hi
i downloaded a sniffer from the net. i could not understand the foll lines.
ip=(struct iphdr *)(((unsigned long)&ep.ip)-2);<== (doubt)
tcp=(struct tcphdr *)(((unsigned long)&ep.tcp)-2);
ep is a variable to the structure of this type
struct ethpkt {
struct ethdhr eth;
struct iphdr ip;
struct tcphdr tcp;
};
the structure is read from the socket like this
x=read(s, (struct etherpacket *)&ep, sizeof(ep));
iam not able to understand why is that subtraction (-2)
i've built a code, using this as the base (without knowing, why this-2
itself). i dont want to change the code. So please explain to me this. it
would be of great help
thanks in advance
bye
rajesh balan
NOTE :
1 - the code i've written over this is working well.
2 - iam sending the code as an attachment(sniffer.c)
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