Ethereal-users: Re: [Ethereal-users] ARP pcakets

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From: "Guy Harris" <gharris@xxxxxxxxx>
Date: Tue, 21 Sep 2004 16:22:44 -0700 (PDT)
Aradhana Sharma said:

> I am trying to get arp packets but I am not getting it, I have tried
> pinging some websites and also telnet some servers. I have dial-up
> connection

If by "I have dial-up connection" you mean that your machine is directly
connected to your ISP by a dial-up connection, then you won't get ARP
packets because you're not on a LAN, you're on a dial-up PPP link.

ARP is used on broadcast LANs such as Ethernet/Token Ring/FDDI/802.11 in
order to find, for a given IP address of a network interface on that LAN,
the MAC address for that network interface, so that packets to be sent to
that IP address can be sent to the MAC address in question.

On a PPP link, there are only two machines - your machine, and the other
machine - and there are no MAC addresses in the packet; any packet sent by
your machine will be sent to the machine on the other end of the PPP link,
so there's no need for that machine's PPP interface to have a MAC address.