Re: [Programming] kernel level grab packet

From: Tauno Voipio (tauno.voipio_at_iki.fi.NOSPAM.invalid)
Date: 01/31/04 

Date: Sat, 31 Jan 2004 16:35:49 GMT

Shin wrote:

>>>Anyone knows good documents/toturial/material for me?
>>
>>www.netfilter.org is the official netfilter/iptables site.
>>www.tldp.org is the main Linux documentation repository.
>>
> Well, I might misuse the word 'guard' before.
> I am trying to make it clear here.
>
> What I want is to implement a program underlying the existing
> internet services/applications such as ftp, www, or even higher
> level software. Before going to the higher level, packets will
> be caught by the program, named P here, and then go where they
> should go. Likewise, before going to the physical level, packets
> will be caught by P. Then go to the internet.
>
> P may do some things on packets, like hashing the contents,
> delaying (not dropping) for a while, and etc. Besides, the
> one funtionality I need in P is that P can change packet's
> destination without higher level application's notice.
>
> For example, suppose there are two (or more) any kind of servers,
> and one client application C. C only knows one of them, but P
> knows all. Under some circumstances, I may hope C's packets go to
> the server which C doesn't know. Now, it's time P to work.
> I may even add some condtions in P so that P can pick up a server to
> connect to automatically.
> Combining all the functionalities I mentioned above, I guess kernel
> level can meet my need without losing flexibility, since I may
> add more functions on P in future.

Would you please read the previous response and check the Linux
packet filtering documentation? It' exactly doing what you're
trying to describe, and much more.

Some good tutorial texts about basic TCP/IP networking may
also be in order.

There is no idea in trying to re-invent a wheel.

There are many other programming tasks, even in the kernel area.

Tauno Voipio
tauno voipio @ iki fi

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