Domain name suffix woes

[Nico Kadel-Garcia]

On Thu, Mar 2, 2017 at 7:09 AM, Darren Tucker <dtucker at zip.com.au> wrote:
> On Thu, Mar 2, 2017 at 10:46 PM, Martin Rys <spleefer90 at gmail.com> wrote:
> [...]
>> `ssh user at 330` - That gets me an error:
>> ssh: connect to host 330 port 22: Invalid argument
>>
>> I'm assuming that when the hostname is pure number, it ignores domain
>> suffix. As just a number cannot be an actual IP, could this behavior be
>> fixed in OpenSSH?
>
> not really, the behaviour in question is in they system libraries,
> which think it's an IP address (single numeric, number.number and
> octal are all valid but uncommon representations of IP addresses).
>
> $ gethostip localhost
> localhost.localdomain 127.0.0.1 7F000001
>
> $ gethostip 330
> 330 0.0.1.74 0000014A
>
> $ telnet 330
> Trying 0.0.1.74...
> telnet: connect to address 0.0.1.74: Invalid argument
>
> You can work around it with an entry in ~/.ssh/config:
>
> Host 300
>    Hostname 330.blah.domain.com

Note that SSH is hardly the only tool vulnerable to t his problem.
This is why most of us never use raw numbers as shortened hostnames,
even if it is convenient on occasion.