From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Svein E. Seldal" Subject: Re: Connection opening problem (prev: FTP/auth problems (slooow links)) Date: Tue, 15 Oct 2002 23:21:17 +0200 Sender: netfilter-admin@lists.netfilter.org Message-ID: <3DAC86CD.9030506@solidas.com> References: <3DA97045.2040803@solidas.com> <20021013235022.ZXXG27697.mta05-svc.ntlworld.com@there> <3DAA80EA.7070106@solidas.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Errors-To: netfilter-admin@lists.netfilter.org List-Help: List-Post: List-Subscribe: , List-Id: List-Unsubscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii"; format="flowed" Cc: netfilter@lists.netfilter.org Hello, The root of my problem was this: > [0:0] -A SYNFLOOD -m limit --limit 1/s --limit-burst 4 -j RETURN > [0:0] -A SYNFLOOD -j DROP > [0:0] -A CHECK -p tcp -m tcp --tcp-flags SYN,RST,ACK SYN -j SYNFLOOD When the HTTP/FTP-clients etc. spawned several connections (in this case >4) to download files, the router blocked them. I guess that it adds protection to keep the SYNFLOOD check there. What are sensible values to use on -m limit, making it work for flooding, yet not stopping normal clients? Thanks guys, Svein