From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Simon A. Boggis" Subject: Re: TCP delay, SMTP errors Date: 11 Jun 2002 11:41:03 +0100 Sender: netfilter-admin@lists.samba.org Message-ID: <1023792070.960.7.camel@hal9000> References: <001601c210bf$d1a5fef0$2901a8c0@amos> <3D052994.CD0F1237@planetconnect.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-BmLH/jtJHzO2SRJqWrTw" Return-path: In-Reply-To: <3D052994.CD0F1237@planetconnect.com> Errors-To: netfilter-admin@lists.samba.org List-Help: List-Post: List-Subscribe: , List-Id: List-Unsubscribe: , List-Archive: To: netfilter@lists.samba.org --=-BmLH/jtJHzO2SRJqWrTw Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Mon, 2002-06-10 at 23:35, Doug Monroe wrote: > Nathan Cassano wrote: > > Our website (on an internal NAT'ed network) connects our email > > server (on an external network). The website uses a SMTP PHP class to > > send mail using socket connections. The problem is a delay in connectin= g > > to the mail server that causes the class to quit prematurely. I fixed > > what happens when you use telnet from the website box to the mail server'= s > port 25? do you get a delay rec'ving the SMTP banner? Likely has nothing = to do > with netfilter...my money's on a paranoid SMTP trying to do a reverse DNS > lookup (or identd?) causing the delay. Maybe there's no PTR record for th= e NAT > (public) IP of the website? Maybe your SMTP server has a big-ish list of = DNS > hosts to try before it finally timesout? My first suspicion would be a timing out ident from the mail server. I always send rejects on port 113/tcp (ident) for this reason. Some MTAs absolutely insist on doing an ident (or timing out trying) before they accept your mail. It could be useful to tcpdump at your firewall/router, or on the machine doing the smtp connection (if no border filtering) and see what is going on. Simon --=20 ---------------------------------------------------------------------- Dr Simon A. Boggis Systems Programmer Department of Computer Science, Tel. 020 7882 7522 Queen Mary, University of London, London E1 4NS UK.=20 ---- GPG public key ---- --=-BmLH/jtJHzO2SRJqWrTw Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQA9BdO/C8auviztJ4cRAhYGAJwMzDKkpPzeyM7h6FySn68qYSoOtACaA/XN YtdL0maSAHrO2ohJf0JiGoA= =ADIi -----END PGP SIGNATURE----- --=-BmLH/jtJHzO2SRJqWrTw--