Create a list of supported netcat implementations

[solusipse]

In the past, we've received some reports of issues that were caused by using netcat implementations incompatible with fiche (e.g. #14, #45). It would be nice to give users a list of those that are recommended.

Please feel free to add your recommendations in the comments.

Supported netcat implementations

• https://nmap.org/ncat/

[dashezup]

I tried to test some netcat implementation on my server and nc on macOS, here is the result. (may does not make much sense to compare accurate result, but check which cost less than 1 second and which cost more than 5 seconds is enough)

nc (GNU) 5.342
openbsd-nc 5.324
openbsd-nc -N 0.232
ncat 0.267
libressl-nc 5.234
libressl-nc -N 0.219
nc (macOS) 0.893

I just create alias and run it

$ alias tb="uname | nc termbin.com 9999"
$ time tb

slow as for reach the timeout to finish, since the default timeout is 5 seconds which set on server, it cost more than 5 seconds to finish. fast as for expected speed usually finish in 1 second.

As someone mentioned that in 2015 the GNU netcat seems send the end of stream by default, it was fast at that time. I guess it was changed since then, GNU netcat does not similar option of BSD version's -N, that's why it's slow.

implementation	slow	fast
nc (GNU netcat) (0.7.1)	default
libressl-netcat (3.1.4)	default	-N
openbsd-netcat (1.217)	default	-N
ncat (nmap) (7.91)	--no-shutdown	default
nc on macOS		default

both of this pure bash/zsh way are slow, I didn't figure out a way to solve this.

# bash
alias tb="(exec 3<>/dev/tcp/termbin.com/9999; cat >&3; cat <&3; exec 3<&-)"
# zsh
tb() { zmodload zsh/net/tcp; ztcp ezup.dev 9999; cat >&$REPLY; cat <&$REPLY; ztcp -c $REPLY }

[jsarenik]

busybox nc