#!/usr/bin/python
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"""
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usage:
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./dhcp_failed_machines.py /var/log/dhcp.log
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You can also run it directly on the gzip'd logs.
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This script basically expects to run from the dhcp machine, as it looks at
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/etc/dhcp/dhcpd.conf to be able to do reverse DNS lookups. It also expects the
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dhcp log to be copied to some local file.
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If you're lucky, there might still be a copy of this script already on the dhcp
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server at /tmp/looky.py.
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"""
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import gzip
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import itertools
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import pprint
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import re
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import sys
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lookups = {}
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with open('/etc/dhcp/dhcpd.conf', 'r') as f:
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for line in f:
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if line.startswith('#'):
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continue
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if line.split() and line.split()[0] == 'host':
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hostconf = list(itertools.takewhile(lambda x: x.strip() != '}', f))
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d = dict([h.strip().split()[-2:] for h in hostconf])
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hostname = d['ddns-hostname'].replace('"', '').replace(';', '')
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lookups[d['fixed-address'].replace(';', '')] = hostname
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offers = {}
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offenders = set()
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restarts = []
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rgx = re.compile(
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r'(?P<command>[A-Z]+) (?:from|on|for) (?P<host>\d+.\d+.\d+.\d+)')
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server_restart_str = 'Internet Systems Consortium'
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def open_file(f):
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if f.endswith('.gz'):
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return gzip.open(f, 'r')
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else:
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return open(f, 'r')
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with open_file(sys.argv[1]) as f:
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for line in f:
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if server_restart_str in line:
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restarts.append(line)
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continue
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m = rgx.search(line)
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if m:
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command = m.group('command')
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host = m.group('host')
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if command == 'DHCPOFFER':
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offers[host] = offers.get(host, 0) + 1
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if offers[host] > 2:
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offenders.add(host)
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if command == 'DHCPREQUEST':
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offers[host] = 0
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if restarts:
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print 'DHCP restarts:\n %s' % ''.join(restarts)
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def lookup(h):
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return lookups.get(h, h)
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hosts = sorted([lookup(h) for h in offenders])
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if len(sys.argv) == 2:
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pprint.pprint(hosts)
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else:
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warning = int(sys.argv[2])
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critical = int(sys.argv[3])
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if len(offenders) > critical:
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print ('DHCP Critical, number of duts with DHCP failure is %d: %s' %
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(len(hosts), ', '.join(hosts)))
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sys.exit(2)
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elif len(offenders) > warning:
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print ('DHCP Warning, number of duts with DHCP failure is %d: %s' %
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(len(hosts), ', '.join(hosts)))
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sys.exit(1)
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else:
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print ('DHCP OK, number of duts with DHCP failure is %d: %s' %
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(len(hosts), ', '.join(hosts)))
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sys.exit(0)
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