Subject: Re: pcap and ICMP messages
To: Greg Troxel <firstname.lastname@example.org>
From: =?iso-8859-1?q?J=F6rn_Seger?= <email@example.com>
Date: 09/15/2004 14:50:25
;-) I would like to have every ip-packet, I don't want to open a lot of=20
sockets, one for every protocol ...=20
I read some stevens stuff, so I came to the conclusion to use pcap.=20
PS: You are right I haven't read this manpage carefully, because i started=
this project on linux and the ip-manpage is quite different ...
Am Mittwoch, 15. September 2004 13:40 schrieben Sie:
> man ip, and search for IP_HDRINCL:
> RAW IP SOCKETS
> Raw IP sockets are connectionless, and are normally used with the
> sendto(2) and recvfrom(2) calls, though the connect(2) call may also
> be used to fix the destination for future packets (in which case the
> read(2) or recv(2) and write(2) or send(2) system calls may be used).
> If proto is 0, the default protocol IPPROTO_RAW is used for outgoing
> packets, and only incoming packets destined for that protocol are
> received. If proto is non-zero, that protocol number will be used on
> outgoing packets and to filter incoming packets.
> Outgoing packets automatically have an IP header prepended to them
> (based on the destination address and the protocol number the socket is
> created with), unless the IP_HDRINCL option has been set. Incoming packe=
> are received with IP header and options intact.
> IP_HDRINCL indicates the complete IP header is included with the data
> and may be used only with the SOCK_RAW type.
> #include <netinet/ip.h>
> int hincl =3D 1; /* 1 =3D on, 0 =3D off */
> setsockopt(s, IPPROTO_IP, IP_HDRINCL, &hincl, sizeof(hincl));
> Unlike previous BSD releases, the program must set all the fields of
> the IP header, including the following:
> ip->ip_v =3D IPVERSION;
> ip->ip_hl =3D hlen >> 2;
> ip->ip_id =3D 0; /* 0 means kernel set appropriate value */
> ip->ip_off =3D offset;
> If the header source address is set to INADDR_ANY, the kernel will
> choose an appropriate address.