Re: [PATCH] fix small DoS on connect() (was Re: BUG: Unusual TCP Connect() results.)

[Thomas Graf <tgraf@xxxxxxx>]

* Herbert Xu <20050612120627.GA5858@xxxxxxxxxxxxxxxxxxx> 2005-06-12 22:06
> On Sun, Jun 12, 2005 at 01:40:39PM +0200, Willy Tarreau wrote:
> >
> > Sorry Herbert, but both RFC793 page 32 figure 9 and my Linux box disagree
> > with this statement. Look: at line 5, A rejects the SYN-ACK because the
> > ACK is wrong during the session setup.
> 
> Look at the first check inside th->ack in tcp_rcv_synsent_state_process.

Usually a continious flow of ACK+RST is used to prevent a connection
from being established, it's more reliable because even if you hit the
ISS+rcv_next window the connection attempt will still be reset.