[client] Skip down interfaces in network address collection for posture checks (#5768)

client/firewall/uspfilter/localip.go

@@ -144,6 +144,8 @@ func (m *localIPManager) UpdateLocalIPs(iface common.IFaceMapper) (err error) {
 	if err != nil {
 		log.Warnf("failed to get interfaces: %v", err)
 	} else {
+		// TODO: filter out down interfaces (net.FlagUp). Also handle the reverse
+		// case where an interface comes up between refreshes.
 		for _, intf := range interfaces {
 			m.processInterface(intf, &newIPv4Bitmap, ipv4Set, &ipv4Addresses)
 		}

client/system/info.go

@@ -153,6 +153,9 @@ func networkAddresses() ([]NetworkAddress, error) {
 
 	var netAddresses []NetworkAddress
 	for _, iface := range interfaces {
+		if iface.Flags&net.FlagUp == 0 {
+			continue
+		}
 		if iface.HardwareAddr.String() == "" {
 			continue
 		}