Re: how to determine port numbering

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

On Jun 9, 2011, at 10:22 PM, rajath kumara wrote:

> I am working with ostinato for past 1 week, and found it great.

By "ostinato" do you mean

        http://code.google.com/p/ostinato/

?

> currently i'm facing problems with port numbering, right now i have 6
> ports( 4 D-link ethernet adapters and 2 Netgear , Ethernet PCI
> adapter ) . when i connect  cables , ports are getting connected ( im
> able to transmit, receicve the frames ), but problem is, I'm not able
> to figure out the way port numbers are assigned.
>
> for example , like i mentioned i have 6 ports now, when i connect a
> cable to last port , port 3 is activated, if i connect cable to 1st
> port in my system, port 2 gets activated in ostinato.

The page says

        Runs on Windows, Linux, BSD and Mac OS X (Will probably run on other platforms also with little or no 
modification but this hasn't been tested)

libpcap/WinPcap do not have any notion of "port numbers" for network adapters.  tcpdump/WinDump do, but all they're 
doing is getting a list of network adapters from libpcap/WinPcap and using ordinal numbers in that list.  I don't know 
whether that's what Ostinato is doing or not.

The list of network adapters libpcap/WinPcap supplies is, except for loopback adapters on those platforms where libpcap 
supports them, in the order in which the OS supplies them to libpcap or whatever order the WinPcap driver gets them 
from the OS. (Loopback adapters are sorted to the end of the list.)

There is no simple rule to determine the order for the list the OS supplies.  This list:

        http://www.iniqua.com/wp-content/uploads/2010/12/ihaveadream.png

is on a Mac OS X machine; the first interface is the built-in Ethernet, the second interfaces is the FireWire adapter, 
the next three are probably add-on Ethernets, and the last one is the loopback adapter.  On my Mac, also running OS X, 
the list is en0, fw0, ppp0, utun0, en1, lo0, with the build-in Ethernet first, the FireWire adapter second, a PPP 
adapter for my VPN connection to work third, a tunnel interface of some sort fourth, the AirPort Wi-Fi adapter fifth, 
and the loopback adapter last.  If I disconnect the VPN, the list changes to en0, fw0, utun0, en1, lo0.-
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