*Note: Port redirection can be very difficult to detect and almost impossible to
prevent because of the weaknesses with all firewalls; after all, ???They cannot
prevent what they must allow.??? Because of this weakness an attacker can use
port redirection through any allowed port through the firewall. Internet firewalls
commonly allow ports 21, 53, 80, 443, and so forth.
Chapter 11
Denial-of-Service (DoS)
Denial-of-Service (DoS)
645
Lab 91: Denial-of-Service ??“??“ Land Attack
DoS Land Attack: Land Attack
Prerequisites:
None
Countermeasures:
Secure access control lists (ACLs), Bastion servers/
workstations, ingress filtering
Description:
Sending a packet with the synchronize (SYN) flag set to a
target where the source IP is set to match the actual target??™s IP causes
the system to try to respond to itself, causing the system to lock up.
Procedure:
Install RafaleX, set parameters, and execute against the target.
Verify with the packet sniffer.
Install the RafaleX application as outlined in Lab 48.
Install the Ethereal application as outlined in Lab 41.
Open the Ethereal application and start capturing data (refer to Lab 41).
Open the RafaleX application by clicking on the
RafaleX.exe
icon.
The RafaleX application will start.
646
Practical Hacking Techniques and Countermeasures
Set the
Source IP
address to the
IP Address
of the target. Set the
Source
Port
to
80
. (We know it is a Web server.
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