100
Subkey Registry Value Entry
Format
Recommended Value (Decimal)
DynamicBacklogGrowthDelta
DWORD
10
EnableDynamicBacklog
DWORD
1
MinimumDynamicBacklog
DWORD
20
MaximumDynamicBacklog
DWORD
20000
DynamicBacklogGrowthDelta: (AFD DynamicBacklogGrowthDelta)
Number of connections to create when additional connections are
necessary for Winsock applications (10 recommended)
This entry appears as
MSS: (AFD DynamicBacklogGrowthDelta) Number of connections to create when
additional connections are necessary for Winsock applications (10 recommended)
in the SCE. This
setting controls the number of free connections to create when additional connections are necessary.
Be careful with this value, as a large value could lead to explosive free connection allocations.
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: (AFD DynamicBacklogGrowthDelta) Number of connections to
create when additional connections are necessary for Winsock applications (10 recommended)
to a
value of
10
. The possible values for this Registry value are:
•
0
to
0xFFFFFFFF
; default is
0
In the SCE UI, this appears as a text entry box:
•
A user defined number
•
Not Defined
Potential Impact:
Setting this value to too large a number could cause a large amount of system
resources to be assigned to allocating additional free connections that may not actually be needed.
This could lead to poor performance or a DoS condition.
EnableDynamicBacklog: (AFD EnableDynamicBacklog) Enable dynamic
backlog for Winsock applications (recommended)
This entry appears as
MSS: (AFD EnableDynamicBacklog) Enable dynamic backlog for Winsock
applications (recommended)
in the SCE. This is a global switch to enable or disable dynamic backlog.
It defaults to 0 (off), setting it to 1 enables the new dynamic backlog feature.
Vulnerability:
Socket applications may be susceptible to DoS attacks.
Countermeasure:
Configure
MSS: (AFD EnableDynamicBacklog) Enable dynamic backlog for
Winsock applications (recommended)
to a value of
Enabled
. The possible values for this Registry
value are:
•
1
or
0
; default is
0
(disabled)