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nat.py
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#!/usr/bin/env python3
#
# Copyright (C) 2022 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/>.
from vyos.template import is_ip_network
from vyos.utils.dict import dict_search_args
from vyos.template import bracketize_ipv6
def parse_nat_rule(rule_conf, rule_id, nat_type, ipv6=False):
output = []
ip_prefix = 'ip6' if ipv6 else 'ip'
log_prefix = ('DST' if nat_type == 'destination' else 'SRC') + f'-NAT-{rule_id}'
log_suffix = ''
if ipv6:
log_prefix = log_prefix.replace("NAT-", "NAT66-")
ignore_type_addr = False
translation_str = ''
if 'inbound_interface' in rule_conf:
ifname = rule_conf['inbound_interface']
if ifname != 'any':
output.append(f'iifname "{ifname}"')
if 'outbound_interface' in rule_conf:
ifname = rule_conf['outbound_interface']
if ifname != 'any':
output.append(f'oifname "{ifname}"')
if 'protocol' in rule_conf and rule_conf['protocol'] != 'all':
protocol = rule_conf['protocol']
if protocol == 'tcp_udp':
protocol = '{ tcp, udp }'
output.append(f'meta l4proto {protocol}')
if 'packet_type' in rule_conf:
output.append(f'pkttype ' + rule_conf['packet_type'])
if 'exclude' in rule_conf:
translation_str = 'return'
log_suffix = '-EXCL'
elif 'translation' in rule_conf:
addr = dict_search_args(rule_conf, 'translation', 'address')
port = dict_search_args(rule_conf, 'translation', 'port')
if 'redirect' in rule_conf['translation']:
translation_output = [f'redirect']
redirect_port = dict_search_args(rule_conf, 'translation', 'redirect', 'port')
if redirect_port:
translation_output.append(f'to {redirect_port}')
else:
translation_prefix = nat_type[:1]
translation_output = [f'{translation_prefix}nat']
if addr and is_ip_network(addr):
if not ipv6:
map_addr = dict_search_args(rule_conf, nat_type, 'address')
translation_output.append(f'{ip_prefix} prefix to {ip_prefix} {translation_prefix}addr map {{ {map_addr} : {addr} }}')
ignore_type_addr = True
else:
translation_output.append(f'prefix to {addr}')
elif addr == 'masquerade':
if port:
addr = f'{addr} to '
translation_output = [addr]
log_suffix = '-MASQ'
else:
translation_output.append('to')
if addr:
addr = bracketize_ipv6(addr)
translation_output.append(addr)
options = []
addr_mapping = dict_search_args(rule_conf, 'translation', 'options', 'address_mapping')
port_mapping = dict_search_args(rule_conf, 'translation', 'options', 'port_mapping')
if addr_mapping == 'persistent':
options.append('persistent')
if port_mapping and port_mapping != 'none':
options.append(port_mapping)
translation_str = " ".join(translation_output) + (f':{port}' if port else '')
if options:
translation_str += f' {",".join(options)}'
if not ipv6 and 'backend' in rule_conf['load_balance']:
hash_input_items = []
current_prob = 0
nat_map = []
for trans_addr, addr in rule_conf['load_balance']['backend'].items():
item_prob = int(addr['weight'])
upper_limit = current_prob + item_prob - 1
hash_val = str(current_prob) + '-' + str(upper_limit)
element = hash_val + " : " + trans_addr
nat_map.append(element)
current_prob = current_prob + item_prob
elements = ' , '.join(nat_map)
if 'hash' in rule_conf['load_balance'] and 'random' in rule_conf['load_balance']['hash']:
translation_str += ' numgen random mod 100 map ' + '{ ' + f'{elements}' + ' }'
else:
for input_param in rule_conf['load_balance']['hash']:
if input_param == 'source-address':
param = 'ip saddr'
elif input_param == 'destination-address':
param = 'ip daddr'
elif input_param == 'source-port':
prot = rule_conf['protocol']
param = f'{prot} sport'
elif input_param == 'destination-port':
prot = rule_conf['protocol']
param = f'{prot} dport'
hash_input_items.append(param)
hash_input = ' . '.join(hash_input_items)
translation_str += f' jhash ' + f'{hash_input}' + ' mod 100 map ' + '{ ' + f'{elements}' + ' }'
for target in ['source', 'destination']:
if target not in rule_conf:
continue
side_conf = rule_conf[target]
prefix = target[:1]
addr = dict_search_args(side_conf, 'address')
if addr and not (ignore_type_addr and target == nat_type):
operator = ''
if addr[:1] == '!':
operator = '!='
addr = addr[1:]
output.append(f'{ip_prefix} {prefix}addr {operator} {addr}')
addr_prefix = dict_search_args(side_conf, 'prefix')
if addr_prefix and ipv6:
operator = ''
if addr_prefix[:1] == '!':
operator = '!='
addr_prefix = addr[1:]
output.append(f'ip6 {prefix}addr {operator} {addr_prefix}')
port = dict_search_args(side_conf, 'port')
if port:
protocol = rule_conf['protocol']
if protocol == 'tcp_udp':
protocol = 'th'
operator = ''
if port[:1] == '!':
operator = '!='
port = port[1:]
output.append(f'{protocol} {prefix}port {operator} {{ {port} }}')
if 'group' in side_conf:
group = side_conf['group']
if 'address_group' in group and not (ignore_type_addr and target == nat_type):
group_name = group['address_group']
operator = ''
if group_name[0] == '!':
operator = '!='
group_name = group_name[1:]
output.append(f'{ip_prefix} {prefix}addr {operator} @A_{group_name}')
# Generate firewall group domain-group
elif 'domain_group' in group and not (ignore_type_addr and target == nat_type):
group_name = group['domain_group']
operator = ''
if group_name[0] == '!':
operator = '!='
group_name = group_name[1:]
output.append(f'{ip_prefix} {prefix}addr {operator} @D_{group_name}')
elif 'network_group' in group and not (ignore_type_addr and target == nat_type):
group_name = group['network_group']
operator = ''
if group_name[0] == '!':
operator = '!='
group_name = group_name[1:]
output.append(f'{ip_prefix} {prefix}addr {operator} @N_{group_name}')
if 'mac_group' in group:
group_name = group['mac_group']
operator = ''
if group_name[0] == '!':
operator = '!='
group_name = group_name[1:]
output.append(f'ether {prefix}addr {operator} @M_{group_name}')
if 'port_group' in group:
proto = rule_conf['protocol']
group_name = group['port_group']
if proto == 'tcp_udp':
proto = 'th'
operator = ''
if group_name[0] == '!':
operator = '!='
group_name = group_name[1:]
output.append(f'{proto} {prefix}port {operator} @P_{group_name}')
output.append('counter')
if 'log' in rule_conf:
output.append(f'log prefix "[{log_prefix}{log_suffix}]"')
if translation_str:
output.append(translation_str)
output.append(f'comment "{log_prefix}"')
return " ".join(output)
def parse_nat_static_rule(rule_conf, rule_id, nat_type):
output = []
log_prefix = ('STATIC-DST' if nat_type == 'destination' else 'STATIC-SRC') + f'-NAT-{rule_id}'
log_suffix = ''
ignore_type_addr = False
translation_str = ''
if 'inbound_interface' in rule_conf:
ifname = rule_conf['inbound_interface']
ifprefix = 'i' if nat_type == 'destination' else 'o'
if ifname != 'any':
output.append(f'{ifprefix}ifname "{ifname}"')
if 'exclude' in rule_conf:
translation_str = 'return'
log_suffix = '-EXCL'
elif 'translation' in rule_conf:
translation_prefix = nat_type[:1]
translation_output = [f'{translation_prefix}nat']
addr = dict_search_args(rule_conf, 'translation', 'address')
map_addr = dict_search_args(rule_conf, 'destination', 'address')
if nat_type == 'source':
addr, map_addr = map_addr, addr # Swap
if addr and is_ip_network(addr):
translation_output.append(f'ip prefix to ip {translation_prefix}addr map {{ {map_addr} : {addr} }}')
ignore_type_addr = True
elif addr:
translation_output.append(f'to {addr}')
options = []
addr_mapping = dict_search_args(rule_conf, 'translation', 'options', 'address_mapping')
port_mapping = dict_search_args(rule_conf, 'translation', 'options', 'port_mapping')
if addr_mapping == 'persistent':
options.append('persistent')
if port_mapping and port_mapping != 'none':
options.append(port_mapping)
if options:
translation_output.append(",".join(options))
translation_str = " ".join(translation_output)
prefix = nat_type[:1]
addr = dict_search_args(rule_conf, 'translation' if nat_type == 'source' else nat_type, 'address')
if addr and not ignore_type_addr:
output.append(f'ip {prefix}addr {addr}')
output.append('counter')
if translation_str:
output.append(translation_str)
if 'log' in rule_conf:
output.append(f'log prefix "[{log_prefix}{log_suffix}]"')
output.append(f'comment "{log_prefix}"')
return " ".join(output)

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