Controllo anti hacker

[Saluti]

ciao a tutti, facendo un controllo anti hacker sul sito:
http://www.hackerguardian.com mi ritrovo questo pericolo:

Security warning found on port/service "isakmp (500/udp)"

Synopsis : A VPN server is listening on the remote port. Description : The remote host seems to be enabled to do Internet Key Exchange (IKE). This is typically indicative of a VPN server. VPN servers are used to connect remote hosts into internal resources. Make sure that the use of this VPN endpoint is done in accordance with your corporate security policy.

Solution : If this service is not needed, disable it or filter incoming traffic to this port.

Risk factor : None

Di cosa si tratta?
Che cosa posso fare?

Grazie!