permission for socket access

[Rain]

Hi, i only need to make the scoket access unrestricted and nothing else. How
do i do this in an xml which i will be using in adding a permission set using
caspol?

<PermissionSet class="System.Security.NamedPermissionSet" version="1">
<Permission class="System.Net.SocketPermissionAttribute, mscorlib,
Ver=2000.14.1812.10, SN=03689116d3a4ae33" version="1">
<Unrestricted />
</Permission>
</PermissionSet>

This is my sample code but it doesnt work, it tells me that
System.Net.SocketPermissionAttribute is not valid. PLease, i need help.
Anyhelkp would be appreciated. Thank you so much in advance.