On 05/ 6/10 03:48 AM, Nicolas Williams wrote:
What happens when a socket in FIN_WAIT2 is close()d, or a process exits
and a socket is closed and ends up in FIN_WAIT2? If the FIN_WAIT2 timer
is set to 2^31, what happens?
Nothing special :-) The connection can finish the close sequence
and the tcp_t transitions to TIME-WAIT state.
Suppose the process is able to exit but the socket lingers. In that
case will the lingering socket defeat resource controls?
I guess your concern is that somehow the peer goes away at the
*right* time and TCP stays in the FIN-WAIT-2 state for the
extended period of time. I further assume that you are using
this as an example of a new attack. And the goal is to create
as many lingering tcp_ts in the system as possible. For this
attack to be successful, there must be a peer co-operating. And
if you have a helpful peer, you can achieve the same thing right
now without the help of the new options. In fact, you can do
that more effectively (consuming more memory than the proposed
attack) without the use of the new option. Although the sequence
to do the above is simple, I will let the readers think about
how to do that. I will send a mail privately to explain the
steps.
As I mentioned before, if folks are not comfortable with the
value ranges, I can change that. In this case, the max can be
changed to a similar value I mentioned previously for
TCP_ABORT_THRESHOLD, which is 2 hours. Does this help?
--
K. Poon.
[email protected]
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