1 files changed, 214 insertions, 0 deletions
diff --git a/misc/freeswitch/scripts/common/perimeter.lua b/misc/freeswitch/scripts/common/perimeter.lua
new file mode 100644
index 0000000..d930514
--- /dev/null
+++ b/misc/freeswitch/scripts/common/perimeter.lua
@@ -0,0 +1,214 @@
+-- Gemeinschaft 5 module: perimeter class
+-- (c) AMOOMA GmbH 2013
+--
+
+module(...,package.seeall)
+
+
+Perimeter = {}
+
+
+function Perimeter.new(self, arg)
+  arg = arg or {}
+  object = arg.object or {}
+  setmetatable(object, self);
+  self.__index = self;
+  self.log = arg.log;
+  self.class = 'perimeter'
+  self.database = arg.database;
+  self.domain = arg.domain;
+  self.sources = {};
+
+  self.checks_available = {
+    check_frequency = self.check_frequency,
+    check_username_scan = self.check_username_scan,
+    check_bad_headers = self.check_bad_headers,
+  };
+
+  return object;
+end
+
+
+function Perimeter.setup(self, event)
+  require 'common.configuration_table';
+  local config = common.configuration_table.get(self.database, 'perimeter');
+
+  self.contact_count_threshold = 10;
+  self.contact_span_threshold = 2;
+  self.name_changes_threshold = 2;
+  self.blacklist_file = '/var/opt/gemeinschaft/firewall/blacklist';
+  self.blacklist_file_comment = '# PERIMETER_BAN - points: {points}, generated: {date}';
+  self.blacklist_file_entry = '{received_ip} udp 5060';
+  self.ban_command = 'sudo /sbin/service shorewall refresh';
+  self.ban_threshold = 20;
+  self.ban_tries = 1;
+
+  if config and config.general then
+    for key, value in pairs(config.general) do
+      self[key] = value;
+    end
+  end
+
+  self.checks = config.checks;
+  self.bad_headers = config.bad_headers;
+
+  self.log:info('[perimeter] PERIMETER - setup perimeter defense');
+end
+
+
+function Perimeter.record_load(self, event)
+  if not self.sources[event.key] then
+    self.sources[event.key] = {
+      contact_first = event.timestamp,
+      contact_last = event.timestamp,
+      contact_count = 0,
+      span_contact_count = 0,
+      span_start = event.timestamp,
+      points = 0,
+      banned = 0,
+    }
+  end
+
+  return self.sources[event.key];
+end
+
+
+function Perimeter.format_date(self, value)
+  local epoch = tonumber(tostring(value/1000000):match('^(%d-)%.'));
+  return os.date('%Y-%m-%d %X', tonumber(epoch)) .. '.' .. (value-(epoch*1000000));
+end
+
+
+function Perimeter.record_update(self, event)
+  event.record.contact_last = event.timestamp;
+  event.record.contact_count = event.record.contact_count + 1;
+  event.record.points = event.points or event.record.points;
+  event.record.span_start = event.span_start or event.record.span_start;
+  event.record.span_contact_count = (event.span_contact_count or event.record.span_contact_count) + 1;
+  event.record.users = event.users or event.record.users;
+end
+
+
+function Perimeter.check(self, event)
+  event.record = self:record_load(event);
+  -- self.log:debug('[', event.sequence, '] PERIMETER_CHECK - received: ', event.received_ip, ':', event.received_port, ', contacts: ', event.record.contact_count, ', since: ', self:format_date(event.record.contact_first), ', points: ', event.record.points);
+  
+  if event.record.banned <= self.ban_tries then
+    for check_name, check_points in pairs(self.checks) do
+      if self.checks_available[check_name] then
+        local result = self.checks_available[check_name](self, event);
+        if tonumber(result) then
+          event.points = (event.points or event.record.points) + result * check_points;
+        end
+      end
+    end
+  end
+
+  if (event.points or event.record.points) > self.ban_threshold and event.record.banned <= self.ban_tries then
+    if event.record.banned > 0 and event.record.banned == self.ban_tries then
+      self.log:warning('[', event.sequence, '] PERIMETER_BAN_FUTILE - points: ', event.points,', event: ', event.class, ', ip: ', event.received_ip, ', to: ', event.to_user, '@', event.to_host);
+    else  
+      self.log:notice('[', event.sequence, '] PERIMETER_BAN - threshold reached: ', event.points,', event: ', event.class, ', ip: ', event.received_ip, ', to: ', event.to_user, '@', event.to_host);
+      if event.record.banned == 0 then
+        self:append_blacklist_file(event);
+      end
+      self:execute_ban(event);
+    end
+        
+    event.record.banned = event.record.banned + 1;
+    event.span_start = event.timestamp;
+    event.span_contact_count = 0;
+    event.points = 0;
+  end
+
+  self:record_update(event);
+end
+
+
+function Perimeter.check_frequency(self, event)
+  if event.record.span_contact_count >= self.contact_count_threshold then
+    self.log:info('[', event.sequence, '] PERIMETER_FREQUENCY_CHECK - contacts: ', event.record.span_contact_count, ' in < ', (event.timestamp - event.record.span_start)/1000000, ' sec, threshold: ', self.contact_count_threshold, ' in ', self.contact_span_threshold, ' sec');
+    event.span_contact_count = 0;
+    event.span_start = event.timestamp;
+    return 1;
+  elseif (event.timestamp - event.record.span_start) > (self.contact_span_threshold * 1000000) then    
+    event.span_contact_count = 0;
+    event.span_start = event.timestamp;
+  end
+end
+
+
+function Perimeter.check_username_scan(self, event)
+  if not event.to_user then
+    return;
+  end
+
+  if not event.record.users then
+    event.users = { event.to_user };
+    return;
+  end
+
+  if #event.record.users >= self.name_changes_threshold then
+    self.log:info('[', event.sequence, '] PERIMETER_USER_SCAN - user names: ', #event.record.users, ', threshold: ', self.name_changes_threshold);
+    event.users = {};
+    return 1;
+  else
+    for index=1, #event.record.users do
+      if event.record.users[index] == tostring(event.to_user) then
+        return
+      end
+    end
+
+    if not event.users then
+      event.users = event.record.users or {};
+    end
+    table.insert(event.users, tostring(event.to_user));
+  end
+end
+
+
+function Perimeter.check_bad_headers(self, event)
+  local points = nil;
+  for name, pattern in pairs(self.bad_headers) do
+    local success, result = pcall(string.find, event[name], pattern);
+    if success and result then
+      self.log:info('[', event.sequence, '] PERIMETER_BAD_HEADERS - ', name, '=', event[name], ' ~= ', pattern);
+      points = (points or 0) + 1;
+    end
+  end
+
+  return points;
+end
+
+
+function Perimeter.append_blacklist_file(self, event)
+  local blacklist = io.open(self.blacklist_file, 'a');
+  if not blacklist then
+    self.log:error('[', event.sequence, '] PERIMETER_APPEND_BLACKLIST - could not open file: ', self.blacklist_file);
+    return false;
+  end
+
+  event.date = self:format_date(event.timestamp);
+
+  if self.blacklist_file_comment then  
+    blacklist:write(self:expand_variables(self.blacklist_file_comment, event), '\n');
+  end
+
+  self.log:debug('[', event.sequence, '] PERIMETER_APPEND_BLACKLIST - ip: ', event.received_ip);
+  blacklist:write(self:expand_variables(self.blacklist_file_entry, event), '\n');
+  blacklist:close();
+end
+
+
+function Perimeter.execute_ban(self, event)
+  local command = self:expand_variables(self.ban_command, event);
+  self.log:debug('[', event.sequence, '] PERIMETER_EXECUTE_BAN - ip: ', event.received_ip, ', command: ', command);
+  local result = os.execute(command);
+end
+
+
+function Perimeter.expand_variables(self, line, variables)
+  return (line:gsub('{([%a%d%._]+)}', function(captured)
+    return variables[captured] or '';
+  end))
+end