#!/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 . import ipaddress import jmespath import os from sys import exit from vyos.config import Config from vyos.template import render from vyos.utils.process import cmd from vyos.utils.process import run from vyos import ConfigError from vyos import airbag airbag.enable() nftables_cgnat_config = '/run/nftables-cgnat.nft' class IPOperations: def __init__(self, ip_prefix: str): self.ip_prefix = ip_prefix self.ip_network = ipaddress.ip_network(ip_prefix) if '/' in ip_prefix else None def get_ips_count(self) -> int: """Returns the number of IPs in a prefix or range. Example: % ip = IPOperations('192.0.2.0/30') % ip.get_ips_count() 4 % ip = IPOperations('192.0.2.0-192.0.2.2') % ip.get_ips_count() 3 """ if '-' in self.ip_prefix: start_ip, end_ip = self.ip_prefix.split('-') start_ip = ipaddress.ip_address(start_ip) end_ip = ipaddress.ip_address(end_ip) return int(end_ip) - int(start_ip) + 1 elif '/31' in self.ip_prefix: return 2 elif '/32' in self.ip_prefix: return 1 else: return sum( 1 for _ in [self.ip_network.network_address] + list(self.ip_network.hosts()) + [self.ip_network.broadcast_address] ) def convert_prefix_to_list_ips(self) -> list: """Converts a prefix or IP range to a list of IPs including the network and broadcast addresses. Example: % ip = IPOperations('192.0.2.0/30') % ip.convert_prefix_to_list_ips() ['192.0.2.0', '192.0.2.1', '192.0.2.2', '192.0.2.3'] % % ip = IPOperations('192.0.0.1-192.0.2.5') % ip.convert_prefix_to_list_ips() ['192.0.2.1', '192.0.2.2', '192.0.2.3', '192.0.2.4', '192.0.2.5'] """ if '-' in self.ip_prefix: start_ip, end_ip = self.ip_prefix.split('-') start_ip = ipaddress.ip_address(start_ip) end_ip = ipaddress.ip_address(end_ip) return [ str(ipaddress.ip_address(ip)) for ip in range(int(start_ip), int(end_ip) + 1) ] elif '/31' in self.ip_prefix: return [ str(ip) for ip in [ self.ip_network.network_address, self.ip_network.broadcast_address, ] ] elif '/32' in self.ip_prefix: return [str(self.ip_network.network_address)] else: return [ str(ip) for ip in [self.ip_network.network_address] + list(self.ip_network.hosts()) + [self.ip_network.broadcast_address] ] def generate_port_rules( external_hosts: list, internal_hosts: list, port_count: int, global_port_range: str = '1024-65535', ) -> list: """Generates list of nftables rules for the batch file.""" rules = [] proto_map_elements = [] other_map_elements = [] start_port, end_port = map(int, global_port_range.split('-')) total_possible_ports = (end_port - start_port) + 1 # Calculate the required number of ports per host required_ports_per_host = port_count # Check if there are enough external addresses for all internal hosts if required_ports_per_host * len(internal_hosts) > total_possible_ports * len( external_hosts ): raise ConfigError("Not enough ports available for the specified parameters!") current_port = start_port current_external_index = 0 for internal_host in internal_hosts: external_host = external_hosts[current_external_index] next_end_port = current_port + required_ports_per_host - 1 # If the port range exceeds the end_port, move to the next external host while next_end_port > end_port: current_external_index = (current_external_index + 1) % len(external_hosts) external_host = external_hosts[current_external_index] current_port = start_port next_end_port = current_port + required_ports_per_host - 1 # Ensure the same port is not assigned to the same external host if any( rule.endswith(f'{external_host}:{current_port}-{next_end_port}') for rule in rules ): raise ConfigError("Not enough ports available for the specified parameters") proto_map_elements.append( f'{internal_host} : {external_host} . {current_port}-{next_end_port}' ) other_map_elements.append(f'{internal_host} : {external_host}') current_port = next_end_port + 1 if current_port > end_port: current_port = start_port current_external_index += 1 # Move to the next external host return [proto_map_elements, other_map_elements] def get_config(config=None): if config: conf = config else: conf = Config() base = ['nat', 'cgnat'] config = conf.get_config_dict( base, get_first_key=True, key_mangling=('-', '_'), no_tag_node_value_mangle=True, with_recursive_defaults=True, ) return config def verify(config): # bail out early - looks like removal from running config if not config: return None if 'pool' not in config: raise ConfigError(f'Pool must be defined!') if 'rule' not in config: raise ConfigError(f'Rule must be defined!') # As PoC allow only one rule for CGNAT translations # one internal pool and one external pool if len(config['rule']) > 1: raise ConfigError(f'Only one rule is allowed for translations!') for pool in ('external', 'internal'): if pool not in config['pool']: raise ConfigError(f'{pool} pool must be defined!') for pool_name, pool_config in config['pool'][pool].items(): if 'range' not in pool_config: raise ConfigError( f'Range for "{pool} pool {pool_name}" must be defined!' ) external_pools_query = "keys(pool.external)" external_pools: list = jmespath.search(external_pools_query, config) internal_pools_query = "keys(pool.internal)" internal_pools: list = jmespath.search(internal_pools_query, config) for rule, rule_config in config['rule'].items(): if 'source' not in rule_config: raise ConfigError(f'Rule "{rule}" source pool must be defined!') if 'pool' not in rule_config['source']: raise ConfigError(f'Rule "{rule}" source pool must be defined!') if 'translation' not in rule_config: raise ConfigError(f'Rule "{rule}" translation pool must be defined!') internal_pool = rule_config['source']['pool'] if internal_pool not in internal_pools: raise ConfigError(f'Internal pool "{internal_pool}" does not exist!') external_pool = rule_config['translation']['pool'] if external_pool not in external_pools: raise ConfigError(f'External pool "{external_pool}" does not exist!') def generate(config): if not config: return None # first external pool as we allow only one as PoC ext_pool_name = jmespath.search("rule.*.translation | [0]", config).get('pool') int_pool_name = jmespath.search("rule.*.source | [0]", config).get('pool') ext_query = f'pool.external."{ext_pool_name}".range | keys(@)' int_query = f'pool.internal."{int_pool_name}".range' external_ranges = jmespath.search(ext_query, config) internal_ranges = [jmespath.search(int_query, config)] external_list_count = [] external_list_hosts = [] internal_list_count = [] internal_list_hosts = [] for ext_range in external_ranges: # External hosts count e_count = IPOperations(ext_range).get_ips_count() external_list_count.append(e_count) # External hosts list e_hosts = IPOperations(ext_range).convert_prefix_to_list_ips() external_list_hosts.extend(e_hosts) for int_range in internal_ranges: # Internal hosts count i_count = IPOperations(int_range).get_ips_count() internal_list_count.append(i_count) # Internal hosts list i_hosts = IPOperations(int_range).convert_prefix_to_list_ips() internal_list_hosts.extend(i_hosts) external_host_count = sum(external_list_count) internal_host_count = sum(internal_list_count) ports_per_user = int( jmespath.search(f'pool.external."{ext_pool_name}".per_user_limit.port', config) ) external_port_range: str = jmespath.search( f'pool.external."{ext_pool_name}".external_port_range', config ) proto_maps, other_maps = generate_port_rules( external_list_hosts, internal_list_hosts, ports_per_user, external_port_range ) config['proto_map_elements'] = ', '.join(proto_maps) config['other_map_elements'] = ', '.join(other_maps) render(nftables_cgnat_config, 'firewall/nftables-cgnat.j2', config) # dry-run newly generated configuration tmp = run(f'nft --check --file {nftables_cgnat_config}') if tmp > 0: raise ConfigError('Configuration file errors encountered!') def apply(config): if not config: # Cleanup cgnat cmd('nft delete table ip cgnat') if os.path.isfile(nftables_cgnat_config): os.unlink(nftables_cgnat_config) return None cmd(f'nft --file {nftables_cgnat_config}') if __name__ == '__main__': try: c = get_config() verify(c) generate(c) apply(c) except ConfigError as e: print(e) exit(1)