This article provides a quick overview of the DNS records required for an email server and presents a minimal sample configuration. The example assumes that you are running servers for both email and the web. Comments indicating the changes if you are using a third party provider are provided. Continue reading
One nagging issue I had with IPv6 was how to distribute DNS server addresses and search lists to my clients. It took a little research to find the solution. On IPv4 I had been using DHCP to do this, but DHCP didn’t seem to be right approach for IPv6.
radvd can be used to distribute both types of data. The following article covers setup on Ubuntu and OpenWRT. The Ubuntu (Debian) examples below should work with any distribution using
/etc//radvd.conf to configure
radvd. Continue reading
SPF (Server Policy Framework) is a simple means to limit the ability of others to forge your identity in email. I first implemented it after a forged identity under my domain was used to send Spam. Once SPF was configured, the bounce messages quickly dropped off.
Although not as frequently implemented as sender address checks, SPF can be used to prevent forgery of the
HELO identity. My mail server uses SPF to check the Identity of the server. This is easier to configure and more reliable than checking the domain in the Mail from address. Even though I treat Neutral and Softfail policies as a Fail policy, I have not detected any false negatives. I verify both the address returned by the
PTR record for the host and the address in the
HELO command. This is primarily because the
PTR record is more likely to have a valid domain. Continue reading
We are quickly running out of IPv4 addresses. Are you ready for World IPv6 Day on June 8th, 2011? I have prepared my configuration on OpenWRT and Ubuntu. This includes configuring DNS using bind, email using Exim, and a Squid web proxy.
Having verified that I could establish IPv6 connectivity, I chose to improve my connectivity. This started with getting a tunnel from Hurricane Electric and updating my configuration. I then updated my bind server and Exim mail server support IPv6 addresses. This posting updates and continues from my post on Implementing IPv6 6to4 on OpenWRT. Review it for information on creating a tunnel and running radvd on OpenWRT. Continue reading
Squid is a proxy service for HTTP and other requests. This article covers installing it and configuring it to run on Ubuntu as a transparent proxy. This documentation includes configuring Web Proxy Auto-Discovery (
I run a heterogeneous configuration. This provided a number of challenges as various implementations of
WPAD were encountered. These each seem to require something different. The final configuration works for Ubuntu, Windows X/P, and Windows Vista. Both Internet Explorer and Firefox configured correctly. Continue reading
I administer an email server for a couple of domains and a few users. Incorrectly configured email servers result in a lot of my administration work. Due to improper configuration, far too many servers look like Spam servers. A little effort in setting up your server can make my life easier, and increase your chance of successfully delivering email everywhere. This article describes steps you should take. Continue reading
Now I have replaced my old firewall with OpenWRT, I needed to enhance the configuration of
dnsmasq to support the network. The old Ubunutu based firewall was already running
dnsmasq, as does the DNS server on the LAN.
I run a mixed network with wired and wireless clients on separate address ranges. DHCP services are provided by the OpenWRT router. An Ubuntu server is the primary DNS server for the wired network. Continue reading