2.2.1.1 NAP-SoH Option
The NAP-SoH vendor-specific option encapsulates the SoH token for transmission to the DHCP server. This option is also used to determine whether the DHCP server is NAP-capable.
This vendor-specific option MUST be encapsulated inside option 43, as specified in [RFC2132] section 8.4.
The NAP-SoH option is defined as follows.
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2 |
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3 |
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Vendor-Specific_Option_Code |
Vendor-Specific_Option_Length |
Vendor-Specific_Option_Data (variable) |
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Vendor-Specific_Option_Code (1 byte): This MUST be 220 (0xDC).
Vendor-Specific_Option_Length (1 byte): Length in bytes of the Vendor-Specific_Option_Data field.
Vendor-Specific_Option_Data (variable): This MUST contain one of the following:
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No Data: A NAP-SoH option of Vendor-Specific_Option_Length zero is sent by the client in the DHCPDISCOVER message to determine whether NAP is enabled on the server. However, Vendor-Specific Option 43 never has a length of zero. In the DHCPDISCOVER message, the Vendor-Specific Option 43 has a length of 134, containing Option 222 (0xDE) for NAP-CoID, whose length is 130, and Option 220 (0xDC), whose length is 0. Option 220 (0xDC) with a length of 0 is included by the client in order to probe whether NAP is enabled on the server. NAP-CoID (option 222 (0xDE)) contains a randomly generated correlation ID to enable end-to-end correlation of NAP transaction between the DHCP client and the DHCP server and is defined in section 2.2.1.3.
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Zero of length 1: One byte with value 0x00 sent by the client in DHCPREQUEST or DHCPINFORM messages to check whether NAP has been enabled on the server.
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Data of length 3: With data as string "NAP" in network byte order, sent by the server in DHCPOFFER or DHCPACK messages to indicate to the client that NAP is enabled on the server.
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System SoH: Binary data of variable length, as defined in [TNC-IF-TNCCSPBSoH], representing the client's health state, sent by the client in DHCPREQUEST messages.
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SoH-Response: Binary data of variable length, as defined in [TNC-IF-TNCCSPBSoH], representing the client's quarantine state, sent by the server in DHCPACK messages.