IP Range and Perform Function

Hi everyone, i am currently doing on this application which is like:
1) There are 2 textboxes. All for users to enter IP address. Is like users will enter 2 IP addresses on these 2 textboxes and after that my application will check for the range of IP address in between the 2 addresses and then perform SNMPGET function to display each result that correspond to each IP address. i got this coding
protected void Button1_Click(object sender, EventArgs e) {
string First31 = TextBox1.T ...