Aaron Adams’s Blowhard Blog

Not long ago, Apple released something it named Broadband Tuner 1.0, and when they say broadband, they mean broadband, as in, multi-hundred megabit fiber connections right to the home. If you’re like me, you have a cable connection, or perhaps a DSL connection, that tops out in the single-digit megabit range. Apple’s Broadband Tuner hurts more than it helps in our case, however, there are some settings that can be tweaked to make things more efficient.

These settings worked very well for me personally. They may do nothing for you, so no promises. I noticed the greatest difference when browsing local fileservers over Airport wireless, and a lesser difference, but still a noticeable one, when surfing the web. As with many of my hints, this requires use of the Terminal, but it’s not hard. So, from an administrator account, start up that Terminal app and type the following at the prompt:

sudo nano /etc/sysctl.conf

… and enter your password. We’re doing exactly the same thing Apple’s Broadband Tuner installer package does - creating and/or editing the /etc/sysctl.conf file. Placing our settings in this file makes them stick across reboots.

Next, copy and paste (or re-type) the following lines into the text editor we opened with the last command:

net.inet.tcp.newreno=1
net.inet.tcp.mssdflt=1440
net.inet.tcp.sendspace=65536
net.inet.tcp.recvspace=65536
kern.ipc.maxsockbuf=524288
net.inet.udp.recvspace=65536
net.inet.udp.maxdgram=65536
net.local.stream.recvspace=65536
net.local.stream.sendspace=65536

Press control-x to save and exit (answer yes when it asks if you want to save). Reboot your machine, and enjoy your network’s new snappiness.

But… Maybe you’d like to try these settings before they become permanent. That’s reasonable. Here’s what you do: At a terminal prompt, add sudo sysctl -w before each of the lines above, like this:

sudo sysctl -w kern.ipc.somaxconn=512

… again, entering the administrator password after the first sudo. The changes are applied immediately, and if you don’t like them, a simple reboot will set everything back to the defaults.