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-   -   doubt in pcap library (n/w prog) (http://www.linuxquestions.org/questions/programming-9/doubt-in-pcap-library-n-w-prog-322193/)

live_dont_exist 05-10-2005 09:42 PM

doubt in pcap library (n/w prog)
 
Hey Guys,

Am writing my first evr program using the Pcap library . Just had a couple of doubts:-

1.I only have a standalone machine with me and no NIC so can I use Pcap to listen on the loopback interface . I mean is it necessary that I need a NIC and have to listen only on the NIC's interface ; cause there might be other traffic as well over the loopback interface . If I can listen on loopback how do I avoid noise packets ; is it by using a pcap filter?

2.The pcap library needs to constantly receieve packets but it doesn't block in a loop like recvfrom() so how exactly does it work . I mean...I need to constantly listen for incoming packets so how does this work . I know I can set a time for which pcap accepts packets but what after that time interval is up ; coz there will be time left btw pcap finishing and handling the packets.

3.Do I have to call pcap ina thread or something?
for (i=0; i<4; i++)
{
pthread_create(&tid,NULL,pcap,NULL);
//code
//code
}

void pcap(){
//code.............
}

Does this actually create 4 different threads and all four threads capture packets?...Is this necessary for concurrency? I'm a bit confused as to how threads work here.

Please try n help out...thnx..this is my first pcap program so please correct if the doubts are not valid and have errors in them.

Thnx
Arvind


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