Server Wake-on-LAN on access

Most ethernet NICs support Wake on LAN feature – when a so-called magic packet wakes up the computer. This can save money, as running a Mac Pro 1,1 server fully awake could cost you at least $24.5 per month of electricity in California prices (that’s at the lowest tier of consumption).

To put my server to sleep, I use powernap (easy install via apt in Ubuntu). As I use ssh to access files, tracking TCP port 22 connection to keep server awake is a no brainer config setting.

There is a number of software utilities that could be used to send a magic packet to wake a remote machine, but if all you want is to access a file, firing up the utility each time seems too much hassle.

Running the command below on a unix-based router (OpenWRT, DD-WRT) connected to the same LAN as server will send a magic packet to your server on any access attempt. It works by sniffing for broadcast ARP packets looking for server’s IP address (e.g. and issues a magic packet to its MAC address (e.g 00:17:f2:0a:a6:3f).

Just edit the address values below, substituting LAN bridge interface, server’s IP address and MAC address, and put this line into the startup script of your router:

tcpdump -i eth1 -l arp and ether[0x26:1]=192 and ether[0x27:1]=168 and ether[0x28:1]=1 and ether[0x29:1]=191|while read -r line; do etherwake -i eth1 00:17:f2:0a:a6:3f; done&

good  luck!

Planning Trips with QMapShack

I like having a plan for my hiking and biking trips (Northern California), to have an idea about their length and aggregated climb, and also to have a track in my GPS to stop wondering if I am taking the right route.

Unfortunately, I could not do that with Garmin software, Basecamp. Proprietary $$$ Topo 24k map doesn’t have bike trails, free Opencycle map doesn’t have elevations.

I found a perfect solution in QMapShack, a free mapping application for Linux, Windows and Mac, which can also use free map and elevation data. This is an attempt on an end-to-end guide from setting it up to using it to plan trips.


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How to fit a bicycle in 4 easy steps



Desired use, weight, quality of components, price – just a few very important attributes for
choosing a bike. None of the above matter if the bike does not fit.

Riding an improperly adjusted bike is painful. If your knees or back are in pain or your seat is killing you, the most likely reason is fit.

How am I an expert? I bought my bike and adjusted it for 6 months, searching the Internet for tips and explanations, until I got it right. I have a mountain bike, so while the tips below may help with road bike, I am sure there is a number of things I simply don’t know. Also, there are other adjustments you could make to improve performance, but these 4 are an absolute must – read on. Continue reading