Hi *, Tom Fox schrieb:
I¹d take a look at this URL:
1. Enforce reverse DNS lookups on the connecting IP address.
And Block almost any road warrior using dialup.
2. RBL subscriptions, for what those are worth.
Oh, Block the Rest ;-)
Another option (not necessarily recommended) is to force the "from" domain to match the reverse lookup completed on the connecting IP address. This will break many email attempts from legitimate sources because the SMTP servers don't necessarily belong to the sending domain (MX gateway services, for instances).
Right.
-----Original Message----- From: Eric Kahklen [mailto:eric@kahklen.com] Sent: Wednesday, July 21, 2004 11:08 AM To: suse-security@suse.com Subject: [suse-security] Email Spoofing
We are using Suse 9.0 Professional. I am getting email that is claiming to be from my domain and the Posfix logs confirm it is from an outside IP.
Oh, why don`t you just block incomming SMTP Traffic if the from: claims to be inside. This is easy to configure. Use ssl encrypted and accounted SMTP for allowed users. (Road-Warriors) You just need two IP, or two Ports and two instances of postfix. And you are RFC conform. Greetings Dirk TRIA IT-consulting GmbH Joseph-Wild-Straße 20 81829 München Germany Tel: +49 (89) 92907-0 Fax: +49 (89) 92907-100 http://www.tria.de -------------------------------------------------------- working hard | for your success -------------------------------------------------------- Registergericht München HRB 113466 USt.-IdNr. DE 180017238 Steuer-Nr. 802/40600 Geschäftsführer: Hubertus Wagenhäuser -------------------------------------------------------- Nachricht von: dirk.schreiner@tria.de Nachricht an: tom@tremor.com, suse-security@suse.com # Dateianhänge: 0 Die Mitteilung dieser E-Mail ist vertraulich und nur für den oben genannten Empfänger bestimmt. Wenn Sie nicht der vorgesehene Empfänger dieser E-Mail oder mit der Aushändigung an ihn betraut sind, weisen wir darauf hin, daß jede Form der Kenntnisnahme, Veröffentlichung, Vervielfältigung sowie Weitergabe des Inhalts untersagt ist. Wir bitten Sie uns in diesem Fall umgehend zu unterrichten. Vielen Dank The information contained in this E-Mail is privileged and confidental intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient or competent to deliver it to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this E-Mail is strictly prohibited. If you have received this E-Mail in error, please notify us immediately. Thank you