Re: any way to write datalink packets?

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

kashif javed wrote:

> As pointed out by Richard Stevens in the chapter 26 of
> his book " UNIX Network Programming vol1: 2nd
> edition", pcap supports packets while reading. I want to
> ask is there any way to write datalink packets?

Libpcap 0.9.x has pcap_inject() and pcap_sendpacket() to send packets. 
WinPcap has had pcap_sendpacket() for a while.

> I mean
> if an application sends out a packet, can it be captured
> by the pcap?

That's a completely different question.

Whether pcap will see the packets sent by pcap on the same machine might 
depend on the OS you're running.  It should be able to see packets sent 
by pcap on machines on other machines, as those packets are 
indistinguishable from packets sent by other mechanisms.

> Moreover , can i use pcap for capturing packets on
> IEEE 802.11 or WLAN,

Yes, but it doesn't support it very well on OSes other than Linux and 
newer versions of the BSDs.
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