Author Archives: Dan Siemon

Sagrada Família

I was recently in Barcelona and took the opportunity to see Sagrada Família.

Wow, I’ve been in a lot of churches but this one completely blew me away. It feels like a building from a Sci-Fi movie. Construction started in 1882 and isn’t expected to be complete until 2026.

IPv6 deployment day is here

A few minutes ago major Internet companies enabled IPv6 permanently. Happy IPv6 day!

World IPv6 Day

World IPv6 Launch

The view from my server:

[dan@alpha ~]$ ping6 -n -c 1 www.google.com; ping6 -n -c 1 www.yahoo.com; ping6 -n -c 1 www.facebook.com
PING www.google.com(2001:4860:4008:802::1012) 56 data bytes
64 bytes from 2001:4860:4008:802::1012: icmp_seq=1 ttl=59 time=5.04 ms

--- www.google.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 5.048/5.048/5.048/0.000 ms
PING www.yahoo.com(2001:4998:f00d:1fe::3001) 56 data bytes
64 bytes from 2001:4998:f00d:1fe::3001: icmp_seq=1 ttl=60 time=31.6 ms

--- www.yahoo.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 31.638/31.638/31.638/0.000 ms
PING www.facebook.com(2a03:2880:10:1f02:face:b00c:0:25) 56 data bytes
64 bytes from 2a03:2880:10:1f02:face:b00c:0:25: icmp_seq=1 ttl=54 time=87.7 ms

--- www.facebook.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 87.754/87.754/87.754/0.000 ms

Copying outbound emails

I like to have a copy of the emails I compose in my Inbox because it makes threaded message views complete. In the past I’ve used outbound mail filters but this is a bit annoying to maintain when you use several mail clients. A couple weeks ago I finally got around to configuring a server side solution.

The solution I settled on uses MIMEDefang running as a Sendmail milter with a simple rule to add a recipient. I found part of this solution online but I didn’t find a complete example so hopefully this is useful to someone.

Since I don’t need MIMEDefang for anything else I removed all the filter functions from mimedefang-filter and added the following function:

sub filter_end {
        if ($Sender =~ /example\.com>$/ || (grep { /example\.com>$/ } @Recipients)) {
                add_recipient('dan@example.com');
        }
}

Don’t forget to add “1;” to the end of the file if you don’t have any other rules defined (see the sample file).

Codel AQM

Nichols and Jacobson have recently released a paper on ACM Queue which outlines their new AQM called Codel. At a very high level Codel can be thought of as a self tuning RED. This is a very interesting development and I look forward to testing it on my Internet connection. The paper is worth reading just for some of the insights into network behavior.

Also, Jonathan Morton provides a good summary of what’s novel about Codel on the Bufferbloat list.