netdev - Re: DSCP values in TCP handshake

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]

Message-ID: <20110418211637.57f1cfb8@nehalam>
Date:	Mon, 18 Apr 2011 21:16:37 -0700
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Mikael Abrahamsson <swmike@....pp.se>
Cc:	Joe Buehler <aspam@....net>, Eric Dumazet <eric.dumazet@...il.com>,
	netdev@...r.kernel.org
Subject: Re: DSCP values in TCP handshake

On Tue, 19 Apr 2011 05:50:34 +0200 (CEST)
Mikael Abrahamsson <swmike@....pp.se> wrote:

> On Mon, 18 Apr 2011, Stephen Hemminger wrote:
> 
> > If the DSCP bits are reflected, then it could allow for even better SYN 
> > flood attack. Attacker could maliciously set DSCP to elevate priority 
> > processing of his bogus SYN packets and also cause SYN-ACK on reverse 
> > path to also take priority.
> 
> Incoming, it's already too late. Outgoing, yes, that might be a problem, 
> but if you have a QoS enabled network then you might as well solve that in 
> the network, not in the host.
> 
> Does Linux internally look at DSCP when deciding what SYNs to handle 
> first? If not, I think the above reasoning is misdirected.

Linux does not look at DSCP of incoming packets (there is no queue).

Of course, you can do anything with qdisc, and iptables.
--
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