406
Enabling Naptha attack protection
Naptha attacks are similar to the SYN Flood attacks. Attackers can perform Naptha attacks by using the
six TCP connection states (CLOSING, ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, LAST_ACK, and
SYN_RECEIVED), and SYN Flood attacks by using only the SYN_RECEIVED state.
Naptha attackers control a huge amount of hosts to establish TCP connections with the server, keep
these connections in the same state (any of the six), and request for no data in order to exhaust the
memory resource of the server. As a result, the server cannot process normal services.
Protection against Naptha attacks reduces the risk of such attacks by accelerating the aging of TCP
connections in a state. After the feature is enabled, the device (serving as a TCP server) periodically
checks the number of TCP connections in each state. If the device detects that the number of TCP
connections in a state exceeds the maximum number, it considers that a Naptha attack occurs, and it
accelerates the aging of TCP connections in this state. The device stops accelerating the aging of TCP
connections when the number of TCP connections in the state is less than 80% of the maximum number
(1 at least).
To enable protection against Naptha attack:
To do...
Command...
Remarks
1.
Enter system view.
system-view
—
2.
Enable the protection
against Naptha attack.
tcp anti-naptha enable
Required.
Disabled by default.
3.
Configure the maximum
number of TCP
connections in a state.
tcp state
{
closing
|
established
|
fin-
wait-1
|
fin-wait-2
|
last-ack
|
syn-
received
}
connection-number
number
Optional.
5 by default.
If the maximum number of TCP
connections in a state is 0, the aging
of TCP connections in this state are
not accelerated.
4.
Configure the TCP state
check interval.
tcp timer check-state
timer-value
Optional.
30 seconds by default.
Displaying and maintaining TCP and ICMP attack
protection
To do…
Command…
Remarks
Display current TCP connection state.
display tcp status
[
|
{
begin
|
exclude
|
include
}
regular-expression
]
Available in any view