Add rules support
diff --git a/openstack/compute/v2/extensions/secgroups/urls.go b/openstack/compute/v2/extensions/secgroups/urls.go
index 9c1859f..37a9048 100644
--- a/openstack/compute/v2/extensions/secgroups/urls.go
+++ b/openstack/compute/v2/extensions/secgroups/urls.go
@@ -4,6 +4,7 @@
 
 const (
 	secgrouppath = "os-security-groups"
+	rulepath     = "os-security-group-rules"
 )
 
 func resourceURL(c *gophercloud.ServiceClient, id string) string {
@@ -17,3 +18,7 @@
 func listByServerURL(c *gophercloud.ServiceClient, serverID string) string {
 	return c.ServiceURL(secgrouppath, "servers", serverID, secgrouppath)
 }
+
+func rootRuleURL(c *gophercloud.ServiceClient) string {
+	return c.ServiceURL(rulepath)
+}