_password'")'
+    )
+
+  response=$(curl --silent  \
+      --request POST $_INWX_JSON_API_URL \
+     --header "Content-Type: application/json" \
+     --data "$request" | jq '.resData.domains[] | select(inside(.domain="'"$_dyn_domain"'"))'
+    )
+  _main_domain=$( echo "$response" | jq --raw-output '.domain'  )
+}
+
+function fetchDNSRecords() {
+  request=$( echo "{}" | \
+      jq '(.method="'nameserver.info'")' | \
+      jq '(.params.user="'$_username'")' | \
+      jq '(.params.pass="'$_password'")' | \
+      jq '(.params.domain="'"$_main_domain"'")' | \
+      jq '(.params.name="'"$_dyn_domain"'")'
+    )
+
+  response=$( curl --silent  \
+      --request POST $_INWX_JSON_API_URL \
+     --header "Content-Type: application/json" \
+     --data "$request"
+    )
+
+  _dns_records=$( echo $response | jq '.resData.record[]' )
+}
+
+# requires parameter A or AAAA
+# result to stdout 
+function getRecordID() {
+  echo $_dns_records | jq 'select(.type == "'${1}'") | .id'
+}
+
+# requires parameter A or AAAA
+# result to stdout
+function getDNSIP() {
+  echo $_dns_records | jq --raw-output 'select(.type == "'${1}'") | .content'
+}
+
+# requires parameter
+# 1. param: 4 or 6 for ip version
+# 2. param: IP check server address
+# result to stdout
+function getRemoteIP() {
+  curl --silent --ipv${1} --dns-servers 1.1.1.1 --location ${2}
+}
+
+# requires parameter
+# 1. param: 4 or 6 as ip version
+function updateRecord() {
+  if [[ ${1} == 4 ]]; then
+    ID=$(getRecordID A)
+    IP=$_new_IPv4
+  fi
+  if [[ ${1} == 6 ]]; then
+    ID=$(getRecordID AAAA)
+    IP=$_new_IPv6
+  fi
+  if [[ $IP != "" ]]; then
+  request=$( echo "{}" | \
+      jq '(.method="'nameserver.updateRecord'")' | \
+      jq '(.params.user="'$_username'")' | \
+      jq '(.params.pass="'$_password'")' | \
+      jq '(.params.id="'$ID'")' | \
+      jq '(.params.content="'$IP'")' | \
+      jq '(.params.ttl="'$TTL'")'
+    )
+  response=$(curl --silent  \
+      --request POST $_INWX_JSON_API_URL \
+      --header "Content-Type: application/json" \
+      --data "$request"
+     )
+     echo -e "$(echo "$response" | jq --raw-output '.msg')\n Domain: $_dyn_domain\n new IPv${1}: $IP"
+  fi
+}
+
+# using DynDNS2 protocol
+function dynupdate() {
+  INWX_DYNDNS_UPDATE_URL="https://dyndns.inwx.com/nic/update?"
+  if [[ $_serviceProvider == "inwx" ]]; then
+    dyndns_update_url=$INWX_DYNDNS_UPDATE_URL
+  fi
+  if [[ $_is_IPv4_enabled == true ]] && [[ $_is_IPv6_enabled == true ]]; then
+    dyndns_update_url="${dyndns_update_url}myip=${_new_IPv4}&myipv6=${_new_IPv6}"
+  fi
+  if [[ $_is_IPv4_enabled == true ]] && [[ $_is_IPv6_enabled == false ]]; then
+    dyndns_update_url="${dyndns_update_url}myip=${_new_IPv4}"
+  fi
+  if [[ $_is_IPv4_enabled == false ]] && [[ $_is_IPv6_enabled == true ]]; then
+    dyndns_update_url="${dyndns_update_url}myipv6=${_new_IPv6}"
+  fi
+
+  result=$(curl --silent --user $_username:$_password "${dyndns_update_url}" )
+  case $result in
+    good )
+    echo "The DynDNS update has been executed."
+    return
+    ;;
+    nochg )
+    echo "Nothing has changed, IP addresses are still up to date."
+    return
+    ;;
+    abuse )
+    echo "You are not allowed to run this command more than once in 60 seconds."
+    return
+    ;;
+    badauth ) 
+    echo "Your username and/or password is wrong."
+    return
+    ;;
+    !yours )
+    echo "The domain does not belong to your user account"
+    return
+    ;;
+    notfqdn )
+    echo "Hostname $_dyn_domain is invalid"
+    return
+    ;;
+    nohost )
+    echo "No hostname has been specified"
+    return
+    ;;
+    numhost )
+    echo "Too many hostnames have been specified for this update"
+    return
+    ;;
+    dnserr )
+    echo "There is an internal error in the dyndns update system"
+    return
+    ;;
+  esac
+}
+
+# requires parameter
+# 1. param: 4 or 6 for IP version
+function ipHasChanged() {
+  if [[ ${1} == 4 ]]; then
+    remote_ip=$(getRemoteIP 4 $_ipv4_checker)
+    if [[ $_update_method == domrobot ]]; then
+      dns_ip=$(getDNSIP A)
+    else
+      dns_ip=$(dig @${_DNS_checkServer} in a +short "$_dyn_domain")
+    fi
+  fi
+  if [[ ${1} == 6 ]]; then
+    remote_ip=$(getRemoteIP 6 $_ipv6_checker)
+    if [[ $_update_method == domrobot ]]; then
+      dns_ip=$(getDNSIP AAAA)
+    else
+      dns_ip=$(dig @${_DNS_checkServer} in aaaa +short "$_dyn_domain")
+    fi
+  fi
+
+  if [[ "$remote_ip" == "$dns_ip" ]]; then
+    return 0
+  else
+    if [[ ${1} == 4 ]]; then
+      _new_IPv4=$remote_ip
+      #echo "New IPv4: $_new_IPv4 old was: $dns_ip"
+    else
+      _new_IPv6=$remote_ip
+      #echo "New IPv6: $_new_IPv6 old was: $dns_ip"
+    fi
+    return 1
+  fi
+}
+
+###############
+## arguments ##
+###############
+
+ARGS=
+if [[ $_has_getopt == "" ]] && [[ $(uname) == Linux ]]; then
+  ARGS=$(getopt --options "hvi:,d:,m:,s:,u:,p:" --longoptions "help,version,link,ip-mode:,domain:,update-method:,service-provider:,username:,password:" -- "$@");
+fi
+eval set -- "$ARGS";
+unset ARGS
+
+function processParameters() {
+  while true; do
+    case $1 in
+      -h | --help )
+        echo "$_help_message"
+        exit 0
+        ;;  
+      -v | --version )
+        echo $_version
+        exit 0
+        ;;  
+      --link )
+        ln --verbose --symbolic "$(realpath "$0")" "$HOME/.local/bin/dynb"
+        exit 0
+        ;;
+      -i | --ip-mode )
+        _ip_mode=$2
+        shift 2
+        ;;
+      -d | --domain )
+        _dyn_domain=$2
+        shift 2
+        ;;
+      -m | --update-method )
+        _update_method=$2
+        shift 2
+        ;;
+      -s | --service-provider )
+        _serviceProvider=$2
+        shift 2
+        ;;
+      -u | --username )
+        _username=$2
+        shift 2
+        ;;
+      -p | --password )
+        _password=$2
+        shift 2
+        ;;
+      --)
+        shift
+        break
+    esac
+  done
+}
+
+##################
+## dependencies ##
+##################
+
+function checkDependencies() {
+  [[ -x $(command -v curl 2> /dev/null) ]] || {
+    echo "This script depends on curl and it is not available." >&2
+    exit 1
+  }
+  [[ -x $(command -v jq 2> /dev/null) ]] || {
+    if [[ $_update_method != dyndns* ]]; then
+      echo "This script depends on jq and it is not available." >&2
+      exit 1
+    fi
+  }
+  [[ -x $(command -v getopt 2> /dev/null) ]] || {
+    _has_getopt=false
+  }
+}
+
+##################
+## MAIN section ##
+##################
+
+FILE=$(dirname "$0")/.env
+if test -f "$FILE"; then
+  # shellcheck source=.env
+  # shellcheck disable=SC1091
+  source "$FILE"
+fi
+
+if [[ $_has_getopt == "" ]] && [[ $(uname) == Linux ]]; then
+  processParameters "$@"
+fi
+
+checkDependencies
+
+if [[ $_ip_mode == d* ]]; then
+  _is_IPv4_enabled=true
+  _is_IPv6_enabled=true
+fi
+if [[ $_ip_mode == *4* ]]; then
+  _is_IPv4_enabled=true
+fi
+if [[ $_ip_mode == *6* ]]; then
+  _is_IPv6_enabled=true
+fi
+
+if [[ $_update_method == "domrobot" ]]; then
+  getMainDomain
+  fetchDNSRecords
+  if [[ $_is_IPv4_enabled == true ]]; then
+    ipHasChanged 4
+    if [[ $? == 1 ]]; then
+      updateRecord 4
+    fi
+  fi
+  if [[ $_is_IPv6_enabled == true ]]; then
+    ipHasChanged 6
+    if [[ $? == 1 ]]; then
+      updateRecord 6
+    fi
+  fi
+fi
+
+if [[ $_update_method == "dyndns" ]]; then
+  changed=0
+  if [[ $_is_IPv4_enabled == true ]]; then
+    ipHasChanged 4
+    (( changed += $? ))
+  fi
+  if [[ $_is_IPv6_enabled == true ]]; then
+    ipHasChanged 6
+    (( changed += $? ))
+  fi
+  if [[ $changed -gt 0 ]]; then
+    dynupdate
+  fi
+fi
+
+unset _DNS_checkServer
+unset _dns_records
+unset _dyn_domain
+unset _has_getopt
+unset _help_message
+unset _INWX_JSON_API_URL
+unset _ip_mode
+unset _ipv4_checker
+unset _ipv6_checker
+unset _is_IPv4_enabled
+unset _is_IPv6_enabled
+unset _main_domain
+unset _new_IPv4
+unset _new_IPv6
+unset _password
+unset _username
+unset _serviceProvider
+unset _version
+
+exit 0