ssh-keygen does not respect the syntax for hostname with -F option

[Daniele Palumbo]

Hi all,

I've filed some weeks ago a bug, related to ssh-keygen.
As i see no reply in bugzilla, maybe is better to write also here :)

https://bugzilla.mindrot.org/show_bug.cgi?id=3284

I've tested the bug in gentoo (openssh v8.4p1) and osx big sur (openssh v8.1p1), still seems that i can't select more than one option in the Version list.

OSX:
$ ssh -V
OpenSSH_8.1p1, LibreSSL 2.7.3
$
Gentoo:
$ ssh -V
OpenSSH_8.4p1, OpenSSL 1.1.1g  21 Apr 2020
$

From the man page of ssh-keygen:
     -F hostname | [hostname]:port

I have hosts with ssh running on a different port, 
but for the sake of bug reproducer, let's remain on port 22.

I assume that the syntax is:
$ ssh-keygen -F 172.16.66.8:22

But, with the given syntax, port 22 and any other port fail

Example:
$ ssh-keygen -F 172.16.66.8:22 -v
$ echo $?
1

FWIW:
$ ssh-keygen -F [172.16.66.8]:22 -v
$ echo $?
1
$


Everything is working without any port specified:
$ ssh-keygen -F 172.16.66.8 -v
# Host 172.16.66.8 found: line 44
172.16.66.8 ecdsa-sha2-nistp256 [...]
$ echo $?
0

HTH,