ufw-dns

#!/bin/bash
## bash <(curl -Ls https://gist.github.com/pacmac/41651c4f19c4760ebb20b5de0ee0476f/raw/)
## curl -o ufw-dns -L https://gist.github.com/pacmac/41651c4f19c4760ebb20b5de0ee0476f/raw/
## */5 * * * * bash <(curl -s https://gist.github.com/pacmac/41651c4f19c4760ebb20b5de0ee0476f/raw/)

HOSTNAME="$1";

if [ $# -eq 0 ]; then
  echo "Hostname is required";
  exit 0;
fi

LOGDIR="$HOME/.ufw";
LOGFILE=$LOGDIR/$HOSTNAME
if [ ! -d "$LOGDIR" ];then
  mkdir $LOGDIR
fi

function _alert {
  echo "[$HOSTNAME] OLD:$OIP NEW:$CIP $1";
  ufw status | grep $CIP
  exit 0;  
}

CIP=$(dig +short +nocomments $HOSTNAME | tail -1)

if [ ! -f $LOGFILE ]; then
  /usr/sbin/ufw insert 1 allow from $CIP
  echo -n $CIP > $LOGFILE
else
  OIP=$(cat $LOGFILE)
  if [ "$CIP" = "$OIP" ] ; then
    _alert "no change."  
  else
    /usr/sbin/ufw delete allow from $OIP
    /usr/sbin/ufw insert 1 allow from $CIP
    echo -n $CIP > $LOGFILE
    _alert "Updated."
  fi
fi