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-rw-r--r--misc/freeswitch/scripts/common/perimeter.lua214
1 files changed, 214 insertions, 0 deletions
diff --git a/misc/freeswitch/scripts/common/perimeter.lua b/misc/freeswitch/scripts/common/perimeter.lua
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+++ b/misc/freeswitch/scripts/common/perimeter.lua
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+-- 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