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/*
*
* (C) 2013-22 - ntop.org
*
*
* 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 3 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, write to the Free Software Foundation,
* Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
#ifndef _BEHAVIOURAL_COUNTER_H_
#define _BEHAVIOURAL_COUNTER_H_
#include "ntop_includes.h"
class BehaviouralCounter {
protected:
bool is_anomaly;
u_int64_t tot_num_anomalies, last_lower, last_upper, last_value;
public:
/* Number of points to be used by the algorithm in the learning phase */
BehaviouralCounter() { is_anomaly = false, tot_num_anomalies = last_lower = last_upper = last_value = 0; }
virtual ~BehaviouralCounter() { };
/*
In Parameters:
- value The measurement to evaluate
Return:
true An anomaly has been detected (i.e. prediction < lower_bound, or prediction > upper_bound)
false The value is within the expected range
*/
virtual bool addObservation(u_int64_t value) { return(false); };
inline u_int64_t getTotNumAnomalies() { return(tot_num_anomalies); };
/* Last measurement */
inline bool anomalyFound() { return(is_anomaly); };
inline u_int64_t getLastValue() { return(last_value); };
inline u_int64_t getTotAnomalies() { return(tot_num_anomalies); };
inline u_int64_t getLastLowerBound() { return(last_lower); };
inline u_int64_t getLastUpperBound() { return(last_upper); };
};
/* ******************************** */
/* Counter based on Relative Strenght Indicator algorithm */
class RSICounter : public BehaviouralCounter {
private:
struct ndpi_rsi_struct rsi;
u_int8_t lower_pctg, upper_pctg;
public:
RSICounter(u_int16_t num_learning_observations = 10, u_int8_t lower_percentage = 25, u_int8_t upper_percentage = 75) : BehaviouralCounter() {
if(ndpi_alloc_rsi(&rsi, num_learning_observations) != 0)
throw "Error while creating RSI";
if((lower_percentage > upper_percentage) || (upper_percentage > 100))
lower_percentage = 25, upper_percentage = 75; /* Using defaults */
lower_pctg = lower_percentage, upper_pctg = upper_percentage;
}
~RSICounter() { ndpi_free_rsi(&rsi); }
bool addObservation(u_int64_t value) {
float res = ndpi_rsi_add_value(&rsi, last_value = value);
if(res == -1)
last_lower = last_upper = 0, is_anomaly = false; /* Too early */
else {
is_anomaly = ((res < lower_pctg) || (res > upper_pctg)) ? true : false;
last_lower = (u_int64_t)lower_pctg, last_upper = (u_int64_t)upper_pctg;
if(is_anomaly) tot_num_anomalies++;
}
return(is_anomaly);
}
};
/* ************************ */
/* Counter based on Double Exponential smoothing algorithm */
class DESCounter : public BehaviouralCounter {
private:
struct ndpi_des_struct des;
public:
DESCounter(double alpha = 0.9, double beta = 0.035, float significance = 0.05) : BehaviouralCounter() {
if(ndpi_des_init(&des, alpha, beta, significance) != 0)
throw "Error while creating DES";
}
bool addObservation(u_int64_t value) {
double forecast, confidence_band;
bool rc = (ndpi_des_add_value(&des, value, &forecast, &confidence_band) == 1) ? true : false;
double l_forecast = forecast-confidence_band;
double h_forecast = forecast+confidence_band;
last_value = value;
last_lower = (u_int64_t)floor(((l_forecast < 0) ? 0 : l_forecast));
last_upper = (u_int64_t)round(h_forecast+0.5);
if(rc) {
is_anomaly = ((value < last_lower) || (value > last_upper)) ? true : false;
if(is_anomaly)
tot_num_anomalies++;
return(is_anomaly);
}
return(rc);
}
};
/* ******************************** */
/* Counter based on Holt-Winters algorithm */
class HWCounter : public BehaviouralCounter {
private:
struct ndpi_hw_struct hw;
public:
HWCounter(u_int16_t num_learning_observations = 1 /* Basically smoothing without seasonality */,
double alpha = 0.7, double beta = 0.7, double gamma = 0.9)
: BehaviouralCounter() {
if(ndpi_hw_init(&hw, num_learning_observations, 1 /* additive */, alpha, beta, gamma, 0.05 /* 95% */) != 0)
throw "Error while creating HW";
}
~HWCounter() { ndpi_hw_free(&hw); }
bool addObservation(u_int64_t value) {
double forecast, confidence_band;
bool rc = ndpi_hw_add_value(&hw, last_value = value, &forecast, &confidence_band) == 1 ? true : false;
double l_forecast = forecast-confidence_band;
double h_forecast = forecast+confidence_band;
last_lower = (u_int64_t)floor(((l_forecast < 0) ? 0 : l_forecast)),
last_upper = (u_int64_t)round(h_forecast+0.5), is_anomaly = rc;
if(is_anomaly) tot_num_anomalies++;
return(is_anomaly);
}
};
#endif /* _BEHAVIOURAL_COUNTER_H_ */
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