salut

L'explication de Norton suit, en anglais...
Je n'ai pas le temps de traduire, mais ça n'est pas grave et il n'y a rien à craindre (Norton bloque une activité qui ne respecte pas les règles du net = surement bénin, faux positif)
Règle Norton pour qu'il bloque "silencieusement" (non affichage des messages)

<ital>Invalid UDP Destination Port
Severity: Low
This attack poses a minor threat. Corrective action may not be possible or is not required.
Attack Category: Suspicious Activity
Anomalous network conditions or traffic patterns. A suspicious activity signature, for example, might detect two systems with identical IP addresses, a condition that indicates an attempted IP spoofing attack.
Description
This attack signature detects packets that have a UDP destination port of 0. 0 is an invalid value for the UDP destination port and must not be used.
Additional Information
Attackers sometime send UDP packets with a destination port of 0 as means of fingerprinting/profiling your operating system.
False Positive
</ital>

@+