Added dns-down.sh

dns-down.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+
+# Dependencies: curl, openssl, dig
+
+dns_server=1.1.1.1				# DNS server to test query
+dns_port=53					# DNS UDP port (Default is 53)
+gotify_server="https://push.gotify.example"	# Gotify server address (including http:// or https://)
+gotify_api_key="###############"		# Gotify server application token for this script
+
+# To do: Add sanity checks for the configuration variables
+#        Stateful notifications (only send one notification when it goes down, one when it comes backup up, and reminders every x hours)
+#        Log notification push errors to ~/.offline_error and print them at login with .bashrc
+
+
+# First argument is the message to be pushed, second argument is the message priority (integer from 0 to 10, 0 being low priority and 10 being high)
+gotify_send () {
+  if [ "$2" -ge 0 ] && [ "$2" -le 10 ]; then # Message priority integer sanity check. Default to 5 on failure.
+    priority=$2
+  else
+    >&2 echo "\"$2\" isn't a valid priority. Defaulting priority to 5."
+    priority=5
+  fi
+  curl -s -X POST "$gotify_server/message?token=$gotify_api_key" -F "title=Message from: $HOSTNAME" -F "message=$1" -F "priority=$priority"
+  return $?
+}
+
+
+if dig @$dns_server -p $dns_port google.com > /dev/null ; then # Default timeout is 5 seconds
+  exit 0
+else
+  gotify_send "DNS Server $dns_server#$dns_port isn't responding to queries" 4
+  exit 1
+fi