openssh unix dev - Dec 2020 - ssh_config: Hostname with multiple IP addresses

On 12/11/20 10:28 AM, Brian Candler wrote:
> On 11/12/2020 08:42, Harald Dunkel wrote:
>> ssh_config(5) explicitly allows numeric IP addresses (plural) on the
>> Hostname config line in .ssh/config,
> 
> Can you point to where it says that explicitly? I see in ssh_config(5):
> 
>  ???? HostName
>  ???????????? Specifies the real host name to log into.
> 
It says
      Hostname
              Specifies the real host name to log into.  This can be used to
              specify nicknames or abbreviations for hosts.  *Arguments to
              Hostname* accept the tokens described in the TOKENS section.  Nu-
              meric *IP addresses* are also permitted (both on the command line
              and in Hostname specifications).  The default is the name given
              on the command line.

Of course I understand that this is ambiguous. I don't expect any miracles
here.

Having both IPv4 and IPv6 address defined for a specific Host would be
reasonable, though.


Regards
Harri

>Having both IPv4 and IPv6 address defined for a specific Host would be
How would your client know which one to go to?

Say I had:

Host foo
Hostname 192.168.2.2 192.168.2.3

Do I end up at 192.168.2.2 randomly half the time, and 192.168.2.3 the rest of
the time?

Even if we accept that the wording is ambiguous, it is easily disambiguated by
thinking about the logic involved.

Whereas, if we accept the logic that Hostname can take multiple arguments, then
you might as well have:

Host foo
Hostname *

And thereby try to log into all servers in the world simultaneously O_o