In Linux, you can transfer files over the network using netcat. Example article: https://tutorials.technology/tutorials/How-to-transfer-files-over-the-network-using-Netcat.html Snippets from the article: Receiving side ``` nc -l -p 9999 > received_file.txt ``` Sending side ``` nc 192.168.0.1 9999 < received_file.txt ``` In OpenBSD however, I can send the file and receive it in Linux, but upon issuing the example command for receiving in OpenBSD, `nc` returns `usage` message. The [man](http://man.openbsd.org/nc) says that `-l` & `-p` cannot be used together. Questions: - Is it possible to receive files via OpenBSD's netcat? How? - `nc` doesn't exit and doesn't print any mesasage on successful transfer of your file but keeps running. Is there a way to add some human-friendliness in this regard? - Any alternative utilities/approaches that directly and easily transfer files over the network (and exit upon completion)?

@"uxer"#p10126 Try: ```sh nc -N -l 9999 > recv.txt ``` and ```sh nc -N localhost 9999 < file.txt ```

@"rvp"#p10133 My `nc` from `Linux` doesn't know `-N`, yet it knows `-q` that specifies number of seconds between EOF and quit, so `-q 0` is like `-N`. And `-N` or `-q` is needed on sending side only. --- from `OpenBSD` to `Linux`: receiving `Linux` side: ``` nc -l -p 12345 > receiving.file ``` sending `OpenBSD` side: ``` nc -N 192.168.xxx.xxx 12345 receiving.file ``` sending `Linux` side: ``` nc -q 0 192.168.xxx.xxx 12345 receiving.file ``` sending side: ``` nc -N localhost 12345 < sending.file ``` --- I admit that the answer is in the `nc` [manpage](https://man.openbsd.org/nc#DATA_TRANSFER). I had looked at the beginning with mind-boggling list of options, then `EXAMPLES` at the end without my use-case and thus had overlooked the middle part where my exact use-case has been explained. :|

How do I receive files via netcat?

uxer

In Linux, you can transfer files over the network using netcat.
Example article:
https://tutorials.technology/tutorials/How-to-transfer-files-over-the-network-using-Netcat.html
Snippets from the article:

Receiving side

nc -l -p 9999 > received_file.txt

Sending side

nc 192.168.0.1 9999 < received_file.txt

In OpenBSD however, I can send the file and receive it in Linux, but upon issuing the example command for receiving in OpenBSD, nc returns usage message. The man says that -l & -p cannot be used together.

Questions:

Is it possible to receive files via OpenBSD's netcat? How?
nc doesn't exit and doesn't print any mesasage on successful transfer of your file but keeps running. Is there a way to add some human-friendliness in this regard?
Any alternative utilities/approaches that directly and easily transfer files over the network (and exit upon completion)?

rvp

uxer Try:

nc -N -l 9999 > recv.txt

and

nc -N localhost 9999 < file.txt

uxer

uxer alternative utilities/approaches that directly and easily transfer files over the network

Human-friendly cross-platform transfer, sync and even backup tool:
pkg_add syncthing qsyncthingtray
https://openports.se/net/syncthing
https://openports.se/net/qsyncthingtray
https://syncthing.net/

or like nc but more powerful: pkg_add socat
https://openports.se/net/socat
http://www.dest-unreach.org/socat/

https://serverfault.com/questions/246347/whats-the-difference-between-socat-and-netcat
https://scribe.rip/@paxprajapati/preferring-socat-over-netcat-785fc590a050

or
https://www.zerotier.com/
Not ported however, need to compile manually:
https://github.com/zerotier/ZeroTierOne#build-and-platform-notes

or https://justbeamit.com/ or http://0x0.st/

uxer

rvp My nc from Linux doesn't know -N, yet it knows -q that specifies number of seconds between EOF and quit, so -q 0 is like -N.
And -N or -q is needed on sending side only.

from OpenBSD to Linux:
receiving Linux side:

nc -l -p 12345 > receiving.file

sending OpenBSD side:

nc -N 192.168.xxx.xxx 12345 < sending.file

from Linux to OpenBSD:
receiving OpenBSD side:

nc -l 12345 > receiving.file

sending Linux side:

nc -q 0 192.168.xxx.xxx 12345 < sending.file

from OpenBSD to OpenBSD:
receiving side:

nc -l 12345 > receiving.file

sending side:

nc -N localhost 12345 < sending.file

I admit that the answer is in the nc manpage. I had looked at the beginning with mind-boggling list of options, then EXAMPLES at the end without my use-case and thus had overlooked the middle part where my exact use-case has been explained. 😐

uxer

Here are more examples of transferring files via netcat (that I've added as aliases/abbreviations to my shell):

nc_openbsd_receive_vanilla  nc -l 54321 > _filename_
nc_openbsd_receive_notar    nc -l 54321 | gzip -dc | pv > _filename_
nc_openbsd_receive          nc -l 54321 | gzip -dc | pv | tar xvf - -C _path_
nc_linux_receive_vanilla    nc -l -p 54321 > _filename_
nc_linux_receive_notar      nc -l -p 54321 | gzip -dc | pv > _filename_
nc_linux_receive            nc -l -p 54321 | gzip -dc | pv | tar cvf - -C _path_
nc_openbsd_send_vanilla     nc -N -w 1 192.168.88.241 54321 < _filename_
nc_openbsd_send_notar       pv -- _filename_ | gzip -c | nc -N -w 1 192.168.88.241 54321
nc_openbsd_send             tar cvf - _file_or_dir_1_ _file_or_dir_2_ | pv | gzip -c | nc -N -w 1 192.168.88.241 54321
nc_linux_send_vanilla       nc -q 0 -w 1 192.168.88.240 54321 < _filename_
nc_linux_send_notar         pv -- _filename_ | gzip -c | nc -q 0 -w 1 192.168.88.240 54321
nc_linux_send               tar cvf - _file_or_dir_1_ _file_or_dir_2_ | pv | gzip -c | nc -q 0 -w 1 192.168.88.240 54321

Vanilla netcat transfers file(s) but not filename(s), so you have to type filename(s) manually. This can be remedied by a tarball which will carry filenames along with files.

Compressing may or may not be beneficial for your setup. With fast network you may lose time compressing-decompressing. With slow network and fast CPU you may gain.
Of gzip, bzip2 & xz:
gzip is the fastest with worst compression,
xz gives best compression being the slowest,
bzip2 is in between.
-c & -dc options work the same for all 3.
gzip -c/bzip2 -c/xz -c to standard output
gzip -d/bzip2 -d/xz -d decompress

pv visualizes progress
pv -- disambiguates in case your filename starts with a dash

tar c create
tar x extract
tar v verbose
tar f - standard input or output
tar -C extract to directory
(tar doesn't work with -- as it correctly handles filenames starting with a dash and if you type --, tar will try to work on a file named --)

nc -l listen
nc -p (Linux nc) port
nc -N (OpenBSD nc) close connection upon EOF
nc -q 0 (Linux nc) close connection upon EOF
nc -w 1 1 second timeout for establishing connection

rvp

uxer Vanilla netcat transfers file(s) but not filename(s), so you have to type filename(s) manually.

There is a hacky way for that:

nc-send.sh

#!/bin/sh
set -eu
echo "${1##*/}___" | nc -N localhost 9000
exec nc -N localhost 9000 < "$1"

nc-recv.sh

#!/bin/sh
set -eu
FN=$(nc -l 9000)
exec nc -l 9000 > "${FN%___}"