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Network security device which performs MAC address translation without affecting the IP address

  • US 5,757,924 A
  • Filed: 09/18/1995
  • Issued: 05/26/1998
  • Est. Priority Date: 09/18/1995
  • Status: Expired due to Fees
First Claim
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1. A network security device which does no routing and is configured to protect at least one particular node, the node having a first media access control (MAC) address and an Internet address and which communicates via a network, comprising:

  • a. a first interface connected to the at least one particular node and having said first MAC address of the node;

    b. a second interface connected to the network and having a second MAC address, andc. a processing circuit connected to said first and second interfaces, said processing circuit;

    (1) for a packet received at said first interface from said one particular node and the packet having a header containing a source address that is the Internet address of the at least one particular node and said first MAC address of said one particular node, the circuit configured to replace the first MAC address contained in the received packet header with the second MAC address before said packet is transmitted into said network and leaving the Internet address unencrypted and its position in the packet header unchanged, and(2) for a packet received at said second interface from said network and the packet having a header containing a destination address that is the Internet address of the at least one particular node and said second MAC address of said second interface, the circuit configured to replace the second MAC address contained in the received packet header with said first MAC address of said at least one particular node before said packet is transmitted to the at least one particular node, and leaving the Internet address unencrypted and its position in the packet header unchanged.

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