[scponly] scponly .ssh directory?

[Ralf Durkee]

If the ssh server config (sshd_config) has the directive 
PermitUserEnvironment set to "no" (which is the default on the recent 
OpenSSH releases) then it should not read a ~/.ssh/environment file even if 
it exists. you should still try this and verify it on your system.

Of course there are other files which can be placed in the .ssh such as the 
authorized keys file, which would only allow a user to setup a public key 
for access rather than using a password. This may not be an issue for most 
your usage, but if it is it can be controlled with the directives 
AuthorizedKeysFile for protocol 2.  Protocol 1 should be disabled via the 
"Protocol 2" directive.

Finally the ~/.shosts and ~/.rhosts are also ignored by default, but should 
also not be allowed via "IgnoreRhosts yes".


In short, yes, you can be relatively safe with a writeable home or a 
writeable .ssh directory. but assuming that you are talking about users 
without shell access, then why not eliminate even the minor risk  by not 
allowing them to own their home directories or restricting the write access 
to an incoming directory?  I'm curious if there is some situations where 
this model doesn't fit.

-- Ralf Durkee, GSEC, GCIH
Information Security Consultant
585-624-9551
http://rd1.net


>Date: Wed, 07 Jan 2004 09:58:13 +0100
>From: Joris <joris at linux.be>
>To: scponly at lists.ccs.neu.edu
>Subject: [scponly] scponly .ssh directory?
>
>Hi,
>
>Is it still necessary to restrict user-access to the .ssh directory in
>the filesystem?
>This is the only showtopper for me to integrate scponly in my system.
>
>Rssh (rssh.sf.net) seems not to require .ssh restrictions? But it lacks
>application/client support... (it's the unison support in scponly I'm
>looking forward to ;))
>
>--
>    Greetings
>     Joris
>     joris at linux.be
>------------------------------