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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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:

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.

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.

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.

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.

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.

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