97
DisableIPSourceRouting: IP source routing protection level (protects
against packet spoofing)
This entry appears as
MSS: IP source routing protection level (protects against packet spoofing)
in the
SCE. IP source routing is a mechanism allowing the sender to determine the IP route that a datagram
should take through the network.
Vulnerability:
An attacker could use source routed packets to obscure their identity and location.
Source routing allows a computer sending a packet to specify the route it takes.
Countermeasure
:
Configure
MSS: IP source routing protection level (protects against packet
spoofing)
to a value of
Highest protection, source routing is completely disabled.
The possible values
for this Registry value are:
•
0, 1,
or
2
; default is
0
(source routed packets are acknowledged)
In the SCE UI, the following list of options appears:
•
No additional protection, source routed packets are allowed
•
Medium, source routed packets ignored when IP forwarding is enabled.
•
Highest protection, source routing is completely disabled
•
Not Defined
Potential Impact:
Setting this value to 2 will cause all incoming source routed packets to be
dropped.
T
cpMaxConnectResponseRetransmissions: SYN-ACK retransmissions
when a connection request is not acknowledged
This entry appears as
MSS: SYN-ACK retransmissions when a connection request is not acknowledged
in the SCE. This parameter determines the number of times that TCP retransmits a SYN before
aborting the attempt. The retransmission time-out is doubled with each successive retransmission in a
given connect attempt. The initial time-out value is three seconds.
Vulnerability:
In a SYN flood attack, the attacker sends a continuous stream of SYN packets to a
server, and the server leaves the half-open connections open until it is overwhelmed and no longer is
able to respond to legitimate requests.
Countermeasure:
Configure
MSS: SYN-ACK retransmissions when a connection request is not
acknowledged
to a value of
3 seconds
, half-open connections dropped after nine seconds. The
possible values for this Registry value are:
•
0-0xFFFFFFFF
; default is
2
In the SCE UI, the following list of options appears, corresponding to a value of 0, 1, 2, and 3
respectively:
•
No retransmission, half-open connections dropped after 3 seconds
•
3 seconds, half-open connections dropped after 9 seconds
•
3 & 6 seconds, half-open connections dropped after 21 seconds
•
3, 6, & 9 seconds, half-open connections dropped after 45 seconds
•
Not Defined