Updates A and/or AAAA DNS records in DNS Master provider of Dynamic DNS. Works on Linux and OS X.

dnsmaster-update.sh

#!/bin/sh

usage() {
    echo "DNS Master DynDNS update script. Updates A and/or AAAA records with public IPs that you have on your interfaces."
    echo "Usage: $0 -h hostname[,hostname…] -u username -p password"
}

if [ $# -eq 0 ]; then usage; exit 1; fi

USERNAME=""
PASSWORD=""
HOSTNAME=""

# Read configuration from parameters
while [ "$1" != "" ]; do
  case $1 in
      -h | --host )     shift
                        HOSTNAME=$1
                        ;;
      -u | --user )     shift
                        USERNAME=$1
                        ;;
      -p | --password ) shift
                        PASSWORD=$1
                        ;;
      --help )          usage
                        exit 0
                        ;;
      * )               usage
                        exit 1
  esac
  shift
done

[ -z $HOSTNAME ] && echo "You should specify hostname(s) in the -h switch" && exit 1
[ -z $USERNAME ] && echo "You should specify username in the -u switch"    && exit 1
[ -z $PASSWORD ] && echo "You should specify password in the -p switch"    && exit 1

# Get the IPs under which we are known in the internets
ipv4=$(curl -4 -s https://ipv4.wtfismyip.com/text)
ipv6=$(curl -6 -s https://ipv6.wtfismyip.com/text)

# Filter those that we really have on our interfaces
if command -v ip >/dev/null 2>&1; then # First try to use ip command as only available in Red Hat 7
  ipv4=$(ip -o -4 addr | grep inet  | grep -E -o "([0-9]{1,3}[\.]){3}[0-9]{1,3}"              | grep $ipv4)
  ipv6=$(ip -o -6 addr | grep inet6 | grep -E -o "(([0-9a-fA-F]{0,4}:){2,7}[0-9a-fA-F]{1,4})" | grep $ipv6)
elif command -v ifconfig >/dev/null 2>&1; then # Try to use ifconfig, it's deprecated but is only choice for OS X
  ipv4=$(ifconfig | grep inet  | grep -E -o "([0-9]{1,3}[\.]){3}[0-9]{1,3}"              | grep $ipv4)
  ipv6=$(ifconfig | grep inet6 | grep -E -o "(([0-9a-fA-F]{0,4}:){2,7}[0-9a-fA-F]{1,4})" | grep $ipv6)
else
  echo "Required either ip or ifconfig command to be available in PATH!" 1>&2
  exit 2
fi

# Build query string
QUERY=""
[ -n "$ipv4" ] && QUERY="${QUERY}&myip=${ipv4}"
[ -n "$ipv6" ] && QUERY="${QUERY}&ipv6=${ipv6}"

# Ask DNS Master to update records
if [ -n "$QUERY" ]; then
  curl -s --basic --user "${USERNAME}:${PASSWORD}" "https://api.nic.ru/dyndns/update?hostname=${HOSTNAME}${QUERY}"
else
  echo "No public addresses found on interfaces!" 1>&2
  exit 3
fi

exit $?