CALCUL RÉSEAU IP

 public ArrayList createNetwork(string ip, int pref)
    {
        try
        {
            // on calcul a partir de l'IP reseau : la première IP,dernière IP et l'adresse de broadcast
            string[] ipCourante = ip.Split('.');
            byte[] monIP = new byte[4];
            byte[] ipBroadcast = new byte[4];
            byte[] firstIP = new byte[4];
            byte[] ipLast = new byte[4];

            int nbIP = ((int)Math.Pow(2, (32 - pref))); // le nombre d'ip disponible pour le réseau
			
            string masque = donneMask(pref); // on va convertir le préfixe réseau en masque
            monIP[0] = System.Convert.ToByte(ipCourante[0]);
            monIP[1] = System.Convert.ToByte(ipCourante[1]);
            monIP[2] = System.Convert.ToByte(ipCourante[2]);
            monIP[3] = System.Convert.ToByte(ipCourante[3]);

            // première IP
            firstIP[0] = System.Convert.ToByte(ipCourante[0]);
            firstIP[1] = System.Convert.ToByte(ipCourante[1]);
            firstIP[2] = System.Convert.ToByte(ipCourante[2]);
            firstIP[3] = System.Convert.ToByte(System.Convert.ToByte(ipCourante[3]) + System.Convert.ToByte(1));

            mask[0] = System.Convert.ToByte(masque.Substring(0, 3));
            mask[1] = System.Convert.ToByte(masque.Substring(4, 3));
            mask[2] = System.Convert.ToByte(masque.Substring(8, 3));
            mask[3] = System.Convert.ToByte(masque.Substring(12, 3));

            // negation de bits avec '~' 255.255.255.240 => 000.000.000.015 en byte
            maskInter[0] = (byte)~mask[0];
            maskInter[1] = (byte)~mask[1];
            maskInter[2] = (byte)~mask[2];
            maskInter[3] = (byte)~mask[3];

            // dernière IP du reseau
            ipLast[0] = System.Convert.ToByte(monIP[0] | maskInter[0]);
            ipLast[1] = System.Convert.ToByte(monIP[1] | maskInter[1]);
            ipLast[2] = System.Convert.ToByte(monIP[2] | maskInter[2]);
            ipLast[3] = System.Convert.ToByte((monIP[3] | maskInter[3]) - System.Convert.ToByte(1));

            // adresse de broadcast du reseau
            ipBroadcast[0] = System.Convert.ToByte(monIP[0] | maskInter[0]);
            ipBroadcast[1] = System.Convert.ToByte(monIP[1] | maskInter[1]);
            ipBroadcast[2] = System.Convert.ToByte(monIP[2] | maskInter[2]);
            ipBroadcast[3] = System.Convert.ToByte(monIP[3] | maskInter[3]);

            ArrayList monReseau = new ArrayList();
            monReseau.Add(ip);
            monReseau.Add(firstIP[0].ToString() + "." + firstIP[1].ToString() + "." + firstIP[2].ToString() + "." + firstIP[3].ToString());
            monReseau.Add(ipLast[0].ToString() + "." + ipLast[1].ToString() + "." + ipLast[2].ToString() + "." + ipLast[3].ToString());
            monReseau.Add(ipBroadcast[0].ToString() + "." + ipBroadcast[1].ToString() + "." + ipBroadcast[2].ToString() + "." + ipBroadcast[3].ToString());
            monReseau.Add(pref);
            return monReseau;
        }
        catch (Exception ex)
        {
            return null;
        }
    }


public string donneMask(int prefix)
    {
        switch (prefix)
        {
            case 8: return "255.0.0.0";
            case 9: return "255.128.0.0";
            case 10: return "255.192.0.0";
            case 11: return "255.224.0.0";
            case 12: return "255.240.0.0";
            case 13: return "255.248.0.0";
            case 14: return "255.252.0.0";
            case 15: return "255.254.0.0";
            case 16: return "255.255.0.0";
            case 17: return "255.255.128.0";
            case 18: return "255.255.192.0";
            case 19: return "255.255.224.0";
            case 20: return "255.255.240.0";
            case 21: return "255.255.248.0";
            case 22: return "255.255.252.0";
            case 23: return "255.255.254.0";
            case 24: return "255.255.255.0";
            case 25: return "255.255.255.128";
            case 26: return "255.255.255.192";
            case 27: return "255.255.255.224";
            case 28: return "255.255.255.240";
            case 29: return "255.255.255.248";
            case 30: return "255.255.255.252";
            case 31: return "255.255.255.254";
            default: return "";
        }
    }