Re: [gentoo-user] ssh-agent

[Jorge Almeida]

On Mon, 20 Nov 2006, Mick wrote:

> On Monday 20 November 2006 17:20, Jorge Almeida wrote:
>> I've been reading the ssh-agent documentation (and googling) and it
>> seems clear, except for two issues for which I couldn't find any docs:
>>
>> What (where) is the ssh-agent cache? Some directory where the decrypted
>> keys are kept? (I mean, if I keep ssh-agent running all day, is it more
>> secure than just having my private keys unencrypted?)
>
> I understand (but could well be wrong) that the ssh-agent creates a new
> directory in /tmp/ with restrictive permissions (0700) and then creates a
> unix socket in it, with rather restrictive permissions (0600). Anyone who can
> connect to this socket (a hacker?!) could access your decrypted keys.  Also,
> root can access the socket and therefore your keys.
>
Well, assuming that you're right, the whole concept is rather
disappointing. After all, the private keys have the same restrictive
permissions, and if the keys are kept in the clear when the agent is
active, then a hacker might fetch the keys from the temporary dir as
well as from ~/.ssh (I'm not really taking into account the extra
security-by-obscurity provided by the variable path to the socket.)

Maybe I didn't understand the whole thing.
>> When adding keys with ssh-add, does it use protected memory to get the
>> passphrases?
>
> I believe the above answer covers this too.  If you run the ssh-add with
> the -c option the agent will run the ssh-askpass when anyone tries to
> retrieve the passwords.
>
What I meant is whether the passphrase to unencrypt a key (in order to
put ot in the cache) is really safe. 
> This is how it used to be last time I looked at it, not sure how it has
> evolved over the last few months.
>
Thanks.

-- 
Jorge Almeida
-- 
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