check_netconnections: Count network connections on server

Counts network connection for a port, could use TCP and/or UDP and IPv4
and/or IPv6

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

check_netconnections.py

@@ -0,0 +1,82 @@
+#!/usr/bin/python
+
+from monitoringplugin import MonitoringPlugin
+
+import re
+
+plugin = MonitoringPlugin(pluginname='check_netconnections', tagforstatusline='NETCONNS', description='Count network connections', version='0.1')
+
+plugin.add_cmdlineoption('-p', '', 'port', 'port number', default=None)
+plugin.add_cmdlineoption('-t', '--tcp', 'tcp', 'count TCP connections (default)', action='store_true')
+plugin.add_cmdlineoption('-u', '--udp', 'udp', 'count TCP connections', action='store_true')
+plugin.add_cmdlineoption('-4', '', 'v4', 'count IPv4 connections (default)', action='store_true')
+plugin.add_cmdlineoption('-6', '', 'v6', 'count IPv6 connections', action='store_true')
+plugin.add_cmdlineoption('-w', '', 'warn', 'warning thresold', default='20')
+plugin.add_cmdlineoption('-c', '', 'crit', 'warning thresold', default='50')
+
+plugin.parse_cmdlineoptions()
+
+# Need a port number
+if not plugin.options.port:
+	plugin.back2nagios(3, 'No port number specified!')
+else:
+	plugin.options.port = int(plugin.options.port)
+
+
+# Settings defaults
+if not plugin.options.udp and not plugin.options.tcp:
+	plugin.options.tcp = True
+
+if not plugin.options.v4 and not plugin.options.v6:
+	plugin.options.v4 = True
+
+
+# RegExp
+v4match = re.compile('^\s*\d*:\s*([0-9A-Fa-f]{8}):([0-9A-Fa-f]{4})\s+([0-9A-Fa-f]{8}):([0-9A-Fa-f]{4})')
+v6match = re.compile('^\s*\d*:\s*([0-9A-Fa-f]{32}):([0-9A-Fa-f]{4})\s+([0-9A-Fa-f]{32}):([0-9A-Fa-f]{4})')
+
+
+# Prepare
+count = 0
+protos = []
+versions = []
+
+if plugin.options.tcp:
+	protos.append('tcp')
+if plugin.options.udp:
+	protos.append('udp')
+if plugin.options.v4:
+	versions.append('')
+if plugin.options.v6:
+	versions.append('6')
+
+
+# Go!
+for version in versions:
+
+	if version == '6':
+		matcher = v6match
+	else:
+		matcher = v4match
+
+	for proto in protos:
+		filename = '/proc/net/%s%s' % (proto, version)
+		f = file(filename)
+		lines = f.readlines()
+
+		for line in lines:
+			m = matcher.match(line)
+			if m:
+				port = int(m.group(2), 16)
+				if port == plugin.options.port and m.group(3) not in ['00000000','00000000000000000000000000000000']:
+					count += 1
+
+
+returncode = plugin.value_wc_to_returncode(count, plugin.options.warn, plugin.options.crit)
+plugin.add_returncode(returncode)
+
+plugin.add_output('%s network connections on port %s' % (count, plugin.options.port))
+plugin.format_add_performancedata('netconnections', count, '', warn=plugin.options.warn, crit=plugin.options.crit)
+
+plugin.exit()
+