HP 6125G HP 6125G & 6125G/XG Blade Switches Security Configuration Gui - Page 265
Configuring URPF, Overview, How URPF works
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Configuring URPF The term "router" in this feature refers to both routers and Layer 3 switches. Overview Unicast Reverse Path Forwarding (URPF) protects a network against source spoofing attacks, such as denial of service (DoS) and distributed denial of service (DDoS) attacks. Attackers launch source spoofing attacks by creating packets with forged source addresses. For applications using IP-address-based authentication, this type of attack allows unauthorized users to access the system in the name of authorized users, or to even access the system as the administrator. Even if the attackers cannot receive any response packets, the attacks are still disruptive to the attacked target. Figure 80 Attack based on source address spoofing As shown in Figure 80, an attacker on Router A sends the server (Router B) requests with a forged source IP address 2.2.2.1, and Router B sends response packets to IP address 2.2.2.1 (Router C). Consequently, both Router B and Router C are attacked. URPF can prevent such attacks. How URPF works URPF does not check multicast packets. URPF works in the steps, as shown in Figure 81. 255
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