Add "check_iface-dns.py"

Check to get IP address from interface make sure that one or more DNS entries
point to this IP adress. Use it to check DynDNS services.

Signed-off-by: Sven Velt <sven@velt.de>

check_iface-dns.py

@@ -0,0 +1,92 @@
+#!/usr/bin/python
+
+from monitoringplugin import MonitoringPlugin
+
+import fcntl
+import socket
+import struct
+
+def get_ipv4_address(iface):
+	sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+	return socket.inet_ntoa(fcntl.ioctl(sock.fileno(), 0x8915, struct.pack('256s', iface[:15]))[20:24])
+
+
+plugin = MonitoringPlugin(pluginname='check_iface-dns', tagforstatusline='IFACE-DNS', description='Check interface address vs. DNS', version='0.1')
+
+plugin.add_cmdlineoption('-i', '', 'iface', 'Interface to get IP from', default='lo')
+plugin.add_cmdlineoption('-d', '', 'dns', 'DNS object(s) to check, comma separated list', default='localhost')
+#plugin.add_cmdlineoption('-4', '', 'v4', 'Use IPv4', action='store_true')
+#plugin.add_cmdlineoption('-6', '', 'v6', 'Use IPv6', action='store_true')
+
+plugin.parse_cmdlineoptions()
+
+#if not plugin.options.v4 and not plugin.options.v6:
+#	plugin.options.v4 = True
+#
+#if plugin.options.v4:
+#	plugin.verbose(1, 'Using IPv4')
+#
+#if plugin.options.v6:
+#	plugin.verbose(1, 'Using IPv6')
+
+
+# Get IP from interface
+try:
+	ip_iface = get_ipv4_address(plugin.options.iface)
+except IOError, (errno, strerror):
+	if errno == 19:
+		plugin.back2nagios(2, 'Interface "%s" does not exist!' % plugin.options.iface)
+	elif errno == 99:
+		plugin.back2nagios(2, 'Interface "%s" has no IP!' % plugin.options.iface)
+
+	plugin.back2nagios(2, 'I/O error(%s): %s, interface "%s"' % (errno, strerror, plugin.options.iface))
+
+plugin.verbose(1, 'Found IP "%s" on interface "%s"' % (ip_iface, plugin.options.iface))
+
+# Get IP(s) from DNS
+if not ',' in plugin.options.dns:
+	# Only one DNS object
+	try:
+		ip_dns = socket.gethostbyname(plugin.options.dns)
+	except socket.gaierror:
+		ip_dns = None
+		plugin.back2nagios(1, 'Could not find "%s" in DNS!' % plugin.options.dns)
+
+	if ip_iface == ip_dns:
+		plugin.back2nagios(0, 'Found %s for "%s" in DNS and on interface "%s"' % (ip_dns, plugin.options.dns, plugin.options.iface))
+	else:
+		plugin.back2nagios(2, 'Found %s for "%s" in DNS, but %s for interface "%s"' % (ip_dns, plugin.options.dns, ip_iface, plugin.options.iface))
+
+else:
+	# Multiple DNS objects
+	plugin.add_returncode(0)
+	failed_dns = []
+
+	for dns in plugin.options.dns.split(','):
+		try:
+			ip_dns = socket.gethostbyname(dns)
+		except socket.gaierror:
+			ip_dns = None
+
+		if ip_dns:
+			plugin.verbose(1, 'Found IP "%s" as DNS object "%s"' % (ip_dns, dns))
+		else:
+			plugin.verbose(1, 'Did not find IP for "%s"' % dns)
+
+		if ip_iface != ip_dns:
+			plugin.add_multilineoutput('CRITICAL - "%s" has unexpected IP "%s"' % (dns, ip_dns))
+			failed_dns.append(dns)
+		else:
+			plugin.add_multilineoutput('OK - "%s" resolves to "%s"' % (dns, ip_dns))
+
+		
+	if len(failed_dns) == 0:
+		plugin.add_returncode(0)
+		plugin.add_output('All DNS objects have a correct IP')
+	else:
+		plugin.add_returncode(2)
+		plugin.add_output('Following DNS objects did not resolve as expected: "%s"' % '", "'.join(failed_dns))
+
+	plugin.exit()
+
+