printing sequence number of a sniffed packet

Posted by scatman on Stack Overflow See other posts from Stack Overflow or by scatman
Published on 2010-03-18T16:57:33Z Indexed on 2010/03/20 12:41 UTC
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Filed under:

pcap

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packet-sniffers

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packet-capture

i am using pcap to create a packet sniffer.
i have this tcp structure:

typedef struct TSP_header{
unsigned short int sport;
unsigned short int dport;
unsigned int seqnum;
unsigned int acknum;
unsigned char reserved:4, offset:4;
unsigned int tcp_res1:4, //little-endian
tcph_hlen:4, //length of tcp header in 32-bit words
tcph_fin:1, //Finish flag "fin"
tcph_syn:1, //Synchronize sequence numbers to start a connection tcph_rst:1, //Reset flag
tcph_psh:1, //Push, sends data to the application
tcph_ack:1, //acknowledge
tcph_urg:1, //urgent pointer
tcph_res2:2; unsigned short int tcph_win;
unsigned short int tcph_chksum;
unsigned short int tcph_urgptr;
}TSP_header;

how can i print the sequence number?
shou i use htons(sequence_number)?? coz it isn't working this way!!

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