RyanSimpkins.com -

Regional SPAM Blocking in Postfix

Ryan Simpkins — Thu, 09 Jul 2009 13:07:50 -0600

There have been a couple of requests for the cidr file I'm using to block spam in postfix. This only works if you know you'll likley never recieve mail from outside the US (or you don't want to). Further, it only works for fairly low traffic mail servers. If you really want to use it for a high traffic site, change the 451s to REJECTs. If you have a lot of users or recieve mail from outside the US often you won't want to use this approach. Use the personal_cidr file to keep a list of your personal blocks, or to OK clients.

This is the real file I use, so it will be updated over time. You could wget it in a cron every 2-3 months for example. If you have any updates to it - please send them along. Also, this list may be out of date. Any corrections/removals would be very welcome.

http://ryansimpkins.com/regional_cidr

In main.cf, add this (I also do these RBLs which really help):

smtpd_client_restrictions =
    cidr:/etc/postfix/personal_cidr,
    cidr:/etc/postfix/regional_cidr,
    reject_rbl_client zen.spamhaus.org,
    reject_rbl_client bl.spamcop.net,
    reject_rbl_client dnsbl.njabl.org

Don't forget to run postmap & restart.

postmap /etc/postfix/personal_cidr
postmap /etc/postfix/regional_cidr
/etc/init.d/postfix restart

Incidently, I had to unblock a server in Euorpe last night. Since I sent 451's back instead of REJECTs, adding the MX to my whitelist was all that I had to do. The mail came through a few minutes later.

New Server

Ryan Simpkins — Wed, 08 Jul 2009 16:13:57 -0600

A new server has been provisioned for ryansimpkins.com. Main upgrades include a better storage array, lower bandwidth costs, and faster gear. Things have been changing rapidly on the backend over the last six months. To keep up with the latest on what I am doing, you might follow me better over at my LinkedIn profile.

Welcome to RyanSimpkins.com

Ryan Simpkins — Sun, 31 Dec 2006 10:37:50 -0700

Welcome to ryansimpkins.com. Ryan Simpkins is a Linux computer expert located in Utah. Ryan has been professionally administrering Linux systems for ten years. If you are currently experiencing a Linux related emergency and need a sys admin NOW - you can call him 24/7/365.

Ryan does not update this main site often. Behind the scenes, however, there are constant changes occuring. Feel free to contact him via e-mail, phone, or IRC chat. He is more than happy to answer any questions at all.

Quick Topic: DNS Root

Ryan Simpkins — Tue, 09 May 2006 19:52:06 -0600

Have you ever performed a 'whois' on a domain name to see what name servers are authoritative for it? Did you know that this information is not the information that is used when your domain name is actually resolved to an IP address? The authoritative name servers for a domain are actually stored in the Internet's DNS root servers. The data you receive from performing a whois on a domain is for convenience only, and may not always be accurate. In this article we will examine the roll of the DNS root servers, and the basics of domain resolution.