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#!/usr/bin/env python3
#
# Copyright (C) 2024 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import os
from sys import exit
from vyos.base import Warning
from vyos.config import Config
from vyos.template import render
from vyos.utils.process import call
from vyos import ConfigError
from vyos import airbag
airbag.enable()
config_file = '/run/suricata/suricata.yaml'
rotate_file = '/etc/logrotate.d/suricata'
address_group_defaults = {
'home-net': {'address': ['192.168.0.0/16','10.0.0.0/8','172.16.0.0/12']},
'external-net': {'group': ['!home-net']},
'http-servers': {'group': ['home-net']},
'smtp-servers': {'group': ['home-net']},
'sql-servers': {'group': ['home-net']},
'dns-servers': {'group': ['home-net']},
'telnet-servers': {'group': ['home-net']},
'aim-servers': {'group': ['external-net']},
'dc-servers': {'group': ['home-net']},
'dnp3-server': {'group': ['home-net']},
'modbus-client': {'group': ['home-net']},
'modbus-server': {'group': ['home-net']},
'enip-client': {'group': ['home-net']},
'enip-server': {'group': ['home-net']},
}
port_group_defaults = {
'http-ports': {'port': ['80']},
'shellcode-ports': {'port': ['!80']},
'oracle-ports': {'port': ['1521']},
'ssh-ports': {'port': ['22']},
'dnp3-ports': {'port': ['20000']},
'modbus-ports': {'port': ['502']},
'file-data-ports': {'port': ['110', '143'], 'group': ['http-ports']},
'ftp-ports': {'port': ['21']},
'geneve-ports': {'port': ['6081']},
'vxlan-ports': {'port': ['4789']},
'teredo-ports': {'port': ['3544']},
}
def get_config(config=None):
if config:
conf = config
else:
conf = Config()
base = ['service', 'suricata']
if not conf.exists(base):
return None
suricata = conf.get_config_dict(base,
get_first_key=True,
with_recursive_defaults=True)
# Ensure minimal defaults are present
suricata['address-group'] = address_group_defaults | suricata.get('address-group', {})
suricata['port-group'] = port_group_defaults | suricata.get('port-group', {})
return suricata
# https://en.wikipedia.org/wiki/Topological_sorting#Depth-first_search
def topological_sort(source):
sorted_nodes = []
permanent_marks = set()
temporary_marks = set()
def visit(n, v):
if n in permanent_marks:
return
if n in temporary_marks:
raise ConfigError('At least one cycle exists in the referenced groups')
temporary_marks.add(n)
for m in v.get('group', []):
m = m.lstrip('!')
if m not in source:
raise ConfigError(f'Undefined referenced group "{m}"')
visit(m, source[m])
temporary_marks.remove(n)
permanent_marks.add(n)
sorted_nodes.append((n, v))
while len(permanent_marks) < len(source):
n = next(n for n in source.keys() if n not in permanent_marks)
visit(n, source[n])
return sorted_nodes
def verify(suricata):
if not suricata:
return None
if 'interface' not in suricata:
raise ConfigError('No interfaces configured')
try:
topological_sort(suricata['address-group'])
except (ConfigError,StopIteration) as e:
raise ConfigError(f'Invalid address-group: {e}')
try:
topological_sort(suricata['port-group'])
except (ConfigError,StopIteration) as e:
raise ConfigError(f'Invalid port-group: {e}')
def generate(suricata):
if not suricata:
for file in [config_file, rotate_file]:
if os.path.isfile(file):
os.unlink(file)
return None
# Config-related formatters
def to_var(s:str):
return s.replace('-','_').upper()
def to_val(s:str):
return s.replace('-',':')
def to_ref(s:str):
if s[0] == '!':
return '!$' + to_var(s[1:])
return '$' + to_var(s)
def to_config(kind:str):
def format_group(group):
(name, value) = group
property = [to_val(property) for property in value.get(kind,[])]
group = [to_ref(group) for group in value.get('group',[])]
return (to_var(name), property + group)
return format_group
# Format the address group
suricata['address-group'] = map(to_config('address'),
topological_sort(suricata['address-group']))
# Format the port group
suricata['port-group'] = map(to_config('port'),
topological_sort(suricata['port-group']))
render(config_file, 'ids/suricata.j2', {'suricata': suricata})
render(rotate_file, 'ids/suricata_logrotate.j2', suricata)
return None
def apply(suricata):
systemd_service = 'suricata.service'
if not suricata or 'interface' not in suricata:
# Stop suricata service if removed
call(f'systemctl stop {systemd_service}')
else:
Warning('To fetch the latest rules, use "update suricata"; '
'To periodically fetch the latest rules, '
'use the task scheduler!')
call(f'systemctl restart {systemd_service}')
return None
if __name__ == '__main__':
try:
c = get_config()
verify(c)
generate(c)
apply(c)
except ConfigError as e:
print(e)
exit(1)
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