# -*- coding: utf-8 -*-
#
# Copyright (C) 2010-2016 Red Hat, Inc.
#
# Authors:
# Thomas Woerner <twoerner@redhat.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# 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.path
import copy
from firewall.core.base import SHORTCUTS, DEFAULT_ZONE_TARGET
from firewall.core.prog import runProg
from firewall.core.logger import log
from firewall.functions import tempFile, readfile, splitArgs, check_mac, portStr, \
check_single_address, check_address, normalizeIP6
from firewall import config
from firewall.errors import FirewallError, INVALID_PASSTHROUGH, INVALID_RULE, UNKNOWN_ERROR
from firewall.core.rich import Rich_Accept, Rich_Reject, Rich_Drop, Rich_Mark, \
Rich_Masquerade, Rich_ForwardPort, Rich_IcmpBlock
import string
BUILT_IN_CHAINS = {
"security": [ "INPUT", "OUTPUT", "FORWARD" ],
"raw": [ "PREROUTING", "OUTPUT" ],
"mangle": [ "PREROUTING", "POSTROUTING", "INPUT", "OUTPUT", "FORWARD" ],
"nat": [ "PREROUTING", "POSTROUTING", "OUTPUT" ],
"filter": [ "INPUT", "OUTPUT", "FORWARD" ],
}
DEFAULT_REJECT_TYPE = {
"ipv4": "icmp-host-prohibited",
"ipv6": "icmp6-adm-prohibited",
}
ICMP = {
"ipv4": "icmp",
"ipv6": "ipv6-icmp",
}
# ipv ebtables also uses this
#
def common_reverse_rule(args):
""" Inverse valid rule """
replace_args = {
# Append
"-A": "-D",
"--append": "--delete",
# Insert
"-I": "-D",
"--insert": "--delete",
# New chain
"-N": "-X",
"--new-chain": "--delete-chain",
}
ret_args = args[:]
for arg in replace_args:
try:
idx = ret_args.index(arg)
except Exception:
continue
if arg in [ "-I", "--insert" ]:
# With insert rulenum, then remove it if it is a number
# Opt at position idx, chain at position idx+1, [rulenum] at
# position idx+2
try:
int(ret_args[idx+2])
except Exception:
pass
else:
ret_args.pop(idx+2)
ret_args[idx] = replace_args[arg]
return ret_args
def common_reverse_passthrough(args):
""" Reverse valid passthough rule """
replace_args = {
# Append
"-A": "-D",
"--append": "--delete",
# Insert
"-I": "-D",
"--insert": "--delete",
# New chain
"-N": "-X",
"--new-chain": "--delete-chain",
}
ret_args = args[:]
for x in replace_args:
try:
idx = ret_args.index(x)
except ValueError:
continue
if x in [ "-I", "--insert" ]:
# With insert rulenum, then remove it if it is a number
# Opt at position idx, chain at position idx+1, [rulenum] at
# position idx+2
try:
int(ret_args[idx+2])
except ValueError:
pass
else:
ret_args.pop(idx+2)
ret_args[idx] = replace_args[x]
return ret_args
raise FirewallError(INVALID_PASSTHROUGH,
"no '-A', '-I' or '-N' arg")
# ipv ebtables also uses this
#
def common_check_passthrough(args):
""" Check if passthough rule is valid (only add, insert and new chain
rules are allowed) """
args = set(args)
not_allowed = set(["-C", "--check", # check rule
"-D", "--delete", # delete rule
"-R", "--replace", # replace rule
"-L", "--list", # list rule
"-S", "--list-rules", # print rules
"-F", "--flush", # flush rules
"-Z", "--zero", # zero rules
"-X", "--delete-chain", # delete chain
"-P", "--policy", # policy
"-E", "--rename-chain"]) # rename chain)
# intersection of args and not_allowed is not empty, i.e.
# something from args is not allowed
if len(args & not_allowed) > 0:
raise FirewallError(INVALID_PASSTHROUGH,
"arg '%s' is not allowed" %
list(args & not_allowed)[0])
# args need to contain one of -A, -I, -N
needed = set(["-A", "--append",
"-I", "--insert",
"-N", "--new-chain"])
# empty intersection of args and needed, i.e.
# none from args contains any needed command
if len(args & needed) == 0:
raise FirewallError(INVALID_PASSTHROUGH,
"no '-A', '-I' or '-N' arg")
class ip4tables(object):
ipv = "ipv4"
name = "ip4tables"
zones_supported = True
def __init__(self, fw):
self._fw = fw
self._command = config.COMMANDS[self.ipv]
self._restore_command = config.COMMANDS["%s-restore" % self.ipv]
self.wait_option = self._detect_wait_option()
self.restore_wait_option = self._detect_restore_wait_option()
self.fill_exists()
self.available_tables = []
self.rich_rule_priority_counts = {}
self.zone_source_index_cache = []
self.our_chains = {} # chains created by firewalld
def fill_exists(self):
self.command_exists = os.path.exists(self._command)
self.restore_command_exists = os.path.exists(self._restore_command)
def __run(self, args):
# convert to string list
if self.wait_option and self.wait_option not in args:
_args = [self.wait_option] + ["%s" % item for item in args]
else:
_args = ["%s" % item for item in args]
log.debug2("%s: %s %s", self.__class__, self._command, " ".join(_args))
(status, ret) = runProg(self._command, _args)
if status != 0:
raise ValueError("'%s %s' failed: %s" % (self._command,
" ".join(_args), ret))
return ret
def split_value(self, rules, opts=None):
"""Split values combined with commas for options in opts"""
if opts is None:
return rules
out_rules = [ ]
for rule in rules:
processed = False
for opt in opts:
try:
i = rule.index(opt)
except ValueError:
pass
else:
if len(rule) > i and "," in rule[i+1]:
# For all items in the comma separated list in index
# i of the rule, a new rule is created with a single
# item from this list
processed = True
items = rule[i+1].split(",")
for item in items:
_rule = rule[:]
_rule[i+1] = item
out_rules.append(_rule)
if not processed:
out_rules.append(rule)
return out_rules
def _rule_replace(self, rule, pattern, replacement):
try:
i = rule.index(pattern)
except ValueError:
return False
else:
rule[i:i+1] = replacement
return True
def is_chain_builtin(self, ipv, table, chain):
return table in BUILT_IN_CHAINS and \
chain in BUILT_IN_CHAINS[table]
def build_chain_rules(self, add, table, chain):
rule = [ "-t", table ]
if add:
rule.append("-N")
else:
rule.append("-X")
rule.append(chain)
return [rule]
def build_rule(self, add, table, chain, index, args):
rule = [ "-t", table ]
if add:
rule += [ "-I", chain, str(index) ]
else:
rule += [ "-D", chain ]
rule += args
return rule
def reverse_rule(self, args):
return common_reverse_rule(args)
def check_passthrough(self, args):
common_check_passthrough(args)
def reverse_passthrough(self, args):
return common_reverse_passthrough(args)
def passthrough_parse_table_chain(self, args):
table = "filter"
try:
i = args.index("-t")
except ValueError:
pass
else:
if len(args) >= i+1:
table = args[i+1]
chain = None
for opt in [ "-A", "--append",
"-I", "--insert",
"-N", "--new-chain" ]:
try:
i = args.index(opt)
except ValueError:
pass
else:
if len(args) >= i+1:
chain = args[i+1]
return (table, chain)
def _run_replace_zone_source(self, rule, zone_source_index_cache):
try:
i = rule.index("%%ZONE_SOURCE%%")
rule.pop(i)
zone = rule.pop(i)
if "-m" == rule[4]: # ipset/mac
zone_source = (zone, rule[7]) # (zone, address)
else:
zone_source = (zone, rule[5]) # (zone, address)
except ValueError:
try:
i = rule.index("%%ZONE_INTERFACE%%")
rule.pop(i)
zone_source = None
except ValueError:
return
rule_add = True
if rule[0] in ["-D", "--delete"]:
rule_add = False
if zone_source and not rule_add:
if zone_source in zone_source_index_cache:
zone_source_index_cache.remove(zone_source)
elif rule_add:
if zone_source:
# order source based dispatch by zone name
if zone_source not in zone_source_index_cache:
zone_source_index_cache.append(zone_source)
zone_source_index_cache.sort(key=lambda x: x[0])
index = zone_source_index_cache.index(zone_source)
else:
if self._fw._allow_zone_drifting:
index = 0
else:
index = len(zone_source_index_cache)
rule[0] = "-I"
rule.insert(2, "%d" % (index + 1))
def _set_rule_replace_rich_rule_priority(self, rule, rich_rule_priority_counts):
"""
Change something like
-t filter -I public_IN %%RICH_RULE_PRIORITY%% 123
or
-t filter -A public_IN %%RICH_RULE_PRIORITY%% 321
into
-t filter -I public_IN 4
or
-t filter -I public_IN
"""
try:
i = rule.index("%%RICH_RULE_PRIORITY%%")
except ValueError:
pass
else:
rule_add = True
insert = False
insert_add_index = -1
rule.pop(i)
priority = rule.pop(i)
if type(priority) != int:
raise FirewallError(INVALID_RULE, "rich rule priority must be followed by a number")
table = "filter"
for opt in [ "-t", "--table" ]:
try:
j = rule.index(opt)
except ValueError:
pass
else:
if len(rule) >= j+1:
table = rule[j+1]
for opt in [ "-A", "--append",
"-I", "--insert",
"-D", "--delete" ]:
try:
insert_add_index = rule.index(opt)
except ValueError:
pass
else:
if len(rule) >= insert_add_index+1:
chain = rule[insert_add_index+1]
if opt in [ "-I", "--insert" ]:
insert = True
if opt in [ "-D", "--delete" ]:
rule_add = False
chain = (table, chain)
# Add the rule to the priority counts. We don't need to store the
# rule, just bump the ref count for the priority value.
if not rule_add:
if chain not in rich_rule_priority_counts or \
priority not in rich_rule_priority_counts[chain] or \
rich_rule_priority_counts[chain][priority] <= 0:
raise FirewallError(UNKNOWN_ERROR, "nonexistent or underflow of rich rule priority count")
rich_rule_priority_counts[chain][priority] -= 1
else:
if chain not in rich_rule_priority_counts:
rich_rule_priority_counts[chain] = {}
if priority not in rich_rule_priority_counts[chain]:
rich_rule_priority_counts[chain][priority] = 0
# calculate index of new rule
index = 1
for p in sorted(rich_rule_priority_counts[chain].keys()):
if p == priority and insert:
break
index += rich_rule_priority_counts[chain][p]
if p == priority:
break
rich_rule_priority_counts[chain][priority] += 1
rule[insert_add_index] = "-I"
rule.insert(insert_add_index+2, "%d" % index)
def set_rules(self, rules, log_denied):
temp_file = tempFile()
table_rules = { }
rich_rule_priority_counts = copy.deepcopy(self.rich_rule_priority_counts)
zone_source_index_cache = copy.deepcopy(self.zone_source_index_cache)
for _rule in rules:
rule = _rule[:]
# replace %%REJECT%%
self._rule_replace(rule, "%%REJECT%%", \
["REJECT", "--reject-with", DEFAULT_REJECT_TYPE[self.ipv]])
# replace %%ICMP%%
self._rule_replace(rule, "%%ICMP%%", [ICMP[self.ipv]])
# replace %%LOGTYPE%%
try:
i = rule.index("%%LOGTYPE%%")
except ValueError:
pass
else:
if log_denied == "off":
continue
if log_denied in [ "unicast", "broadcast", "multicast" ]:
rule[i:i+1] = [ "-m", "pkttype", "--pkt-type", log_denied ]
else:
rule.pop(i)
self._set_rule_replace_rich_rule_priority(rule, rich_rule_priority_counts)
self._run_replace_zone_source(rule, zone_source_index_cache)
table = "filter"
# get table form rule
for opt in [ "-t", "--table" ]:
try:
i = rule.index(opt)
except ValueError:
pass
else:
if len(rule) >= i+1:
rule.pop(i)
table = rule.pop(i)
# we can not use joinArgs here, because it would use "'" instead
# of '"' for the start and end of the string, this breaks
# iptables-restore
for i in range(len(rule)):
for c in string.whitespace:
if c in rule[i] and not (rule[i].startswith('"') and
rule[i].endswith('"')):
rule[i] = '"%s"' % rule[i]
table_rules.setdefault(table, []).append(rule)
for table in table_rules:
rules = table_rules[table]
rules = self.split_value(rules, [ "-s", "--source" ])
rules = self.split_value(rules, [ "-d", "--destination" ])
temp_file.write("*%s\n" % table)
for rule in rules:
temp_file.write(" ".join(rule) + "\n")
temp_file.write("COMMIT\n")
temp_file.close()
stat = os.stat(temp_file.name)
log.debug2("%s: %s %s", self.__class__, self._restore_command,
"%s: %d" % (temp_file.name, stat.st_size))
args = [ ]
if self.restore_wait_option:
args.append(self.restore_wait_option)
args.append("-n")
(status, ret) = runProg(self._restore_command, args,
stdin=temp_file.name)
if log.getDebugLogLevel() > 2:
lines = readfile(temp_file.name)
if lines is not None:
i = 1
for line in lines:
log.debug3("%8d: %s" % (i, line), nofmt=1, nl=0)
if not line.endswith("\n"):
log.debug3("", nofmt=1)
i += 1
os.unlink(temp_file.name)
if status != 0:
raise ValueError("'%s %s' failed: %s" % (self._restore_command,
" ".join(args), ret))
self.rich_rule_priority_counts = rich_rule_priority_counts
self.zone_source_index_cache = zone_source_index_cache
def set_rule(self, rule, log_denied):
# replace %%REJECT%%
self._rule_replace(rule, "%%REJECT%%", \
["REJECT", "--reject-with", DEFAULT_REJECT_TYPE[self.ipv]])
# replace %%ICMP%%
self._rule_replace(rule, "%%ICMP%%", [ICMP[self.ipv]])
# replace %%LOGTYPE%%
try:
i = rule.index("%%LOGTYPE%%")
except ValueError:
pass
else:
if log_denied == "off":
return ""
if log_denied in [ "unicast", "broadcast", "multicast" ]:
rule[i:i+1] = [ "-m", "pkttype", "--pkt-type", log_denied ]
else:
rule.pop(i)
rich_rule_priority_counts = copy.deepcopy(self.rich_rule_priority_counts)
zone_source_index_cache = copy.deepcopy(self.zone_source_index_cache)
self._set_rule_replace_rich_rule_priority(rule, rich_rule_priority_counts)
self._run_replace_zone_source(rule, zone_source_index_cache)
output = self.__run(rule)
self.rich_rule_priority_counts = rich_rule_priority_counts
self.zone_source_index_cache = zone_source_index_cache
return output
def get_available_tables(self, table=None):
ret = []
tables = [ table ] if table else BUILT_IN_CHAINS.keys()
for table in tables:
if table in self.available_tables:
ret.append(table)
else:
try:
self.__run(["-t", table, "-L", "-n"])
self.available_tables.append(table)
ret.append(table)
except ValueError:
log.debug1("%s table '%s' does not exist (or not enough permission to check)." % (self.ipv, table))
return ret
def _detect_wait_option(self):
wait_option = ""
ret = runProg(self._command, ["-w", "-L", "-n"]) # since iptables-1.4.20
if ret[0] == 0:
wait_option = "-w" # wait for xtables lock
ret = runProg(self._command, ["-w10", "-L", "-n"]) # since iptables > 1.4.21
if ret[0] == 0:
wait_option = "-w10" # wait max 10 seconds
log.debug2("%s: %s will be using %s option.", self.__class__, self._command, wait_option)
return wait_option
def _detect_restore_wait_option(self):
temp_file = tempFile()
temp_file.write("#foo")
temp_file.close()
wait_option = ""
for test_option in ["-w", "--wait=2"]:
ret = runProg(self._restore_command, [test_option], stdin=temp_file.name)
if ret[0] == 0 and "invalid option" not in ret[1] \
and "unrecognized option" not in ret[1]:
wait_option = test_option
break
log.debug2("%s: %s will be using %s option.", self.__class__, self._restore_command, wait_option)
os.unlink(temp_file.name)
return wait_option
def build_flush_rules(self):
self.rich_rule_priority_counts = {}
self.zone_source_index_cache = []
rules = []
for table in BUILT_IN_CHAINS.keys():
if not self.get_available_tables(table):
continue
# Flush firewall rules: -F
# Delete firewall chains: -X
# Set counter to zero: -Z
for flag in [ "-F", "-X", "-Z" ]:
rules.append(["-t", table, flag])
return rules
def build_set_policy_rules(self, policy):
rules = []
_policy = "DROP" if policy == "PANIC" else policy
for table in BUILT_IN_CHAINS.keys():
if not self.get_available_tables(table):
continue
if table == "nat":
continue
for chain in BUILT_IN_CHAINS[table]:
rules.append(["-t", table, "-P", chain, _policy])
return rules
def supported_icmp_types(self, ipv=None):
"""Return ICMP types that are supported by the iptables/ip6tables command and kernel"""
ret = [ ]
output = ""
try:
output = self.__run(["-p",
"icmp" if self.ipv == "ipv4" else "ipv6-icmp",
"--help"])
except ValueError as ex:
if self.ipv == "ipv4":
log.debug1("iptables error: %s" % ex)
else:
log.debug1("ip6tables error: %s" % ex)
lines = output.splitlines()
in_types = False
for line in lines:
#print(line)
if in_types:
line = line.strip().lower()
splits = line.split()
for split in splits:
if split.startswith("(") and split.endswith(")"):
x = split[1:-1]
else:
x = split
if x not in ret:
ret.append(x)
if self.ipv == "ipv4" and line.startswith("Valid ICMP Types:") or \
self.ipv == "ipv6" and line.startswith("Valid ICMPv6 Types:"):
in_types = True
return ret
def build_default_tables(self):
# nothing to do, they always exist
return []
def build_default_rules(self, log_denied="off"):
default_rules = {}
if self.get_available_tables("security"):
default_rules["security"] = [ ]
self.our_chains["security"] = set()
for chain in BUILT_IN_CHAINS["security"]:
default_rules["security"].append("-N %s_direct" % chain)
default_rules["security"].append("-A %s -j %s_direct" % (chain, chain))
self.our_chains["security"].add("%s_direct" % chain)
if self.get_available_tables("raw"):
default_rules["raw"] = [ ]
self.our_chains["raw"] = set()
for chain in BUILT_IN_CHAINS["raw"]:
default_rules["raw"].append("-N %s_direct" % chain)
default_rules["raw"].append("-A %s -j %s_direct" % (chain, chain))
self.our_chains["raw"].add("%s_direct" % chain)
if chain == "PREROUTING":
for dispatch_suffix in ["ZONES_SOURCE", "ZONES"] if self._fw._allow_zone_drifting else ["ZONES"]:
default_rules["raw"].append("-N %s_%s" % (chain, dispatch_suffix))
default_rules["raw"].append("-A %s -j %s_%s" % (chain, chain, dispatch_suffix))
self.our_chains["raw"].update(set(["%s_%s" % (chain, dispatch_suffix)]))
if self.get_available_tables("mangle"):
default_rules["mangle"] = [ ]
self.our_chains["mangle"] = set()
for chain in BUILT_IN_CHAINS["mangle"]:
default_rules["mangle"].append("-N %s_direct" % chain)
default_rules["mangle"].append("-A %s -j %s_direct" % (chain, chain))
self.our_chains["mangle"].add("%s_direct" % chain)
if chain == "PREROUTING":
for dispatch_suffix in ["ZONES_SOURCE", "ZONES"] if self._fw._allow_zone_drifting else ["ZONES"]:
default_rules["mangle"].append("-N %s_%s" % (chain, dispatch_suffix))
default_rules["mangle"].append("-A %s -j %s_%s" % (chain, chain, dispatch_suffix))
self.our_chains["mangle"].update(set(["%s_%s" % (chain, dispatch_suffix)]))
if self.get_available_tables("nat"):
default_rules["nat"] = [ ]
self.our_chains["nat"] = set()
for chain in BUILT_IN_CHAINS["nat"]:
default_rules["nat"].append("-N %s_direct" % chain)
default_rules["nat"].append("-A %s -j %s_direct" % (chain, chain))
self.our_chains["nat"].add("%s_direct" % chain)
if chain in [ "PREROUTING", "POSTROUTING" ]:
for dispatch_suffix in ["ZONES_SOURCE", "ZONES"] if self._fw._allow_zone_drifting else ["ZONES"]:
default_rules["nat"].append("-N %s_%s" % (chain, dispatch_suffix))
default_rules["nat"].append("-A %s -j %s_%s" % (chain, chain, dispatch_suffix))
self.our_chains["nat"].update(set(["%s_%s" % (chain, dispatch_suffix)]))
default_rules["filter"] = []
self.our_chains["filter"] = set()
default_rules["filter"].append("-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED,DNAT -j ACCEPT")
default_rules["filter"].append("-A INPUT -i lo -j ACCEPT")
default_rules["filter"].append("-N INPUT_direct")
default_rules["filter"].append("-A INPUT -j INPUT_direct")
self.our_chains["filter"].update(set("INPUT_direct"))
for dispatch_suffix in ["ZONES_SOURCE", "ZONES"] if self._fw._allow_zone_drifting else ["ZONES"]:
default_rules["filter"].append("-N INPUT_%s" % (dispatch_suffix))
default_rules["filter"].append("-A INPUT -j INPUT_%s" % (dispatch_suffix))
self.our_chains["filter"].update(set("INPUT_%s" % (dispatch_suffix)))
if log_denied != "off":
default_rules["filter"].append("-A INPUT -m conntrack --ctstate INVALID %%LOGTYPE%% -j LOG --log-prefix 'STATE_INVALID_DROP: '")
default_rules["filter"].append("-A INPUT -m conntrack --ctstate INVALID -j DROP")
if log_denied != "off":
default_rules["filter"].append("-A INPUT %%LOGTYPE%% -j LOG --log-prefix 'FINAL_REJECT: '")
default_rules["filter"].append("-A INPUT -j %%REJECT%%")
default_rules["filter"].append("-A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED,DNAT -j ACCEPT")
default_rules["filter"].append("-A FORWARD -i lo -j ACCEPT")
default_rules["filter"].append("-N FORWARD_direct")
default_rules["filter"].append("-A FORWARD -j FORWARD_direct")
self.our_chains["filter"].update(set("FORWARD_direct"))
for direction in ["IN", "OUT"]:
for dispatch_suffix in ["ZONES_SOURCE", "ZONES"] if self._fw._allow_zone_drifting else ["ZONES"]:
default_rules["filter"].append("-N FORWARD_%s_%s" % (direction, dispatch_suffix))
default_rules["filter"].append("-A FORWARD -j FORWARD_%s_%s" % (direction, dispatch_suffix))
self.our_chains["filter"].update(set("FORWARD_%s_%s" % (direction, dispatch_suffix)))
if log_denied != "off":
default_rules["filter"].append("-A FORWARD -m conntrack --ctstate INVALID %%LOGTYPE%% -j LOG --log-prefix 'STATE_INVALID_DROP: '")
default_rules["filter"].append("-A FORWARD -m conntrack --ctstate INVALID -j DROP")
if log_denied != "off":
default_rules["filter"].append("-A FORWARD %%LOGTYPE%% -j LOG --log-prefix 'FINAL_REJECT: '")
default_rules["filter"].append("-A FORWARD -j %%REJECT%%")
default_rules["filter"] += [
"-N OUTPUT_direct",
"-A OUTPUT -o lo -j ACCEPT",
"-A OUTPUT -j OUTPUT_direct",
]
self.our_chains["filter"].update(set("OUTPUT_direct"))
final_default_rules = []
for table in default_rules:
if table not in self.get_available_tables():
continue
for rule in default_rules[table]:
final_default_rules.append(["-t", table] + splitArgs(rule))
return final_default_rules
def get_zone_table_chains(self, table):
if table == "filter":
return { "INPUT", "FORWARD_IN", "FORWARD_OUT" }
if table == "mangle":
if "mangle" in self.get_available_tables():
return { "PREROUTING" }
if table == "nat":
if "nat" in self.get_available_tables():
return { "PREROUTING", "POSTROUTING" }
if table == "raw":
if "raw" in self.get_available_tables():
return { "PREROUTING" }
return {}
def build_zone_source_interface_rules(self, enable, zone, interface,
table, chain, append=False):
# handle all zones in the same way here, now
# trust and block zone targets are handled now in __chain
opt = {
"PREROUTING": "-i",
"POSTROUTING": "-o",
"INPUT": "-i",
"FORWARD_IN": "-i",
"FORWARD_OUT": "-o",
"OUTPUT": "-o",
}[chain]
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS[chain], zone=zone)
action = "-g"
if enable and not append:
rule = [ "-I", "%s_ZONES" % chain, "%%ZONE_INTERFACE%%" ]
elif enable:
rule = [ "-A", "%s_ZONES" % chain ]
else:
rule = [ "-D", "%s_ZONES" % chain ]
if not append:
rule += ["%%ZONE_INTERFACE%%"]
rule += [ "-t", table, opt, interface, action, target ]
return [rule]
def build_zone_source_address_rules(self, enable, zone,
address, table, chain):
add_del = { True: "-I", False: "-D" }[enable]
opt = {
"PREROUTING": "-s",
"POSTROUTING": "-d",
"INPUT": "-s",
"FORWARD_IN": "-s",
"FORWARD_OUT": "-d",
"OUTPUT": "-d",
}[chain]
if self._fw._allow_zone_drifting:
zone_dispatch_chain = "%s_ZONES_SOURCE" % (chain)
else:
zone_dispatch_chain = "%s_ZONES" % (chain)
# iptables can not match destination MAC
if check_mac(address) and chain in ["POSTROUTING", "FORWARD_OUT", "OUTPUT"]:
return []
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS[chain], zone=zone)
action = "-g"
if address.startswith("ipset:"):
name = address[6:]
if opt == "-d":
opt = "dst"
else:
opt = "src"
flags = ",".join([opt] * self._fw.ipset.get_dimension(name))
rule = [ add_del, zone_dispatch_chain,
"%%ZONE_SOURCE%%", zone,
"-t", table,
"-m", "set", "--match-set", name,
flags, action, target ]
else:
if check_mac(address):
# outgoing can not be set
if opt == "-d":
return ""
rule = [ add_del, zone_dispatch_chain,
"%%ZONE_SOURCE%%", zone,
"-t", table,
"-m", "mac", "--mac-source", address.upper(),
action, target ]
else:
if check_single_address("ipv6", address):
address = normalizeIP6(address)
elif check_address("ipv6", address):
addr_split = address.split("/")
address = normalizeIP6(addr_split[0]) + "/" + addr_split[1]
rule = [ add_del, zone_dispatch_chain,
"%%ZONE_SOURCE%%", zone,
"-t", table,
opt, address, action, target ]
return [rule]
def build_zone_chain_rules(self, zone, table, chain):
_zone = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS[chain], zone=zone)
self.our_chains[table].update(set([_zone,
"%s_log" % _zone,
"%s_deny" % _zone,
"%s_pre" % _zone,
"%s_post" % _zone,
"%s_allow" % _zone]))
rules = []
rules.append([ "-N", _zone, "-t", table ])
rules.append([ "-N", "%s_pre" % _zone, "-t", table ])
rules.append([ "-N", "%s_log" % _zone, "-t", table ])
rules.append([ "-N", "%s_deny" % _zone, "-t", table ])
rules.append([ "-N", "%s_allow" % _zone, "-t", table ])
rules.append([ "-N", "%s_post" % _zone, "-t", table ])
rules.append([ "-A", _zone, "-t", table, "-j", "%s_pre" % _zone ])
rules.append([ "-A", _zone, "-t", table, "-j", "%s_log" % _zone ])
rules.append([ "-A", _zone, "-t", table, "-j", "%s_deny" % _zone ])
rules.append([ "-A", _zone, "-t", table, "-j", "%s_allow" % _zone ])
rules.append([ "-A", _zone, "-t", table, "-j", "%s_post" % _zone ])
target = self._fw.zone._zones[zone].target
if self._fw.get_log_denied() != "off":
if table == "filter" and \
chain in [ "INPUT", "FORWARD_IN", "FORWARD_OUT", "OUTPUT" ]:
if target in [ "REJECT", "%%REJECT%%" ]:
rules.append([ "-A", _zone, "-t", table, "%%LOGTYPE%%",
"-j", "LOG", "--log-prefix",
"\"%s_REJECT: \"" % _zone ])
if target == "DROP":
rules.append([ "-A", _zone, "-t", table, "%%LOGTYPE%%",
"-j", "LOG", "--log-prefix",
"\"%s_DROP: \"" % _zone ])
# Handle trust, block and drop zones:
# Add an additional rule with the zone target (accept, reject
# or drop) to the base zone only in the filter table.
# Otherwise it is not be possible to have a zone with drop
# target, that is allowing traffic that is locally initiated
# or that adds additional rules. (RHBZ#1055190)
if table == "filter" and \
target in [ "ACCEPT", "REJECT", "%%REJECT%%", "DROP" ] and \
chain in [ "INPUT", "FORWARD_IN", "FORWARD_OUT", "OUTPUT" ]:
rules.append([ "-A", _zone, "-t", table, "-j", target ])
return rules
def _rule_limit(self, limit):
if limit:
return [ "-m", "limit", "--limit", limit.value ]
return []
def _rich_rule_chain_suffix(self, rich_rule):
if type(rich_rule.element) in [Rich_Masquerade, Rich_ForwardPort, Rich_IcmpBlock]:
# These are special and don't have an explicit action
pass
elif rich_rule.action:
if type(rich_rule.action) not in [Rich_Accept, Rich_Reject, Rich_Drop, Rich_Mark]:
raise FirewallError(INVALID_RULE, "Unknown action %s" % type(rich_rule.action))
else:
raise FirewallError(INVALID_RULE, "No rule action specified.")
if rich_rule.priority == 0:
if type(rich_rule.element) in [Rich_Masquerade, Rich_ForwardPort] or \
type(rich_rule.action) in [Rich_Accept, Rich_Mark]:
return "allow"
elif type(rich_rule.element) in [Rich_IcmpBlock] or \
type(rich_rule.action) in [Rich_Reject, Rich_Drop]:
return "deny"
elif rich_rule.priority < 0:
return "pre"
else:
return "post"
def _rich_rule_chain_suffix_from_log(self, rich_rule):
if not rich_rule.log and not rich_rule.audit:
raise FirewallError(INVALID_RULE, "Not log or audit")
if rich_rule.priority == 0:
return "log"
elif rich_rule.priority < 0:
return "pre"
else:
return "post"
def _rich_rule_priority_fragment(self, rich_rule):
if rich_rule.priority == 0:
return []
return ["%%RICH_RULE_PRIORITY%%", rich_rule.priority]
def _rich_rule_log(self, rich_rule, enable, table, target, rule_fragment):
if not rich_rule.log:
return []
add_del = { True: "-A", False: "-D" }[enable]
chain_suffix = self._rich_rule_chain_suffix_from_log(rich_rule)
rule = ["-t", table, add_del, "%s_%s" % (target, chain_suffix)]
rule += self._rich_rule_priority_fragment(rich_rule)
rule += rule_fragment + [ "-j", "LOG" ]
if rich_rule.log.prefix:
rule += [ "--log-prefix", "'%s'" % rich_rule.log.prefix ]
if rich_rule.log.level:
rule += [ "--log-level", "%s" % rich_rule.log.level ]
rule += self._rule_limit(rich_rule.log.limit)
return rule
def _rich_rule_audit(self, rich_rule, enable, table, target, rule_fragment):
if not rich_rule.audit:
return []
add_del = { True: "-A", False: "-D" }[enable]
chain_suffix = self._rich_rule_chain_suffix_from_log(rich_rule)
rule = ["-t", table, add_del, "%s_%s" % (target, chain_suffix)]
rule += self._rich_rule_priority_fragment(rich_rule)
rule += rule_fragment
if type(rich_rule.action) == Rich_Accept:
_type = "accept"
elif type(rich_rule.action) == Rich_Reject:
_type = "reject"
elif type(rich_rule.action) == Rich_Drop:
_type = "drop"
else:
_type = "unknown"
rule += [ "-j", "AUDIT", "--type", _type ]
rule += self._rule_limit(rich_rule.audit.limit)
return rule
def _rich_rule_action(self, zone, rich_rule, enable, table, target, rule_fragment):
if not rich_rule.action:
return []
add_del = { True: "-A", False: "-D" }[enable]
chain_suffix = self._rich_rule_chain_suffix(rich_rule)
chain = "%s_%s" % (target, chain_suffix)
if type(rich_rule.action) == Rich_Accept:
rule_action = [ "-j", "ACCEPT" ]
elif type(rich_rule.action) == Rich_Reject:
rule_action = [ "-j", "REJECT" ]
if rich_rule.action.type:
rule_action += [ "--reject-with", rich_rule.action.type ]
elif type(rich_rule.action) == Rich_Drop:
rule_action = [ "-j", "DROP" ]
elif type(rich_rule.action) == Rich_Mark:
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS["PREROUTING"],
zone=zone)
table = "mangle"
chain = "%s_%s" % (target, chain_suffix)
rule_action = [ "-j", "MARK", "--set-xmark", rich_rule.action.set ]
else:
raise FirewallError(INVALID_RULE,
"Unknown action %s" % type(rich_rule.action))
rule = ["-t", table, add_del, chain]
rule += self._rich_rule_priority_fragment(rich_rule)
rule += rule_fragment + rule_action
rule += self._rule_limit(rich_rule.action.limit)
return rule
def _rich_rule_destination_fragment(self, rich_dest):
if not rich_dest:
return []
rule_fragment = []
if rich_dest.invert:
rule_fragment.append("!")
if check_single_address("ipv6", rich_dest.addr):
rule_fragment += [ "-d", normalizeIP6(rich_dest.addr) ]
elif check_address("ipv6", rich_dest.addr):
addr_split = rich_dest.addr.split("/")
rule_fragment += [ "-d", normalizeIP6(addr_split[0]) + "/" + addr_split[1] ]
else:
rule_fragment += [ "-d", rich_dest.addr ]
return rule_fragment
def _rich_rule_source_fragment(self, rich_source):
if not rich_source:
return []
rule_fragment = []
if rich_source.addr:
if rich_source.invert:
rule_fragment.append("!")
if check_single_address("ipv6", rich_source.addr):
rule_fragment += [ "-s", normalizeIP6(rich_source.addr) ]
elif check_address("ipv6", rich_source.addr):
addr_split = rich_source.addr.split("/")
rule_fragment += [ "-s", normalizeIP6(addr_split[0]) + "/" + addr_split[1] ]
else:
rule_fragment += [ "-s", rich_source.addr ]
elif hasattr(rich_source, "mac") and rich_source.mac:
rule_fragment += [ "-m", "mac" ]
if rich_source.invert:
rule_fragment.append("!")
rule_fragment += [ "--mac-source", rich_source.mac ]
elif hasattr(rich_source, "ipset") and rich_source.ipset:
rule_fragment += [ "-m", "set" ]
if rich_source.invert:
rule_fragment.append("!")
flags = self._fw.zone._ipset_match_flags(rich_source.ipset, "src")
rule_fragment += [ "--match-set", rich_source.ipset, flags ]
return rule_fragment
def build_zone_ports_rules(self, enable, zone, proto, port, destination=None, rich_rule=None):
add_del = { True: "-A", False: "-D" }[enable]
table = "filter"
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS["INPUT"],
zone=zone)
rule_fragment = [ "-p", proto ]
if port:
rule_fragment += [ "--dport", "%s" % portStr(port) ]
if destination:
rule_fragment += [ "-d", destination ]
if rich_rule:
rule_fragment += self._rich_rule_destination_fragment(rich_rule.destination)
rule_fragment += self._rich_rule_source_fragment(rich_rule.source)
if not rich_rule or type(rich_rule.action) != Rich_Mark:
rule_fragment += [ "-m", "conntrack", "--ctstate", "NEW,UNTRACKED" ]
rules = []
if rich_rule:
rules.append(self._rich_rule_log(rich_rule, enable, table, target, rule_fragment))
rules.append(self._rich_rule_audit(rich_rule, enable, table, target, rule_fragment))
rules.append(self._rich_rule_action(zone, rich_rule, enable, table, target, rule_fragment))
else:
rules.append([add_del, "%s_allow" % (target), "-t", table] +
rule_fragment + [ "-j", "ACCEPT" ])
return rules
def build_zone_protocol_rules(self, enable, zone, protocol, destination=None, rich_rule=None):
add_del = { True: "-A", False: "-D" }[enable]
table = "filter"
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS["INPUT"], zone=zone)
rule_fragment = [ "-p", protocol ]
if destination:
rule_fragment += [ "-d", destination ]
if rich_rule:
rule_fragment += self._rich_rule_destination_fragment(rich_rule.destination)
rule_fragment += self._rich_rule_source_fragment(rich_rule.source)
if not rich_rule or type(rich_rule.action) != Rich_Mark:
rule_fragment += [ "-m", "conntrack", "--ctstate", "NEW,UNTRACKED" ]
rules = []
if rich_rule:
rules.append(self._rich_rule_log(rich_rule, enable, table, target, rule_fragment))
rules.append(self._rich_rule_audit(rich_rule, enable, table, target, rule_fragment))
rules.append(self._rich_rule_action(zone, rich_rule, enable, table, target, rule_fragment))
else:
rules.append([add_del, "%s_allow" % (target), "-t", table] +
rule_fragment + [ "-j", "ACCEPT" ])
return rules
def build_zone_source_ports_rules(self, enable, zone, proto, port,
destination=None, rich_rule=None):
add_del = { True: "-A", False: "-D" }[enable]
table = "filter"
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS["INPUT"], zone=zone)
rule_fragment = [ "-p", proto ]
if port:
rule_fragment += [ "--sport", "%s" % portStr(port) ]
if destination:
rule_fragment += [ "-d", destination ]
if rich_rule:
rule_fragment += self._rich_rule_destination_fragment(rich_rule.destination)
rule_fragment += self._rich_rule_source_fragment(rich_rule.source)
if not rich_rule or type(rich_rule.action) != Rich_Mark:
rule_fragment += [ "-m", "conntrack", "--ctstate", "NEW,UNTRACKED" ]
rules = []
if rich_rule:
rules.append(self._rich_rule_log(rich_rule, enable, table, target, rule_fragment))
rules.append(self._rich_rule_audit(rich_rule, enable, table, target, rule_fragment))
rules.append(self._rich_rule_action(zone, rich_rule, enable, table, target, rule_fragment))
else:
rules.append([add_del, "%s_allow" % (target), "-t", table] +
rule_fragment + [ "-j", "ACCEPT" ])
return rules
def build_zone_helper_ports_rules(self, enable, zone, proto, port,
destination, helper_name, module_short_name):
add_del = { True: "-A", False: "-D" }[enable]
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS["PREROUTING"],
zone=zone)
rule = [ add_del, "%s_allow" % (target), "-t", "raw", "-p", proto ]
if port:
rule += [ "--dport", "%s" % portStr(port) ]
if destination:
rule += [ "-d", destination ]
rule += [ "-j", "CT", "--helper", module_short_name ]
return [rule]
def build_zone_masquerade_rules(self, enable, zone, rich_rule=None):
add_del = { True: "-A", False: "-D" }[enable]
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS["POSTROUTING"],
zone=zone)
rule_fragment = []
if rich_rule:
chain_suffix = self._rich_rule_chain_suffix(rich_rule)
rule_fragment += self._rich_rule_priority_fragment(rich_rule)
rule_fragment += self._rich_rule_destination_fragment(rich_rule.destination)
rule_fragment += self._rich_rule_source_fragment(rich_rule.source)
else:
chain_suffix = "allow"
rules = []
rules.append(["-t", "nat", add_del, "%s_%s" % (target, chain_suffix)]
+ rule_fragment +
[ "!", "-o", "lo", "-j", "MASQUERADE" ])
# FORWARD_OUT
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS["FORWARD_OUT"],
zone=zone)
rule_fragment = []
if rich_rule:
chain_suffix = self._rich_rule_chain_suffix(rich_rule)
rule_fragment += self._rich_rule_priority_fragment(rich_rule)
rule_fragment += self._rich_rule_destination_fragment(rich_rule.destination)
rule_fragment += self._rich_rule_source_fragment(rich_rule.source)
else:
chain_suffix = "allow"
rules.append(["-t", "filter", add_del, "%s_%s" % (target, chain_suffix)]
+ rule_fragment +
["-m", "conntrack", "--ctstate", "NEW,UNTRACKED", "-j", "ACCEPT" ])
return rules
def build_zone_forward_port_rules(self, enable, zone, port,
protocol, toport, toaddr, rich_rule=None):
add_del = { True: "-A", False: "-D" }[enable]
to = ""
if toaddr:
if check_single_address("ipv6", toaddr):
to += "[%s]" % normalizeIP6(toaddr)
else:
to += toaddr
if toport and toport != "":
to += ":%s" % portStr(toport, "-")
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS["PREROUTING"],
zone=zone)
rule_fragment = []
if rich_rule:
chain_suffix = self._rich_rule_chain_suffix(rich_rule)
rule_fragment = self._rich_rule_priority_fragment(rich_rule)
rule_fragment += self._rich_rule_destination_fragment(rich_rule.destination)
rule_fragment += self._rich_rule_source_fragment(rich_rule.source)
else:
chain_suffix = "allow"
rules = []
if rich_rule:
rules.append(self._rich_rule_log(rich_rule, enable, "nat", target, rule_fragment))
rules.append(["-t", "nat", add_del, "%s_%s" % (target, chain_suffix)]
+ rule_fragment +
["-p", protocol, "--dport", portStr(port),
"-j", "DNAT", "--to-destination", to])
return rules
def build_zone_icmp_block_rules(self, enable, zone, ict, rich_rule=None):
table = "filter"
add_del = { True: "-A", False: "-D" }[enable]
if self.ipv == "ipv4":
proto = [ "-p", "icmp" ]
match = [ "-m", "icmp", "--icmp-type", ict.name ]
else:
proto = [ "-p", "ipv6-icmp" ]
match = [ "-m", "icmp6", "--icmpv6-type", ict.name ]
if rich_rule and rich_rule.action and isinstance(rich_rule.action, Rich_Mark):
chains = ["PREROUTING"]
else:
chains = ["INPUT", "FORWARD_IN"]
rules = []
for chain in chains:
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS[chain],
zone=zone)
if self._fw.zone.query_icmp_block_inversion(zone):
final_chain = "%s_allow" % target
final_target = "ACCEPT"
else:
final_chain = "%s_deny" % target
final_target = "%%REJECT%%"
rule_fragment = []
if rich_rule:
rule_fragment += self._rich_rule_destination_fragment(rich_rule.destination)
rule_fragment += self._rich_rule_source_fragment(rich_rule.source)
rule_fragment += proto + match
if rich_rule:
rules.append(self._rich_rule_log(rich_rule, enable, table, target, rule_fragment))
rules.append(self._rich_rule_audit(rich_rule, enable, table, target, rule_fragment))
if rich_rule.action:
rules.append(self._rich_rule_action(zone, rich_rule, enable, table, target, rule_fragment))
else:
chain_suffix = self._rich_rule_chain_suffix(rich_rule)
rules.append(["-t", table, add_del, "%s_%s" % (target, chain_suffix)]
+ self._rich_rule_priority_fragment(rich_rule)
+ rule_fragment +
[ "-j", "%%REJECT%%" ])
else:
if self._fw.get_log_denied() != "off" and final_target != "ACCEPT":
rules.append([ add_del, final_chain, "-t", table ]
+ rule_fragment +
[ "%%LOGTYPE%%", "-j", "LOG",
"--log-prefix", "\"%s_ICMP_BLOCK: \"" % zone ])
rules.append([ add_del, final_chain, "-t", table ]
+ rule_fragment +
[ "-j", final_target ])
return rules
def build_zone_icmp_block_inversion_rules(self, enable, zone):
table = "filter"
rules = []
for chain in [ "INPUT", "FORWARD_IN" ]:
rule_idx = 6
_zone = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS[chain],
zone=zone)
if self._fw.zone.query_icmp_block_inversion(zone):
ibi_target = "%%REJECT%%"
if self._fw.get_log_denied() != "off":
if enable:
rule = [ "-I", _zone, str(rule_idx) ]
else:
rule = [ "-D", _zone ]
rule = rule + [ "-t", table, "-p", "%%ICMP%%",
"%%LOGTYPE%%",
"-j", "LOG", "--log-prefix",
"\"%s_ICMP_BLOCK: \"" % _zone ]
rules.append(rule)
rule_idx += 1
else:
ibi_target = "ACCEPT"
if enable:
rule = [ "-I", _zone, str(rule_idx) ]
else:
rule = [ "-D", _zone ]
rule = rule + [ "-t", table, "-p", "%%ICMP%%", "-j", ibi_target ]
rules.append(rule)
return rules
def build_zone_rich_source_destination_rules(self, enable, zone, rich_rule):
table = "filter"
target = DEFAULT_ZONE_TARGET.format(chain=SHORTCUTS["INPUT"],
zone=zone)
rule_fragment = []
rule_fragment += self._rich_rule_destination_fragment(rich_rule.destination)
rule_fragment += self._rich_rule_source_fragment(rich_rule.source)
rules = []
rules.append(self._rich_rule_log(rich_rule, enable, table, target, rule_fragment))
rules.append(self._rich_rule_audit(rich_rule, enable, table, target, rule_fragment))
rules.append(self._rich_rule_action(zone, rich_rule, enable, table, target, rule_fragment))
return rules
def is_ipv_supported(self, ipv):
return ipv == self.ipv
class ip6tables(ip4tables):
ipv = "ipv6"
name = "ip6tables"
def build_rpfilter_rules(self, log_denied=False):
rules = []
rules.append([ "-I", "PREROUTING", "-t", "raw",
"-m", "rpfilter", "--invert", "-j", "DROP" ])
if log_denied != "off":
rules.append([ "-I", "PREROUTING", "-t", "raw",
"-m", "rpfilter", "--invert",
"-j", "LOG",
"--log-prefix", "rpfilter_DROP: " ])
rules.append([ "-I", "PREROUTING", "-t", "raw",
"-p", "ipv6-icmp",
"--icmpv6-type=neighbour-solicitation",
"-j", "ACCEPT" ]) # RHBZ#1575431, kernel bug in 4.16-4.17
rules.append([ "-I", "PREROUTING", "-t", "raw",
"-p", "ipv6-icmp",
"--icmpv6-type=router-advertisement",
"-j", "ACCEPT" ]) # RHBZ#1058505
return rules
def build_rfc3964_ipv4_rules(self):
daddr_list = [
"::0.0.0.0/96", # IPv4 compatible
"::ffff:0.0.0.0/96", # IPv4 mapped
"2002:0000::/24", # 0.0.0.0/8 (the system has no address assigned yet)
"2002:0a00::/24", # 10.0.0.0/8 (private)
"2002:7f00::/24", # 127.0.0.0/8 (loopback)
"2002:ac10::/28", # 172.16.0.0/12 (private)
"2002:c0a8::/32", # 192.168.0.0/16 (private)
"2002:a9fe::/32", # 169.254.0.0/16 (IANA Assigned DHCP link-local)
"2002:e000::/19", # 224.0.0.0/4 (multicast), 240.0.0.0/4 (reserved and broadcast)
]
chain_name = "RFC3964_IPv4"
self.our_chains["filter"].add(chain_name)
rules = []
rules.append(["-t", "filter", "-N", chain_name])
for daddr in daddr_list:
rules.append(["-t", "filter", "-I", chain_name,
"-d", daddr, "-j", "REJECT", "--reject-with",
"addr-unreach"])
if self._fw._log_denied in ["unicast", "all"]:
rules.append(["-t", "filter", "-I", chain_name,
"-d", daddr, "-j", "LOG",
"--log-prefix", "\"RFC3964_IPv4_REJECT: \""])
# Inject into FORWARD and OUTPUT chains
rules.append(["-t", "filter", "-I", "OUTPUT", "3",
"-j", chain_name])
rules.append(["-t", "filter", "-I", "FORWARD", "4",
"-j", chain_name])
return rules