lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Tue, 17 Apr 2007 16:13:06 +1000
From:	Philip Craig <philipc@...pgear.com>
To:	Sebastian Kuzminsky <seb@...hlab.com>
Cc:	netdev@...r.kernel.org
Subject: Re: bug in tcp?

Sebastian Kuzminsky wrote:
> Weird.  Why does sending a message from the client make it go again?

The rule that allows packets with an "ESTABLISHED" state only matches
packets for which the connection is in netfilter's conntrack table.
The connection is removed from the table after the 5 days of idle.
It is only added again if netfilter accepts a packet for that connection.
So the packet from the client will cause it to be added.

> If that's the case, it seems like a simple fix would be to enable TCP
> keepalive in my app, that would keep netfilter from timing out, right?
> That seems better than extending the netfilter timeout.

Yes that would work.

> How do people normally handle this?

Change the timeout or use keepalives.  I can't think of any other way.
The 5 days is a compromise between keeping valid connections and
timing out dead connections.  There will always be connections for
which it times out too fast or too slow.  I don't think there are
any drawbacks to increasing the timeout if you aren't a router,
but as long as there is a timeout, you need keepalives to be sure.

-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ