[CentOS] Q: respecting .ssh/id_rsa

Fri May 8 17:23:57 UTC 2015
m.roth at 5-cent.us <m.roth at 5-cent.us>

Devin Reade wrote:
> --On Friday, May 08, 2015 09:58:32 AM -0400 "James B. Byrne"
> <byrnejb at harte-lyne.ca> wrote:
>
>> While attempting to debug something else I ran across this:
>>
>> ssh -vvv somehost
>> . . .
>> debug1: Connection established.
>> debug1: permanently_set_uid: 0/0
>> debug1: identity file /root/.ssh/identity type -1
>> debug1: identity file /root/.ssh/identity-cert type -1
>> debug3: Not a RSA1 key file /root/.ssh/id_rsa.
>> debug2: key_type_from_name: unknown key type '-----BEGIN'
>> debug3: key_read: missing keytype
>> debug3: key_read: missing whitespace
>>
>> [snip]
>>
>> The password-less connections complete in any case but I am perplexed
>> as to what is the problem with the root identity key that ssh is
>> reporting.
>>
>> Can anyone explain to me what this means?
>
> IIRC there was a time when id_rsa could refer to either an
> RSA1 key or RSA2 key.  I believe ssh is first trying to read
> the file as an RSA1 key, finding problems, and then opening it
> as an RSA2 key.  In fact, if you scroll down from there you probably
> see a line like the following:
>
>    debug1: identity file /home/somebody/.ssh/id_rsa type 1
>
> which is a successful read (note the type is 1 and not -1).
>
> In other words, it's nothing to worry about.  The messages are
> a bit different under CentOS 7 (I suspect you're running CentOS 6
> on the client), but they say about the same thing.
<snip>
I would *strongly* recommend editing your /etc/ssh/sshd_config, and
comment or delete the fallback, and replace it, like:
#Protocol 2,1
Protocol 2

That way, it won't even try.

       mark