Switch market in recent years has maintained a high growth, market size in 2009 is expected to reach 1.51 billion U.S. dollars. Switches in an enterprise network plays an important role, often the core of the network, the status of hackers and viruses to make it the focus of raging, for the protection of their network security, enterprises need to switch on the LAN to conduct a comprehensive vulnerability understanding. The following are the five attacks using the switch means vulnerability.
Spanning Tree Attack Spanning Tree Protocol (STP) can prevent the exchange of environment has redundant circuit. If the network has a loop, congestion will become unbearable to broadcast storms caused by MAC tables are inconsistent, and finally to network collapse.
All switches are used by STP bridge protocol data unit (BPDU) to share information, BPDU every two seconds to send one. When the switch sends BPDU, which contains a bridge ID of the label name, the bridge ID combines configurable priority number (default is 32768) and the switch MAC address basic. Switches can send and receive these BPDU, to determine which switch has the lowest bridge ID, has the lowest bridge ID of the switch as the root bridge (rootbridge).
Root bridge is like a small town in the community grocery store, every town needs a grocery store, and every citizen need to determine the best route to reach the grocery store. More than the length of the route best route will not be used unless there blocking the main channel.
Root bridge work very similar. Each of the other switches back to the root bridge determine the best route to embark upon a basis of cost, and such costs are based on the value assigned to the bandwidth. If you find any other route out of block mode does not form a loop (for example if the main line problems), they will be set to blocking mode.
Malicious hackers use STP’s work to launch a denial of service (DoS) attacks. If a malicious hacker to a computer connected to more than one switch, and then send a low bridge ID designed BPDU, the switch can be deceiving, it thought it was the root bridge, which will lead to STP re-convergence (reconverge), causing circuit, leading to network collapse.
MAC table flooding attacks Switch works is: when the frame entered the switch to record the source MAC address, the MAC address of that frame into the port-related, so after leading the MAC address of the information flow will only be sent through the port. This can improve bandwidth utilization, because the information flow do not need to send out from all the ports, but only those received from the port needs to send out.
MAC address stored in the content addressable memory (CAM) which, CAM is a 128K size of reserved memory, specially used to store the MAC address for quick inquiries. If a malicious hacker to send a large number of data packets to the CAM, can lead to various parts of the switch started to send large numbers of information flow, which buried a hidden switch or even lead to denial of service attack in the crash.
ARP attack ARP (AddressResolutionProtocol) deception is used for session hijacking attacks in the common way. Address Resolution Protocol (ARP) using Layer 2 MAC address to map the physical Layer 3 logical IP address, if the device is known IP address, but do not know the MAC address of the requested host, it will send the ARP request. Broadcast ARP request is usually sent to all hosts can be received.
Malicious hacker can send cheated ARP replies sent to another host for the flow of information. Jimmy also assume that hackers on the network, he tried to get sent to the legitimate user’s information flow, Jimmy cheat hacker ARP response, claims to be IP address of 10.0.0.55 (MAC address 05-1C-32-00-A1-99 ) master, legitimate users will use the same MAC address to respond. The result is that the switch in the MAC with the surface of the table with the MAC address of the relevant two-port, sent to the MAC address simultaneously all the frames are sent to the legitimate users and hackers Jimmy.
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