added nftables support to server.py

data/Dockerfiles/netfilter/server.py

@@ -7,6 +7,7 @@ import time
 import atexit
 import signal
 import ipaddress
+import nftables
 from collections import Counter
 from random import randint
 from threading import Thread
@@ -43,6 +44,10 @@ quit_now = False
 exit_code = 0
 lock = Lock()
 
+backend = sys.argv[1]
+nft = None
+nft_chain_names = {}
+
 def log(priority, message):
   tolog = {}
   tolog['time'] = int(round(time.time()))
@@ -60,6 +65,17 @@ def logCrit(message):
 def logInfo(message):
   log('info', message)
 
+#nftables
+if backend == 'nftables':
+  logInfo('Using Nftables backend')
+  nft = nftables.Nftables()
+  nft.set_json_output(True)
+  nft.set_handle_output(True)
+  nft_chain_names = {'ip': {'filter': {'input': '', 'forward': ''}, 'nat': {'postrouting': ''} },
+                    'ip6': {'filter': {'input': '', 'forward': ''}, 'nat': {'postrouting': ''} } }
+else:
+  logInfo('Using Iptables backend')
+
 def refreshF2boptions():
   global f2boptions
   global quit_now
@@ -115,13 +131,437 @@ def refreshF2bregex():
 if r.exists('F2B_LOG'):
   r.rename('F2B_LOG', 'NETFILTER_LOG')
 
+# Nftables functions
+def nft_exec_dict(query: dict):
+  global nft
+
+  if not query: return False
+
+  rc, output, error = nft.json_cmd(query)
+  if rc != 0:
+    #logCrit(f"Nftables Error: {error}")
+    return False
+
+  # Prevent returning False or empty string on commands that do not produce output
+  if rc == 0 and len(output) == 0:
+    return True
+  
+  return output
+
+def get_base_dict():
+  return {'nftables': [{ 'metainfo': { 'json_schema_version': 1} } ] }
+
+def search_current_chains():
+  global nft_chain_names
+  nft_chain_priority = {'ip': {'filter': {'input': 1, 'forward': 1}, 'nat': {'postrouting': 111} },
+                    'ip6': {'filter': {'input': 1, 'forward': 1}, 'nat': {'postrouting': 111} } }
+
+  # Command: 'nft list chains'
+  _list_opts = dict(chains='null')
+  _list = dict(list=_list_opts)
+  command = get_base_dict()
+  command['nftables'].append(_list)
+  kernel_ruleset = nft_exec_dict(command)
+  if kernel_ruleset:
+    for object in kernel_ruleset['nftables']:
+      chain = object.get("chain")
+      if not chain:
+        continue
+
+      _family = chain['family']
+      _table = chain['table']
+
+      hook = chain.get("hook")
+      if not hook or hook not in nft_chain_names[_family][_table]:
+        continue
+
+      _hook = chain['hook']
+
+      priority = chain.get("prio")
+      if priority is None:
+        continue
+
+      if priority < nft_chain_priority[_family][_table][_hook]:
+          # at this point, we know the chain has:
+          # hook and priority set
+          # and it has the lowest priority
+          nft_chain_priority[_family][_table][_hook] = priority
+          nft_chain_names[_family][_table][_hook] = chain['name']
+
+def search_for_chain(kernel_ruleset: dict, chain_name: str):
+  found = False
+  for object in kernel_ruleset["nftables"]:
+      chain = object.get("chain")
+      if not chain:
+          continue
+      ch_name = chain.get("name")
+      if ch_name == chain_name:
+          found = True
+          break
+  return found
+
+def get_chain_dict(_family: str, _name: str):
+  # nft (add | create) chain [<family>] <table> <name> 
+  _chain_opts = dict(family = _family,
+                        table = 'filter',
+                        name = _name  )
+
+  _chain = dict(chain = _chain_opts)
+  _add = dict(add = _chain)
+  final_chain = get_base_dict()
+  final_chain["nftables"].append(_add)
+  return final_chain
+
+def get_mailcow_jump_rule_dict(_family: str, _chain: str):
+  _jump_rule = get_base_dict()
+  _expr_opt=[]
+  _expr_counter = dict(family = _family, table = 'filter', packets = 0, bytes = 0)
+  _counter_dict = dict(counter = _expr_counter)
+  _expr_opt.append(_counter_dict)
+
+  _expr_jump = dict(target = 'MAILCOW')
+  _jump_opts = dict(jump = _expr_jump)
+
+  _expr_opt.append(_jump_opts)
+
+  _rule_params = dict(family = _family,
+                      table = 'filter',
+                      chain = _chain,
+                      expr = _expr_opt,
+                      comment = "mailcow"
+  )
+  _opts_rule = dict(rule = _rule_params)
+  _add_rule = dict(insert = _opts_rule)
+
+  _jump_rule["nftables"].append(_add_rule)
+
+  return _jump_rule
+
+def insert_mailcow_chains(_family: str):
+  nft_input_chain = nft_chain_names[_family]['filter']['input']
+  nft_forward_chain = nft_chain_names[_family]['filter']['forward']
+  # Command: 'nft list table <family> filter'
+  _table_opts = dict(family=_family, name='filter')
+  _table = dict(table=_table_opts)
+  _list = dict(list=_table)
+  command = get_base_dict()
+  command['nftables'].append(_list)
+  kernel_ruleset = nft_exec_dict(command)
+  if kernel_ruleset:
+    # MAILCOW chain
+    if not search_for_chain(kernel_ruleset, "MAILCOW"):
+      cadena = get_chain_dict(_family, "MAILCOW")
+      if(nft_exec_dict(cadena)):
+        logInfo(f"MAILCOW {_family} chain created successfully.")
+
+    input_jump_found, forward_jump_found = False, False
+
+    for object in kernel_ruleset["nftables"]:
+      if not object.get("rule"):
+        continue
+
+      rule = object["rule"]
+      if rule["chain"] == nft_input_chain:
+        if rule.get("comment") and rule["comment"] == "mailcow":
+          input_jump_found = True
+      if rule["chain"] == nft_forward_chain:
+        if rule.get("comment") and rule["comment"] == "mailcow":
+          forward_jump_found = True
+
+    if not input_jump_found and nft_input_chain:
+      command = get_mailcow_jump_rule_dict(_family, nft_input_chain)
+      nft_exec_dict(command)
+
+    if not forward_jump_found and nft_forward_chain:
+      command = get_mailcow_jump_rule_dict(_family, nft_forward_chain)
+      nft_exec_dict(command)
+
+def delete_nat_rule(_family:str, _chain: str, _handle:str):
+  delete_command = get_base_dict()
+  _rule_opts = dict(family = _family,
+                      table = 'nat',
+                      chain = _chain,
+                      handle = _handle
+                    )
+  _rule = dict(rule = _rule_opts)
+  _delete = dict(delete = _rule)
+  delete_command["nftables"].append(_delete)
+
+  return nft_exec_dict(delete_command)
+
+def snat_rule(_family: str, snat_target: str):
+  chain_name = nft_chain_names[_family]['nat']['postrouting']
+
+  # no postrouting chain, may occur if docker has ipv6 disabled.
+  if not chain_name: return
+
+  # Command: nft list chain <family> nat <chain_name>
+  _chain_opts = dict(family=_family, table='nat', name=chain_name)
+  _chain = dict(chain=_chain_opts)
+  _list = dict(list=_chain)
+  command = get_base_dict()
+  command['nftables'].append(_list)
+  kernel_ruleset = nft_exec_dict(command)
+  if not kernel_ruleset:
+    return
+
+  rule_position = 0
+  rule_handle = None
+  rule_found = False
+  for object in kernel_ruleset["nftables"]:
+    if not object.get("rule"):
+      continue
+
+    rule = object["rule"]
+    if not rule.get("comment") or not rule["comment"] == "mailcow":
+      rule_position +=1
+      continue
+    else:
+      rule_found = True
+      rule_handle = rule["handle"]
+      break
+
+  if _family == "ip":
+    source_address = os.getenv('IPV4_NETWORK', '172.22.1') + '.0/24'
+  else:
+    source_address = os.getenv('IPV6_NETWORK', 'fd4d:6169:6c63:6f77::/64')
+
+  tmp_addr = re.split(r'/', source_address)
+  dest_ip = tmp_addr[0]
+  dest_len = int(tmp_addr[1])
+
+  if rule_found:
+    saddr_ip = rule["expr"][0]["match"]["right"]["prefix"]["addr"]
+    saddr_len = int(rule["expr"][0]["match"]["right"]["prefix"]["len"])
+
+    daddr_ip = rule["expr"][1]["match"]["right"]["prefix"]["addr"]
+    daddr_len = int(rule["expr"][1]["match"]["right"]["prefix"]["len"])
+    match = all((
+              saddr_ip == dest_ip,
+              saddr_len == dest_len,
+              daddr_ip == dest_ip,
+              daddr_len == dest_len
+            ))
+    try:
+      if rule_position == 0:
+        if not match:
+          # Position 0 , it is a mailcow rule , but it does not have the same parameters
+          if delete_nat_rule(_family, chain_name, rule_handle):
+            logInfo(f'Remove rule for source network {saddr_ip}/{saddr_len} to SNAT target {snat_target} from POSTROUTING chain with handle {rule_handle}')
+
+      else:
+        # Position > 0 and is mailcow rule
+        if delete_nat_rule(_family, chain_name, rule_handle):
+          logInfo(f'Remove rule for source network {saddr_ip}/{saddr_len} to SNAT target {snat_target} from POSTROUTING chain with handle {rule_handle}')
+    except:
+        logCrit(f"Error running SNAT on {_family}, retrying..." )
+  else:
+    # rule not found
+    json_command = get_base_dict()
+    try:
+      payload_fields = dict(protocol = _family, field = "saddr")
+      payload_dict = dict(payload = payload_fields)
+      payload_fields2 = dict(protocol = _family, field = "daddr")
+      payload_dict2 = dict(payload = payload_fields2)
+      prefix_fields=dict(addr = dest_ip, len = int(dest_len))
+      prefix_dict=dict(prefix = prefix_fields)
+
+      snat_addr = dict(addr = snat_target)
+      snat_dict = dict(snat = snat_addr)
+
+      expr_counter = dict(family = _family, table = "nat", packets = 0, bytes = 0)
+      counter_dict = dict(counter = expr_counter)
+
+      match_fields1 = dict(op = "==", left = payload_dict, right = prefix_dict)
+      match_dict1 = dict(match = match_fields1)
+
+      match_fields2 = dict(op = "!=", left = payload_dict2, right = prefix_dict )
+      match_dict2 = dict(match = match_fields2)
+      expr_list = [
+                  match_dict1,
+                  match_dict2,
+                  counter_dict,
+                  snat_dict
+                  ]
+      rule_fields = dict(family = _family,
+                        table = "nat",
+                        chain = chain_name,
+                        comment = "mailcow",
+                        expr = expr_list
+                        )
+      rule_dict = dict(rule = rule_fields)
+      insert_dict = dict(insert = rule_dict)
+      json_command["nftables"].append(insert_dict)
+      if(nft_exec_dict(json_command)):
+        logInfo(f"Added {_family} POSTROUTING rule for source network {dest_ip} to {snat_target}")
+    except:
+      logCrit(f"Error running SNAT on {_family}, retrying...")
+
+def get_chain_handle(_family: str, _table: str, chain_name: str):
+  chain_handle = None
+  # Command: 'nft list chains {family}'
+  _chain_opts = dict(family=_family)
+  _chain = dict(chains=_chain_opts)
+  _list = dict(list=_chain)
+  command = get_base_dict()
+  command['nftables'].append(_list)
+  kernel_ruleset = nft_exec_dict(command)
+  if kernel_ruleset:
+    for object in kernel_ruleset["nftables"]:
+      if not object.get("chain"):
+        continue
+      chain = object["chain"]
+      if chain["family"] == _family and chain["table"] == _table and chain["name"] == chain_name:
+        chain_handle = chain["handle"]
+        break
+  return chain_handle
+
+def get_rules_handle(_family: str, _table: str, chain_name: str):
+  rule_handle = []
+  # Command: 'nft list chain {family} {table} {chain_name}'
+  _chain_opts = dict(family=_family, table=_table, name=chain_name)
+  _chain = dict(chain=_chain_opts)
+  _list = dict(list=_chain)
+  command = get_base_dict()
+  command['nftables'].append(_list)
+
+  kernel_ruleset = nft_exec_dict(command)
+  if kernel_ruleset:
+    for object in kernel_ruleset["nftables"]:
+      if not object.get("rule"):
+        continue
+
+      rule = object["rule"]
+      if rule["family"] == _family and rule["table"] == _table and rule["chain"] == chain_name:
+        if rule.get("comment") and rule["comment"] == "mailcow":
+          rule_handle.append(rule["handle"])
+  return rule_handle
+
+def get_ban_ip_dict(ipaddr: str, _family: str):
+  json_command = get_base_dict()
+
+  expr_opt = []
+  if re.search(r'/', ipaddr):
+    divided = re.split(r'/', ipaddr)
+    prefix_dict=dict(addr = divided[0],
+                    len = int(divided[1]) )
+    right_dict = dict(prefix = prefix_dict)
+  else:
+    right_dict = ipaddr
+
+  payload_dict = dict(protocol = _family, field="saddr" )
+  left_dict = dict(payload = payload_dict)
+  match_dict = dict(op = "==", left = left_dict, right = right_dict )
+  match_base = dict(match = match_dict)
+  expr_opt.append(match_base)
+
+  expr_counter = dict(family = _family, table = "filter", packets = 0, bytes = 0)
+  counter_dict = dict(counter = expr_counter)
+  expr_opt.append(counter_dict)
+
+  drop_dict = dict(drop = "null")
+  expr_opt.append(drop_dict)
+
+  rule_dict = dict(family = _family, table = "filter", chain = "MAILCOW", expr = expr_opt)
+
+  base_rule = dict(rule = rule_dict)
+  base_dict = dict(insert = base_rule)
+  json_command["nftables"].append(base_dict)
+
+  return json_command
+
+def get_unban_ip_dict(ipaddr:str, _family: str):
+  json_command = get_base_dict()
+  # Command: 'nft list chain {s_family} filter  MAILCOW'
+  _chain_opts = dict(family=_family, table='filter', name='MAILCOW')
+  _chain = dict(chain=_chain_opts)
+  _list = dict(list=_chain)
+  command = get_base_dict()
+  command['nftables'].append(_list)
+  kernel_ruleset = nft_exec_dict(command)
+  rule_handle = None
+  if kernel_ruleset:
+    for object in kernel_ruleset["nftables"]:
+      if not object.get("rule"):
+        continue
+
+      rule = object["rule"]["expr"][0]["match"]
+      left_opt = rule["left"]["payload"]
+      if not left_opt["protocol"] == _family:
+        continue
+      if not left_opt["field"] =="saddr":
+        continue
+
+      # ip currently banned
+      rule_right = rule["right"]
+      if isinstance(rule_right, dict):
+        current_rule_ip = rule_right["prefix"]["addr"]
+        current_rule_len = int(rule_right["prefix"]["len"])
+      else:
+        current_rule_ip = rule_right
+        current_rule_len = 32 if _family == 'ip' else 128
+
+      # ip to ban
+      if re.search(r'/', ipaddr):
+        divided = re.split(r'/', ipaddr)
+        candidate_ip = divided[0]
+        candidate_len = int(divided[1])
+      else:
+        candidate_ip = ipaddr
+        candidate_len = 32 if _family == 'ip' else 128
+
+      if all((current_rule_ip == candidate_ip,
+              current_rule_len and candidate_len,
+              current_rule_len == candidate_len )):
+        rule_handle = object["rule"]["handle"]
+        break
+
+    if rule_handle is not None:
+      mailcow_rule = dict(family = _family, table = "filter", chain = "MAILCOW", handle = rule_handle)
+      del_rule = dict(rule = mailcow_rule)
+      delete_rule=dict(delete = del_rule)
+      json_command["nftables"].append(delete_rule)
+    else:
+        return False
+
+  return json_command
+
+def check_mailcow_chains(family: str, chain: str):
+  position = 0
+  rule_found = False
+  chain_name = nft_chain_names[family]['filter'][chain]
+
+  if not chain_name: return None
+
+  _chain_opts = dict(family=family, table='filter', name=chain_name)
+  _chain = dict(chain=_chain_opts)
+  _list = dict(list=_chain)
+  command = get_base_dict()
+  command['nftables'].append(_list)
+  kernel_ruleset = nft_exec_dict(command)
+  if kernel_ruleset:
+    for object in kernel_ruleset["nftables"]:
+      if not object.get("rule"):
+        continue
+      rule = object["rule"]
+      if rule.get("comment") and rule["comment"] == "mailcow":
+        rule_found = True
+        break
+
+      position+=1
+
+  return position if rule_found else False
+
+# Mailcow
 def mailcowChainOrder():
   global lock
   global quit_now
   global exit_code
+
   while not quit_now:
     time.sleep(10)
     with lock:
+      if backend == 'iptables':
         filter4_table = iptc.Table(iptc.Table.FILTER)
         filter6_table = iptc.Table6(iptc.Table6.FILTER)
         filter4_table.refresh()
@@ -142,6 +582,21 @@ def mailcowChainOrder():
               logCrit('Error in %s chain: MAILCOW target not found, restarting container' % (chain.name))
               quit_now = True
               exit_code = 2
+      else:
+        for family in ["ip", "ip6"]:
+          for chain in ['input', 'forward']:
+            chain_position = check_mailcow_chains(family, chain)
+            if chain_position is None: continue
+
+            if chain_position is False:
+              logCrit('Error in %s %s chain: MAILCOW target not found, restarting container' % (family, chain))
+              quit_now = True
+              exit_code = 2
+
+            if chain_position > 0:
+              logCrit('Error in %s %s chain order: MAILCOW on position %d, restarting container' % (family, chain, chain_position))
+              quit_now = True
+              exit_code = 2
 
 def ban(address):
   global lock
@@ -190,6 +645,7 @@ def ban(address):
     logCrit('Banning %s for %d minutes' % (net, BAN_TIME / 60))
     if type(ip) is ipaddress.IPv4Address:
       with lock:
+        if backend == 'iptables':
           chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'MAILCOW')
           rule = iptc.Rule()
           rule.src = net
@@ -197,8 +653,12 @@ def ban(address):
           rule.target = target
           if rule not in chain.rules:
             chain.insert_rule(rule)
+        else:
+          ban_dict = get_ban_ip_dict(net, "ip")
+          nft_exec_dict(ban_dict)
     else:
       with lock:
+        if backend == 'iptables':
           chain = iptc.Chain(iptc.Table6(iptc.Table6.FILTER), 'MAILCOW')
           rule = iptc.Rule6()
           rule.src = net
@@ -206,6 +666,10 @@ def ban(address):
           rule.target = target
           if rule not in chain.rules:
             chain.insert_rule(rule)
+        else:
+          ban_dict = get_ban_ip_dict(net, "ip6")
+          nft_exec_dict(ban_dict)
+
     r.hset('F2B_ACTIVE_BANS', '%s' % net, cur_time + BAN_TIME)
   else:
     logWarn('%d more attempts in the next %d seconds until %s is banned' % (MAX_ATTEMPTS - bans[net]['attempts'], RETRY_WINDOW, net))
@@ -219,6 +683,7 @@ def unban(net):
   logInfo('Unbanning %s' % net)
   if type(ipaddress.ip_network(net)) is ipaddress.IPv4Network:
     with lock:
+      if backend == 'iptables':
         chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'MAILCOW')
         rule = iptc.Rule()
         rule.src = net
@@ -226,8 +691,14 @@ def unban(net):
         rule.target = target
         if rule in chain.rules:
           chain.delete_rule(rule)
+      else:
+        dict_unban = get_unban_ip_dict(net, "ip")
+        if dict_unban:
+          if(nft_exec_dict(dict_unban)):
+            logInfo(f"Unbanned ip: {net}")
   else:
     with lock:
+      if backend == 'iptables':
         chain = iptc.Chain(iptc.Table6(iptc.Table6.FILTER), 'MAILCOW')
         rule = iptc.Rule6()
         rule.src = net
@@ -235,6 +706,12 @@ def unban(net):
         rule.target = target
         if rule in chain.rules:
           chain.delete_rule(rule)
+      else:
+        dict_unban = get_unban_ip_dict(net, "ip6")
+        if dict_unban:
+          if(nft_exec_dict(dict_unban)):
+            logInfo(f"Unbanned ip6: {net}")
+
   r.hdel('F2B_ACTIVE_BANS', '%s' % net)
   r.hdel('F2B_QUEUE_UNBAN', '%s' % net)
   if net in bans:
@@ -244,6 +721,7 @@ def permBan(net, unban=False):
   global lock
   if type(ipaddress.ip_network(net, strict=False)) is ipaddress.IPv4Network:
     with lock:
+      if backend == 'iptables':
         chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), 'MAILCOW')
         rule = iptc.Rule()
         rule.src = net
@@ -257,8 +735,21 @@ def permBan(net, unban=False):
           logCrit('Remove host/network %s from blacklist' % net)
           chain.delete_rule(rule)
           r.hdel('F2B_PERM_BANS', '%s' % net)
+      else:
+        if not unban:
+          ban_dict = get_ban_ip_dict(net, "ip")
+          if(nft_exec_dict(ban_dict)):
+            logCrit('Add host/network %s to blacklist' % net)
+          r.hset('F2B_PERM_BANS', '%s' % net, int(round(time.time())))
+        elif unban:
+          dict_unban = get_unban_ip_dict(net, "ip")
+          if dict_unban:
+            if(nft_exec_dict(dict_unban)):
+              logCrit('Remove host/network %s from blacklist' % net)
+          r.hdel('F2B_PERM_BANS', '%s' % net)
   else:
     with lock:
+      if backend == 'iptables':
         chain = iptc.Chain(iptc.Table6(iptc.Table6.FILTER), 'MAILCOW')
         rule = iptc.Rule6()
         rule.src = net
@@ -272,6 +763,18 @@ def permBan(net, unban=False):
           logCrit('Remove host/network %s from blacklist' % net)
           chain.delete_rule(rule)
           r.hdel('F2B_PERM_BANS', '%s' % net)
+      else:
+        if not unban:
+          ban_dict = get_ban_ip_dict(net, "ip6")
+          if(nft_exec_dict(ban_dict)):
+            logCrit('Add host/network %s to blacklist' % net)
+          r.hset('F2B_PERM_BANS', '%s' % net, int(round(time.time())))
+        elif unban:
+          dict_unban = get_unban_ip_dict(net, "ip6")
+          if dict_unban:
+            if(nft_exec_dict(dict_unban)):
+              logCrit('Remove host/network %s from blacklist' % net)
+          r.hdel('F2B_PERM_BANS', '%s' % net)
 
 def quit(signum, frame):
   global quit_now
@@ -283,6 +786,7 @@ def clear():
   for net in bans.copy():
     unban(net)
   with lock:
+    if backend == 'iptables':
       filter4_table = iptc.Table(iptc.Table.FILTER)
       filter6_table = iptc.Table6(iptc.Table6.FILTER)
       for filter_table in [filter4_table, filter6_table]:
@@ -303,6 +807,57 @@ def clear():
         filter_table.commit()
         filter_table.refresh()
         filter_table.autocommit = True
+    else:
+      for _family in ["ip", "ip6"]:
+        is_empty_dict = True
+        json_command = get_base_dict()
+        chain_handle = get_chain_handle(_family, "filter", "MAILCOW")
+        # if no handle, the chain doesn't exists
+        if chain_handle is not None:
+          is_empty_dict = False
+          # flush chain MAILCOW
+          mailcow_chain = dict(family=_family, table="filter", name="MAILCOW")
+          mc_chain_base = dict(chain=mailcow_chain)
+          flush_chain = dict(flush=mc_chain_base)
+          json_command["nftables"].append(flush_chain)
+
+        # remove rule in forward chain
+        # remove rule in input chain
+        chains_family = [nft_chain_names[_family]['filter']['input'],
+                        nft_chain_names[_family]['filter']['forward'] ]
+
+        for chain_base in chains_family:
+          if not chain_base: continue
+
+          rules_handle = get_rules_handle(_family, "filter", chain_base)
+          if rules_handle is not None:
+            for r_handle in rules_handle:
+              is_empty_dict = False
+              mailcow_rule = dict(family=_family,
+                                  table="filter",
+                                  chain=chain_base,
+                                  handle=r_handle
+                          )
+              del_rule = dict(rule=mailcow_rule)
+              delete_rules=dict(delete=del_rule)
+              json_command["nftables"].append(delete_rules)
+
+        # remove chain MAILCOW
+        # after delete all rules referencing this chain
+        if chain_handle is not None:
+          mc_chain_handle = dict(family=_family,
+                            table="filter",
+                            name="MAILCOW",
+                            handle=chain_handle 
+                           )
+          del_chain=dict(chain=mc_chain_handle)
+          delete_chain = dict(delete=del_chain)
+          json_command["nftables"].append(delete_chain)
+
+        if is_empty_dict == False:
+          if(nft_exec_dict(json_command)):
+            logInfo(f"Clear completed: {_family}")
+
     r.delete('F2B_ACTIVE_BANS')
     r.delete('F2B_PERM_BANS')
     pubsub.unsubscribe()
@@ -354,6 +909,7 @@ def snat4(snat_target):
     time.sleep(10)
     with lock:
       try:
+        if backend == 'iptables':
           table = iptc.Table('nat')
           table.refresh()
           chain = iptc.Chain(table, 'POSTROUTING')
@@ -376,6 +932,8 @@ def snat4(snat_target):
                 chain.delete_rule(rule)
           table.commit()
           table.autocommit = True
+        else:
+          snat_rule("ip", snat_target)
       except:
         print('Error running SNAT4, retrying...')
 
@@ -395,21 +953,31 @@ def snat6(snat_target):
     time.sleep(10)
     with lock:
       try:
+        if backend == 'iptables':
           table = iptc.Table6('nat')
           table.refresh()
           chain = iptc.Chain(table, 'POSTROUTING')
           table.autocommit = False
-        if get_snat6_rule() not in chain.rules:
+          new_rule = get_snat6_rule()
-          logInfo('Added POSTROUTING rule for source network %s to SNAT target %s' % (get_snat6_rule().src, snat_target))
+          for position, rule in enumerate(chain.rules):
-          chain.insert_rule(get_snat6_rule())
+            match = all((
-          table.commit()
+              new_rule.get_src() == rule.get_src(),
+              new_rule.get_dst() == rule.get_dst(),
+              new_rule.target.parameters == rule.target.parameters,
+              new_rule.target.name == rule.target.name
+            ))
+            if position == 0:
+              if not match:
+                logInfo(f'Added POSTROUTING rule for source network {new_rule.src} to SNAT target {snat_target}')
+                chain.insert_rule(new_rule)
             else:
-          for position, item in enumerate(chain.rules):
+              if match:
-            if item == get_snat6_rule():
+                logInfo(f'Remove rule for source network {new_rule.src} to SNAT target {snat_target} from POSTROUTING chain at position {position}')
-              if position != 0:
+                chain.delete_rule(rule)
-                chain.delete_rule(get_snat6_rule())
           table.commit()
           table.autocommit = True
+        else:
+          snat_rule("ip6", snat_target)
       except:
         print('Error running SNAT6, retrying...')
 
@@ -435,7 +1003,6 @@ def isIpNetwork(address):
     return False
   return True
 
-
 def genNetworkList(list):
   resolver = dns.resolver.Resolver()
   hostnames = []
@@ -504,6 +1071,7 @@ def blacklistUpdate():
 def initChain():
   # Is called before threads start, no locking
   print("Initializing mailcow netfilter chain")
+  if backend == 'iptables':
     # IPv4
     if not iptc.Chain(iptc.Table(iptc.Table.FILTER), "MAILCOW") in iptc.Table(iptc.Table.FILTER).chains:
       iptc.Table(iptc.Table.FILTER).create_chain("MAILCOW")
@@ -528,9 +1096,15 @@ def initChain():
       rule.target = target
       if rule not in chain.rules:
         chain.insert_rule(rule)
+  else:
+    for family in ["ip", "ip6"]:
+      insert_mailcow_chains(family)
+
 
 if __name__ == '__main__':
 
+  if backend == 'nftables':
+    search_current_chains()
   # In case a previous session was killed without cleanup
   clear()
   # Reinit MAILCOW chain