Re: detection of the third tcp packet in a tcp connection setup

[Ramin Alidousti <ramin@cannon.eng.us.uu.net>]

On Thu, Jun 27, 2002 at 09:06:54PM +0100, Antony Stone wrote:

> On Thursday 27 June 2002 8:57 pm, Ramin Alidousti wrote:
> 
> > If I'm not wrong you can always send data even in SYN and SYN/ACK.
> > Like Patrick said the default options in the socket interface might
> > not do it but I thought I saw some tweaking in one of Richard Steven's
> > (god bless his soul) books to push traffic in SYN packets.
> 
> Is that an interesting way to get round packet filtering firewalls ?

Why? The fw would either block the SYN (in case of DENY) or let the
SYN and any subsequent packet through...

> Send enough data (eg an http request) in a SYN packet so that the application 
> does the dirty work for you, even if the packet filter isn't going to allow 
> the connection to get ESTABLISHED ?

Again, if the SYN gets through, it's very likely that the connection
will get ESTABLISHED.

> Or do you have to fiddle with the receiving socket too in order for it to 
> cope with this ?

Good question. dunno.

Ramin

> Antony.