netselect - choose the fastest server automatically

netselect [-v|-vv|-vvv|-vvvv] [-m HOPS] [-s SERVERS] [-t PACKETS] host ...

netselect determines several facts about all of the hosts given on the command line, much faster than you would if you manually tried to use ping and traceroute.

For each host, netselect figures out the approximate ping time (though not as accurately as ping does), the number of network "hops" to reach the target, and the percentage of ping requests that got through successfully. Then netselect calculates the "score" of each operational host based on these values. A lower score is better, in the end it prints one line showing the server with the best score.

# netselect -vv ftp.fceia.unr.edu.ar ftp.kulnet.kuleuven.ac.be \
		 ftp.cdrom.com ftp.debian.org ftp.de.debian.org

This is the output:

ftp.fceia.unr.edu.ar         2792 ms  23 hops  100% ok ( 1/ 1) [ 9213]
ftp.kulnet.kuleuven.ac.be    9999 ms  30 hops    0% ok
ftp.cdrom.com                  94 ms   8 hops  100% ok (10/10) [  169]
ftp.debian.org                 46 ms  15 hops  100% ok (10/10) [  115]
ftp.de.debian.org            9999 ms  30 hops    0% ok
  115 ftp.debian.org

The value in brackets is the "score" of each operational host based on these values. A lower score is better. The last line shows the server with the best score. If we had not used '-vv' on the command line, only this last line would have been printed.

Note that for ftp.kulnet.kuleuven.ac.be and ftp.de.debian.org in this case, nothing got through at all. That indicates that either the host doesn't exist, or it is down.

-v

Verbose mode. Displays nameserver resolution messages to stderr. You probably want this so that you don't get bored waiting for a hundred name resolutions to finish.

-vv

Very verbose mode. Displays nameserver resolution and statistics (not just scores) to STDERR and STDOUT.

-vvv

Very very verbose mode. Everything -vv prints, plus it print every packet received as it happens. Good for debugging or trying to figure out how it works.

-vvvv

Very very very verbose mode. Everything -vvv prints, plus a trace of all packets sent.

-m HOPS

Maximum TTL (time to live). Don't accept hosts that are further than HOPS away.

-s SERVERS

Print this many "top-scoring" SERVERS at the end of the list. If SERVERS is 0, then this disables printing of high scores.

-t PACKETS

Make sure at least 50% of the hosts get tested with this many PACKETS. The more packets you use, the more accurate are the results... and the longer it takes to run. The default is 10, which is usually okay.

ping(8), traceroute(8), netselect-apt(1).

Avery Pennarun <apenwarr@nit.ca>