sending MAC packets

[Charles Swiger]

On May 3, 2005, at 8:33 PM, Daniel Valencia wrote:
> I'm doing research on network-layer protocols, so I
> need a way to send packets straight into layer 2.  So
> far i've been reffered to raw sockets, but i've read
> the code and i cannot skip header checking and that
> stuff...  Is there a way to interact with the network
> if in a way that I can get network parameters (mtu,
> etc.) and send packets (specify destination mac
> address and payload)??

A non-portable mechanism for doing so is called the BPF, which is used 
by the ISC DHCP software and other programs to create packets at a low 
level.  Another option would be the libnet library, which will use the 
BPF on BSD-derived systems, but will also work on Solaris and other 
platforms which want/need to use other mechanisms to inject packets.

Be aware that the network stack may still alter packets somewhat, 
although less so than trying to go through the raw socket interface.  
This is particularly the case if hardware functionality like TXCSUM is 
enabled; you may not be able to forge the sender MAC address, either, 
although changing the destination MAC addr ought to be fine.

-- 
-Chuck