A company has implemented PPTP as a VPN solution. Which of the following ports would need to
be opened on the firewall in order for this VPN to function properly? (Select TWO).
A.
UDP 1723
B.
TCP 500
C.
TCP 1723
D.
UDP 47
E.
TCP 47
Explanation:
A PPTP tunnel is instantiated by communication to the peer on TCP port 1723. This TCP
connection is then used to initiate and manage a second GRE tunnel to the same peer. The PPTP
GRE packet format is non-standard, including an additional acknowledgement field replacing the
typical routing field in the GRE header. However, as in a normal GRE connection, those modified
GRE packets are directly encapsulated into IP packets, and seen as IP protocol number 47.