Comparing Firewall Technologies
نویسنده
چکیده
In early January 2001, a new web page was launched. It was named Netscan, and the creators had done quite a bit of work prior to launching their Web site. Actually, the work was quite simple, but time-consuming. They had pinged the entire routed IPv4 address space; or to be more exact, they pinged every IP address ending with .0 or .255. For each PING sent, they expected one PING REPLY in return. And for each network that replied with more than one packet, they counted the number of replies and put the data into a database. All networks that did reply with more than one packet for each packet sent were considered to be an amplifier network. After pinging the entire Internet (more or less), they published on their Web site a list of the 1024 worst networks, including the e–mail address for the person responsible for the IP address and its associated network. The worst networks were those networks that gave them the highest number of replies to a single PING, or the best amplification effect. The security problem here is that it is rather easy to send a PING request to a network, using a spoofed source IP address. And when the recipient network replies, all those replies will be sent to the source address as given in the initial PING. As shown in Exhibit 1, the attacker can P A Y O F F I D E A
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