The best ping story I've ever heard(askapache.com) |
The best ping story I've ever heard(askapache.com) |
It was 2002 (2003?), and we had just launched Zipcar in New York. Being a naive start-up we had perhaps not the most stringent security measures in place to prevent fraud and theft. Sure enough, a couple of weeks in and one of our cars went missing. Calls to the member went unreturned, and it became clear that the member was not who they claimed to be and had no intention of returning the car.
At the time Zipcar was using the mobile analog CDPD network for vehicle communications, which had a top speed of something like 19.2k/s and cost us around $1/month per KB of data. However, it also had a limited number of data channels, and since it used the old AMPS network broadcast in the 800 - 900 MHz range. I happened to have an amateur radio license and a radio that was able to receive in that band.
Since we were still in contact with the missing car we knew it hadn't been chopped (yet) and I figured we might be able to use some sort of radio direction finding technique to locate the car. My friend and fellow engineer Carl was able to reprogram the firmware of our embedded electronics to tell us which cell tower the car was in contact with, and with that we could look up the FCC id in their database to find the tower's street address.
So my boss Roy and I hopped into his car and drove to Long Island. We drove up to the tower, and I leaned out the window of his minivan with a yagi antenna and my radio (set to scan the 40 or so CDPD channels.) We asked Carl (back in Boston) to start pinging the car. To the radio this sounded like a half-second burst of static, but since it was very regular it was also very easy to identify. Sure enough, after driving around for a few minutes we picked up the signal. pffft pffft pffft
We drove around the tower in a wide circle until the signal was the strongest, got out to scan the area, then used the new bearing to reduce the circle. Eventually we ended up in the parking lot of the Long Island railroad. There in the back corner was our car, luckily unscathed and none the worse for wear.
Ping rocks.
Spectacular.
Surely most people reading this will know the quote linked without having to even click it.
If I were more sophisticated, I could have measured Wi-Fi RSSIs from it, or tried to bring Bluetooth devices into range. Lots of ways to try to find things nowadays, but none perfect!
It doesn't correctly credit the real author of ping: http://en.wikipedia.org/wiki/Mike_Muuss
Interesting note I hadn't read before: "This Web server was one of the first 50 Web servers on the InterNet, making it a pioneer in its own right."
ping 127.0.0.1 | sed -e 's/.*/ping/' | xargs -d'\n' -n1 sayAnd `sed -e <command>` is redundant, `-e` is used to specify multiple commands.
You'll also need sed -l to limit buffering.
ping <host> | sed -l 's/.*/ping/' | xargs -n1 say cat input |while read a; do do_something_with $a; doneI got into a strange situation where I needed my Mac Mini for something, but it was still trying to connect to an old wired connection instead of the new wireless one. I didn't have any of my cables or display adapters -- just a keyboard.
Long story short: the Mac Mini has an internal speaker, and OS X comes with a vocoder shell program. I managed to boot into the OS and launch terminal, and blindly typed commands into it, piping the output to the vocoder app until I got things working.
> Bing is a point-to-point bandwidth measurement tool (hence the 'b'), based on ping. Bing determines the real (raw, as opposed to available or average) throughput on a link by measuring ICMP echo requests roundtrip times for different packet sizes for each end of the link.
Result: if your machine isn't in one of those blessed ranges, you never get a response to a ping to an outside address. Most users don't complain, because they don't even know what a ping is.
So, it's not just your company, but it's not general practice everywhere.
If you're really worried about user tunneling out through various tricks, you'd probably have to block the whole internet and apply a whitelist of trusted destination hosts.
As a heavy ping user, this blockage always bothered me, so I started working on a similar tool to get around this:
Made it look like there was 50% packet loss on an otherwise perfectly good Cat 5 cable...
(edit: ICMP instead of IP)
The only options in POSIX sed are -e, -f and -n (and -e is usually cargo-culted by people who want -E. -E being a BSD extension enabling extended regular expressions — -r in GNU sed)