Assuming LDAPv3, but it's easy enough to change that. This is anonymous, unencrypted LDAPv3 LdapConnection creation.
private const string TargetServer = "ldap.example.com";
Actually create the connection with three parts: an LdapDirectoryIdentifier (the server), and NetworkCredentials.
// Configure server and credentials
LdapDirectoryIdentifier identifier = new LdapDirectoryIdentifier(TargetServer);
NetworkCredential creds = new NetworkCredential();
LdapConnection connection = new LdapConnection(identifier, creds)
{
AuthType=AuthType.Anonymous,
SessionOptions =
{
ProtocolVersion = 3
}
};
To use the connection, something like this would get people with the surname Smith
SearchRequest searchRequest = new SearchRequest("dn=example,dn=com", "(sn=Smith)", SearchScope.Subtree,null);