Helper for IPv4 operations

P.S.: Standart IPAddress class has "Adress" property for getting IP as "long" that is marked as deprecated so I relize it by my self.

        static class IPOperations
        {
            /// <summary>
            /// Convert IP address to unsigned int value
            /// </summary>
            public static UInt32 ToUInt(System.Net.IPAddress ip)
            {
                return ToUInt(ip.GetAddressBytes());
            }

            /// <summary>
            /// Convert IP address to unsigned int value
            /// </summary>
            public static UInt32 ToUInt(byte[] bip)
            {
                if (bip == null) throw new ArgumentNullException();
                if (bip.Length < 4) 
                    throw new FormatException(
                        "IPOperations: parameter byte[] ip must have 4 or more elements.");
                return (uint)(bip[3] | (bip[2] << 8) | (bip[1] << 16) | (bip[0] << 24));
            }

            /// <summary>
            /// Convert IP address to unsigned int value
            /// </summary>
            /// <exception cref="System.ArgumentNullException"></exception>
            /// <exception cref="System.FormatException"></exception>
            public static UInt32 ToUInt(string ip)
            {
                return ToUInt(System.Net.IPAddress.Parse(ip));
            }

            /// <summary>
            /// Convert IP to string
            /// </summary>
            public static string ToString(long ip)
            {
                return ToString(ToByte((uint)ip));
            }

            /// <summary>
            /// Convert IP to string
            /// </summary>
            public static string ToString(byte[] ip)
            {
                if (ip == null) throw new ArgumentNullException();
                if (ip.Length < 4) 
                    throw new FormatException(
                        "IPOperations: parameter byte[] ip must have 4 or more elements.");
                return ip[0] + "." + ip[1] + "." + ip[2] + "." + ip[3];
            }

            /// <summary>
            /// Convert IP to byte array
            /// </summary>
            public static byte[] ToByte(UInt32 ip)
            {
                byte[] res = new byte[4];
                res[3] = (byte)ip;
                ip = ip >> 8;
                res[2] = (byte)ip;
                ip = ip >> 8;
                res[1] = (byte)ip;
                ip = ip >> 8;
                res[0] = (byte)ip;
                return res;
            }

            /// <summary>
            /// Increment ip address
            /// </summary>
            /// <param name="ip">ip
            public static System.Net.IPAddress Inc(System.Net.IPAddress ip)
            {
                return new System.Net.IPAddress(ToUInt(ip) + 1);
            }
            public static System.Net.IPAddress Inc(long ip)
            {
                return new System.Net.IPAddress(ip + 1);
            }

            /// <summary>
            /// subtraction ip's
            /// </summary>
            /// <param name="ip1">minuend
            /// <param name="ip2">subtrahend
            /// <returns> = ip1 - ip2</returns>
            public static long Sub(System.Net.IPAddress ip1, System.Net.IPAddress ip2)
            {
                return ToUInt(ip1) - ToUInt(ip2);
            }
        }