[Bug 2310] functionality to start process before ssh and/or to "wrap" such command around ssh

[bugzilla-daemon at mindrot.org]

https://bugzilla.mindrot.org/show_bug.cgi?id=2310

Christoph Anton Mitterer <calestyo at scientia.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|WONTFIX                     |---

--- Comment #3 from Christoph Anton Mitterer <calestyo at scientia.net> ---
Actually I've made some further tests on this issue in the meantime and
it seems as if there is just some "timing issue", which is why I reopen
the issue for now, perhaps you can have a look, whether that could be
fixed easily.



Remember, what I've basically tried to achieve is to get automated
(i.e. passwordless) login to ssh hosts that require a kerberos ticket
(+afs) for login and for the home dir access.
And not only this, the whole thing should also work for multiple reams,
i.e. when I connect to some nodes at CERN I want a ticket for CERN.CH
being automatically generated and used with ssh,... while when I
contact
to the university's nodes, I want the same for the PHYISIK.LMU.DE
realm.


Okay from the k5start side everything seems to work. What I do is
basically
$ k5start -q -f kt -K 10 -- user at REALM ssh ....

The keytab file (kt) works, and when I run ssh with the above, login
works fine as well and the I get an AFS ticket (it's probably created
on the server side).


Now I try to get the whole thing into ssh_config, because I want all be
done automatically and especially for different realms, so I do about
the following:

Host lxplus.cern.ch
        GSSAPITrustDns yes

Host *.cern.ch
        User mitterer
        GSSAPIAuthentication yes
        GSSAPIDelegateCredentials yes
        GSSAPIRenewalForcesRekey yes 
        ProxyCommand k5start -q -f kt -K 10 -- mitterer at CERN.CH nc %h
%p

The usage of ProxyCommand with k5start and nc is a hack here, which I
hoped to solve the problem that the ticket is generated before the
connection is done,... and nc %h %p simply passes everything through.
In other words, this is the trick which I've tried to get the feature
what I've asked for in the original submission of this ticket.


This however doesn't work, which makes sense, as the ssh process has no
way to know where the credential cache is that k5start creates randomly
for this program invocation (nc), e.g. at /tmp/krb5cc_1000_VZ7FI5.

It also exports KRB5CCNAME='FILE:/tmp/krb5cc_1000_CERN', of course, but
this only gets known to nc.

At that point, ssh already looked for KRB5CCNAME, didn't find any, and
never tries again.



Do you see any simple solution to get that working somehow? Maybe even
in a completely different way (extending ssh-agent and k5start to
interact?) or some other tricky hack?
If not, and you still think that adding such feature isn't worth to
make ssh nicely usable with kerberos, than just close it again if you
feel necessary.


Thanks,
Chris.

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