The mac80211 component allows for multiple virtual interfaces on the
same hardware.  Although in many/most cases the additional interfaces
must be monitor interfaces, that is still quite useful.  Since RHEL5
doesn't have the iw tool (which would normally be used to add/remove
virtual interfaces), there is currently no means to add/delete those
interfaces in RHEL5.

We carried (a version of) this patch in Fedora in the F-8 timeframe
and earlier.  I would like to see it in RHEL5.5.

BZ545121

--- linux-2.6.18.noarch/net/wireless/sysfs.c.orig	2009-12-03 12:49:01.000000000 -0500
+++ linux-2.6.18.noarch/net/wireless/sysfs.c	2009-12-03 13:12:17.000000000 -0500
@@ -34,9 +34,66 @@ static ssize_t name ## _show(struct devi
 SHOW_FMT(index, "%d", wiphy_idx);
 SHOW_FMT(macaddress, "%pM", wiphy.perm_addr);
 
+static ssize_t _store_add_iface(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t len)
+{
+	struct cfg80211_registered_device *rdev = dev_to_rdev(dev);
+	int res;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+	if (len > IFNAMSIZ)
+		return -EINVAL;
+	if (!rdev->ops->add_virtual_intf)
+		return -ENOSYS;
+
+	rtnl_lock();
+	res = rdev->ops->add_virtual_intf(&rdev->wiphy, (char*)buf,
+					  NL80211_IFTYPE_MONITOR,
+					  NULL, NULL);
+	rtnl_unlock();
+
+	return res ? res : len;
+}
+
+static ssize_t _store_remove_iface(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t len)
+{
+	struct cfg80211_registered_device *rdev = dev_to_rdev(dev);
+	int res, ifidx;
+	struct net_device *netdev;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+	if (len > IFNAMSIZ)
+		return -EINVAL;
+	if (!rdev->ops->del_virtual_intf)
+		return -ENOSYS;
+
+#if 0 /* Not in RHEL5... */
+	netdev = dev_get_by_name(&init_net, buf);
+#else
+	netdev = dev_get_by_name(buf);
+#endif
+	if (!netdev)
+		return -ENODEV;
+	ifidx = netdev->ifindex;
+	dev_put(netdev);
+
+	rtnl_lock();
+	res = rdev->ops->del_virtual_intf(&rdev->wiphy, netdev);
+	rtnl_unlock();
+
+	return res ? res : len;
+}
+
 static struct device_attribute ieee80211_dev_attrs[] = {
 	__ATTR_RO(index),
 	__ATTR_RO(macaddress),
+	__ATTR(add_iface, S_IWUGO, NULL, _store_add_iface),
+	__ATTR(remove_iface, S_IWUGO, NULL, _store_remove_iface),
 	{}
 };