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===============================================================================
$Id: RAWSOCKET_NON_SEQUITUR,v 1.2 2004/01/03 20:31:00 mike Exp $
LIBNET 1.1 (c) 1998 - 2004 Mike D. Schiffman <mike@infonexus.com>
http://www.packetfactory.net/libnet
===============================================================================
Raw sockets are horribly non-standard across implementations. Here is
an incomplete list of some of the differences (corrections welcomed):
Linux 2.2+:
IP fragmentation: performed if packet is larger than MTU
IP checksum: always filled in
IP total length: always filled in
IP ID: filled in when zero
IP source address: filled in when zero
IP destination address: filled in when zero
Max packet size before kernel complains: 1500 bytes
Solaris 2.6+:
IP fragmentation bits: can't specify
IP fragmentation: performed if packet is larger than MTU
IP DF bit: always set
IP checksum: always filled in
Max packet size before kernel complains: ?
OpenBSD 2.8+:
IP fragmentation: performed if packet is larger than MTU
Max packet size before kernel complains: 8192 bytes
Solaris,
for example, has terrible support for this packet interface. Older OpenBSD
versions and recent FreeBSD versions have the BSD_BYTE_SWAP issue where
the ip_len and ip_frag fields need to be in little endian order. Linux
apparently doesn't allow for the injection of broadcast IP datagrams.
Whenever complete control over the IP header is desired, use the link
layer API.
EOF