NETSELECT(1)
🌸 NETSELECT(1) 🌸
okay bestie, gather round, because netselect(1) is a General Commands Manual page and it is genuinely one of the most useful little gremlins in your toolbox. it picks the fastest server for you, automatically, no cap. let's get into it 💅
🎀 NAME 🎀
netselect — choose the fastest server automatically ✨
🦋 SYNOPSIS 🦋
netselect [-v|-vv|-vvv|-vvvv] [-m HOPS] [-s SERVERS] [-t PACKETS [-I]
[-D] host ...💖 DESCRIPTION 💖
so basically, netselect figures out a whole bunch of facts about every single host you hand it on the command line, and it does it way faster than you would if you sat there manually running ping and traceroute like some kind of medieval peasant. fr fr.
for each host, netselect works out:
- the approximate ping time — though not as accurately as
pingdoes, just so we're clear, it's giving estimates not precision - the number of network "hops" it takes to reach the target
- the percentage of ping requests that actually got through successfully
then it takes all of that and calculates the "score" of each operational host based on these values. and here's the key thing: a lower score is better. in the end it prints one line showing the server with the best score. iconic behavior honestly 👑
if the DNS name has multiple IP addresses associated with it, netselect will test each of the IP addresses independently. in that case, netselect will report the IP address of the fastest server — unless the -D option is used, of course. iykyk.
and one more thing before we move on: if the number of found hosts is not the same as the number you requested (using -s), netselect will emit a warning message. and if no hosts are found at all? the program will also end with an error return value. so, like, pay attention to that. 💀
🌈 EXAMPLES 🌈
here's the vibe in action:
# netselect -vv ftp.fceia.unr.edu.ar ftp.kulnet.kuleuven.ac.be \
ftp.cdrom.com ftp.debian.org ftp.de.debian.organd 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.orgthe value in brackets is the "score" of each operational host, based on these values. lower score = better, always. and that last line? that's the server with the best score, the winner, the main character 🫶
if we had not used -vv on the command line, only this last line would have been printed. so like, -vv is the difference between "one line" and "the whole gossip".
also 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. either way, not it. 😭
next up:
# netselect -vv http.us.debian.orgthis is the output:
204.152.191.39 300 ms 17 hops 90% ok ( 9/10) [ 899]
35.9.37.225 9999 ms 30 hops 0% ok
64.50.233.100 9999 ms 30 hops 0% ok
128.30.2.36 183 ms 15 hops 90% ok ( 9/10) [ 510]
149.20.20.135 226 ms 18 hops 90% ok ( 9/10) [ 702]
510 128.30.2.36in this case, since the single name has multiple DNS addresses, all of the servers will be tested independently and the fastest server will be provided. slay ✨
so if you noticed the above output, you'll see that the time for some hosts is 9999 ms. this is typically an indication of remote hosts blocking the UDP probes netselect relies on. to prevent this issue you can use ICMP tests. for example, repeating the above test using ICMP, that is:
# netselect -I -vv http.us.debian.orgyields the following output:
204.152.191.39 291 ms 17 hops 100% ok (10/10) [ 785]
35.9.37.225 180 ms 19 hops 66% ok ( 2/ 3) [ 783]
64.50.233.100 140 ms 12 hops 100% ok (10/10) [ 308]
128.30.2.36 182 ms 15 hops 100% ok (10/10) [ 455]
149.20.20.135 227 ms 18 hops 100% ok (10/10) [ 635]
308 64.50.233.100in this last example the selected server will change, since — actually — the fastest server is one that also actively blocks UDP probes. plot twist 🍓
you can also use the tag feature, based on postpending the server name with itself, so the result includes both the fastest IP address and the original server name. for example, running a query with tags such as this one:
# netselect -I -vv http.us.debian.org:http.us.debian.orgwill yield output similar to:
35.9.37.225:http.us.debian.org 9999 ms 30 hops 0% ok
64.50.233.100:http.us.debian.org 9999 ms 30 hops 0% ok
64.50.236.52:http.us.debian.org 9999 ms 30 hops 0% ok
128.30.2.36:http.us.debian.org 189 ms 14 hops 90% ok ( 9/10) [ 504]
199.6.12.70:http.us.debian.org 286 ms 17 hops 90% ok ( 9/10) [ 858]
504 128.30.2.36:http.us.debian.orgor you can use the -D option to force netselect to print out only DNS names. for example:
# netselect -I -vv -D ftp.us.debian.org ftp.ru.debian.orgwill yield output similar to:
128.30.2.36 186 ms 14 hops 100% ok (10/10) [ 446]
199.6.12.70 294 ms 17 hops 87% ok ( 7/ 8) [ 907]
35.9.37.225 177 ms 19 hops 66% ok ( 2/ 3) [ 768]
64.50.233.100 141 ms 12 hops 100% ok (10/10) [ 310]
64.50.236.52 162 ms 13 hops 100% ok (10/10) [ 372]
ftp.ru.debian.org 112 ms 18 hops 100% ok (10/10) [ 313]
310 ftp.us.debian.orgas you can see here, netselect will select a DNS name (in the example 'ftp.us.debian.org') which is associated with multiple IP addresses over other servers, as long as there is one server in the pool faster than the others.
however — and this is the important bit, bestie — using the DNS name for a server configuration might lead to actually slower throughput if, on average, the different IP addresses are not as responsive. in the above example, 'ftp.ru.debian.org' is second on the list and might be a better option (again, on average) than 'ftp.us.debian.org'. so like, read the room before you commit. 🙈
👑 OPTIONS 👑
-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. lowkey essential honestly.-vv— Very verbose mode. Displays nameserver resolution and statistics (not just scores) to STDERR and STDOUT.-vvv— Very very verbose mode. Everything-vvprints, 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-vvvprints, plus a trace of all packets sent. maximum yapping, zero secrets 💅-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 is0, 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 is10, which is usually okay.-I— Use ICMP instead of UDP probes. On some occasions (e.g. firewalled hosts) UDP probes like those used in traceroute will get filtered out and hosts might be perceived as dead. Using this option will makenetselectuse ICMP probes instead. the fixer ✨-D—netselectprovides the IP address of the servers that are tested if the name resolves to more than one address (i.e. the remote end is using DNS round-robin). This makes it easier to spot which is the fastest server of a pool but might not be useful if you wish to configure a system daemon with the DNS name or if the remote service does not accept calls to its IP address (as some HTTP servers do). This option forcesnetselectto present the final server list using the original DNS name instead of the IP address if the DNS name resolves to more than one IP address.
🧚 SEE ALSO 🧚
ping(8), traceroute(8), netselect-apt(1).
💜 AUTHOR 💜
Avery Pennarun <apenwarr@gmail.com>
and that's the whole page, bestie 🫶 go forth and let netselect pick your fastest server, you absolute icon 👑
this was the DEBIAN edition of the NETSELECT(1) manual page, dated March 14, 2004 — yes it's vintage, yes it still eats 💅
📦 where this page comes from
- debian bookworm: netselect 0.3.ds1-30.1
- 💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on : a language model's rewrite of the original, under its terms