public void progress() {
        this.iterationCounter++;
        for (int i = 0; i < this.computers.length; i++) {
            for (int j = 0; j < this.computers.length; j++) {
                // check connection and infection for virus attack possibility
                if ((this.connection[i][j] == 1) && (this.computers[i].isInfected() || this.computers[j].isInfected())) {
                    if (this.computers[i].isInfected()) {
                        this.computers[j].attack(this.iterationCounter);
                    } else {
                        this.computers[i].attack(this.iterationCounter);
                    }
                }
            }
        }       
    }