Internet protocol version 4 (IPv4) packet header variation rule detection method and system
A detection method and technology of changing laws, applied in the field of detecting changes of IPv4 packet headers, can solve problems such as low data compression efficiency, and achieve the effect of solving low compression efficiency and improving compression efficiency
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Embodiment 1
[0053] see figure 1 As shown, the detection method of the IPv4 packet header change rule that the embodiment of the present invention provides may include the following steps:
[0054] Step A, calculating the difference between the curr_ip_id_offset of the current data packet and the prev_ip_id_offset of the previous data packet of the current data packet.
[0055] Record the serial number sn of the current data packet and the previous data packet of the current data packet, marked as curr_sn and prev_sn respectively; record the value ip-id of the previous data packet IP-ID of the current data packet and the current data packet, respectively marked as curr_ip_id and prev_ip_id. Then calculate the ip_id_offset value of the current data packet and the previous data packet of the current data packet according to the recorded serial number and IP-ID value, mark them as curr_ip_id_offset and prev_ip_id_offset respectively, and then do the difference to get their difference.
[00...
Embodiment 2
[0071] see figure 2 As shown, the detection method of the IPv4 packet header change rule provided by the present invention also includes the following steps:
[0072] Step B1, when the difference is greater than the preset value, switch the byte order of the IP-ID field of the IPv4 header, and recalculate the difference between the curr_ip_id_offset of the current data packet and the prev_ip_id_offset of the previous data packet of the current data packet.
[0073] Step B2, and when the difference is less than or equal to the preset value, set the current data packet NBO to 0, and return to the step C.
[0074] The specific implementation manner of this embodiment will be described below in conjunction with a specific example.
[0075] Assume that in the context, sn is 0x0004, ip-id is 0x0004, RND=0, NBO=0. For subsequent data packets, the sn of the first packet is 0x0500 and ip-id is 0x0500 according to the network order; the sn of the second packet is 0x0600 and ip-id is ...
Embodiment 3
[0090] see image 3 As shown, the detection method of the IPv4 packet header change rule provided by the present invention also includes the following steps:
[0091] Step C1, when the difference between the recalculated curr_ip_id_offset of the current data packet and the prev_ip_id_offset of the previous data packet of the current data packet is greater than the preset value after the byte order of the IP-ID field of the current data packet is switched, the Add 1 to the stability indicator of the current packet NBO.
[0092] Step D1, when the stability index of the NBO of the current data packet reaches the preset threshold value, set the current data packet RND to 1, to determine that the current data packet cannot be compressed, and select the next data packet of the current data packet as the current data packet And return to step A as described.
[0093] The preset threshold value in this step is a value that can be flexibly selected according to specific data compress...
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