Very Computer

I write a simple program to set my NIC in promiscuous mode and capture
all tcp or udp datagrams.

The following is taken from linux man page raw(7):
       An  IPPROTO_RAW socket is send only.  If you really want to
receive all IP packets use a packet(7) socket with the ETH_P_IP
protocol. Note that packet sockets don't reassemble IP fragments,
unlike raw sockets.

Does it mean that I need to write codes myself to reassemble ip packet
if it's fragmented? And if I want to receive all TCP segments or UDP
datagrams, is it feasible to use raw socket instead of packet socket
and set the protocol to IPPROTO_TCP or IPPROTO_UDP?

Thanks in advance for any help.

Quote:>I write a simple program to set my NIC in promiscuous mode and capture
>all tcp or udp datagrams.

>The following is taken from linux man page raw(7):
>       An  IPPROTO_RAW socket is send only.  If you really want to
>receive all IP packets use a packet(7) socket with the ETH_P_IP
>protocol. Note that packet sockets don't reassemble IP fragments,
>unlike raw sockets.

>Does it mean that I need to write codes myself to reassemble ip packet
>if it's fragmented? And if I want to receive all TCP segments or UDP
>datagrams, is it feasible to use raw socket instead of packet socket
>and set the protocol to IPPROTO_TCP or IPPROTO_UDP?

>Thanks in advance for any help.

Why don't you use ethereal or tcpdump.  They've already written all
that stuff.

Best,
Leigh Bassett
Software architect and embedded systems guru.
Registered Linux user #307936

Quote:

> Why don't you use ethereal or tcpdump.  They've already written all
> that stuff.

I have already known that. My purpose is to learn something about
tcp/ip by writing some codes myself.

Quote:> Best,
> Leigh Bassett
> Software architect and embedded systems guru.
> Registered Linux user #307936

You may want to use 'pcap' and 'libnet'.

Quote:

> Why don't you use ethereal or tcpdump.  They've already written all
> that stuff.

I have already known that. My purpose is to learn something about
tcp/ip by writing some codes myself.

Quote:> Best,
> Leigh Bassett
> Software architect and embedded systems guru.
> Registered Linux user #307936