tcpdump mailing list archives

Libpcap question


From: "Jacky Buyck" <jacky.buyck () wanadoo fr>
Date: Fri, 16 Apr 2004 00:17:54 +0200

Hi all.

I'm trying to play with libpcap to make a little tool and it the same
way to make a little tutorial on it.
I'm facing a question regarding pcap_if_t structure. 
This last one is composed of :
        - pcap_if *next (to implement the link between list's element) ;
        - char    *name (for the interface name) ;
        - ...
        - pcap_addr *addresses ;

This last one, if I've correctly understand handle all the addresses
that can be use on an interface.
For the moment I simply want to list all the interface available through
libpcap and for each one list all the available addresses on it.

I've try with the following code :


//======================================================================
======================
pcap_if_t *lst_dev = 0x00
ret = pcap_findalldevs(&lst_dev,errbuf);

if (ret == -1)
        ...

//Parse the list of interface
pcap_if_t *ptr_dev = lst_dev;

while (ptr_dev->next)
{
        printf("Name : %s\n",ptr_dev->name);
        
        //For each interface, list the addresses available
        pcap_addr_t *ptr = ptr_dev->addresses;
        while(ptr->next)
                {
                        char *tmp = inet_ntoa(((struct
sockaddr_in*)(ptr->addr))->sin_addr);
                        printf("Address : %s\n",tmp);
                        ptr = ptr->next;
                }
}
//======================================================================
======================


The problem is that I obtain something completely différent from my
config :

Ouput of the program is :
Name : wlan0
        Address : 20.0.0.1
Name : eth0
        Address : 192.168.0.1
        Address : 30.0.0.1
Name : eth1
        Address : 10.0.0.1
Name : eth2
Name : Any
        Address : 127.0.0.1



My config is :
        wlan0 :         10.0.10.1
        eth0 :          20.0.0.1
        eth1 :  192.168.0.1 and 30.0.0.1
        eth2 :          10.0.0.1


What I've misunderstand ?????
I'm using libpcap 0.7.2 under RH 9.0

Thanks.

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