Re: Devices and adresses in libpcap

[Guy Harris <guy () alum mit edu>]

David Rosal wrote:

> As far as I know, each network interface (for example eth0), can have
> different adresses, because in pcap_findalldevs(), a pcap_if_t does not hold
> a single pcap_addr_t but a linked list of all  addresses for each
> interface/device.

Yes, it can have multiple addresses, and, yes, pcap_findalldevs() 
returns all of the ones it can get.

> But pcap_lookupnet() only returns one address for a given
> device.

Yes, it returns only one address.

> So the question is: If pcap_lookupnet() only returns one address
> (and its netmask), does it mean that it discards all the other addresses
> for that device?

Yes, it discards any other addresses for the interface.  On UN*X, it 
returns the IP address and mask you get from an SIOCGIFADDR and 
SIOCGIFNETMASK ioctl, which is probably the first of the IP addresses; 
on Windows, it gets the entire set of address/mask pairs and returns 
only the first one.
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