A network authentication method implemented by a network authentication device deployed between a client and a server, comprising: the network authentication device receives a synchronize,SYN, data packet sent by the client, wherein the SYN data packet comprises a sequence number SEQ1 and a network parameter, wherein the network parameter comprises an Identification,ID, in an IP header of the SYN data packet and the ID is used to indicate a sequence of an IP data packet in the packets sent by the client; the network authentication device sends a synchronize acknowledge,SYN_ACK, data packet to the client in response to the SYN data packet, wherein the SYN_ACK data packet comprises an acknowledgment number ACK2, and a value of ACK2 is a value obtained by carrying out a function transformation according to the network parameter of the SYN data packet; the network authentication device receives a RESET,RST, data packet sent by the client in response to the SYN_ACK data packet, wherein the RST data packet comprises a sequence number SEQ3 or an acknowledgment number ACK3, a value of SEQ3 or ACK3 is the same as that of ACK2, and the RST data packet further comprises the same network parameter as that of the SYN data packet; the network authentication device carries out the function transformation according to the network parameter of the RST packet to obtain a check value CHK; and the network authentication device passes the authentication of the client if CHK matches the value of SEQ3 or ACK3, wherein if CHK matches the value of SEQ3 or ACK3, the network authentication device passes the authentication of the client comprises: the network authentication device passes the authentication of the client if a difference between CHK and SEQ3 or ACK3 is in a set range, wherein the set range is non-zero. the network authentication device receives a synchronize,SYN, data packet sent by the client, wherein the SYN data packet comprises a sequence number SEQ1 and a network parameter, wherein the network parameter comprises an Identification,ID, in an IP header of the SYN data packet and the ID is used to indicate a sequence of an IP data packet in the packets sent by the client; the network authentication device sends a synchronize acknowledge,SYN_ACK, data packet to the client in response to the SYN data packet, wherein the SYN_ACK data packet comprises an acknowledgment number ACK2, and a value of ACK2 is a value obtained by carrying out a function transformation according to the network parameter of the SYN data packet; the network authentication device receives a RESET,RST, data packet sent by the client in response to the SYN_ACK data packet, wherein the RST data packet comprises a sequence number SEQ3 or an acknowledgment number ACK3, a value of SEQ3 or ACK3 is the same as that of ACK2, and the RST data packet further comprises the same network parameter as that of the SYN data packet; the network authentication device carries out the function transformation according to the network parameter of the RST packet to obtain a check value CHK; and the network authentication device passes the authentication of the client if CHK matches the value of SEQ3 or ACK3, wherein if CHK matches the value of SEQ3 or ACK3, the network authentication device passes the authentication of the client comprises: the network authentication device passes the authentication of the client if a difference between CHK and SEQ3 or ACK3 is in a set range, wherein the set range is non-zero.