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[14.3.55.68]) by smtp.gmail.com with ESMTPSA id h193sm13425194pfe.30.2020.05.12.21.39.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 May 2020 21:39:13 -0700 (PDT) Date: Wed, 13 May 2020 13:39:08 +0900 From: Benjamin Poirier To: Jan Engelhardt Cc: zenczykowski@gmail.com, maze@google.com, pablo@netfilter.org, fw@strlen.de, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org Subject: Re: [PATCH v2] doc: document danger of applying REJECT to INVALID CTs Message-ID: <20200513043908.GA25216@f3> References: <20200512210038.11447-1-jengelh@inai.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200512210038.11447-1-jengelh@inai.de> Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On 2020-05-12 23:00 +0200, Jan Engelhardt wrote: > Signed-off-by: Jan Engelhardt > --- > > Simplify the trigger case by dropping mentions of P_3. > New -A commands as proposed. > > extensions/libip6t_REJECT.man | 20 ++++++++++++++++++++ > extensions/libipt_REJECT.man | 20 ++++++++++++++++++++ > 2 files changed, 40 insertions(+) > > diff --git a/extensions/libip6t_REJECT.man b/extensions/libip6t_REJECT.man > index 0030a51f..cc845e6f 100644 > --- a/extensions/libip6t_REJECT.man > +++ b/extensions/libip6t_REJECT.man > @@ -30,3 +30,23 @@ TCP RST packet to be sent back. This is mainly useful for blocking > hosts (which won't accept your mail otherwise). > \fBtcp\-reset\fP > can only be used with kernel versions 2.6.14 or later. > +.PP > +\fIWarning:\fP You should not indiscrimnately apply the REJECT target to ^ typo > +packets whose connection state is classified as INVALID; instead, you should > +only DROP these. > +.PP > +Consider a source host transmitting a packet P, with P experiencing so much > +delay along its path that the source host issues a retransmission, P_2, with > +P_2 being succesful in reaching its destination and advancing the connection ^ typo