List<int> parts = new List<int>();
Random r = new Random((int)DateTime.Now.Ticks);
for(int i = 0; i < 4; i++){
int s = r.Next(0, 256);
if(i == 0){
int[] blackList = new[]{0, 10, 168, 192};
while(blackList.Contains(s))
s = r.Next(1, 256);
}
parts.Add(s);
}
return string.Join(".", parts);