I saw couple of discussion around in this list as well as others
about how to exploit ppolicy with ssh : here are some thought.
Currently, I am in a situation where I have inserted my users
public ssh keys in ldap (openssh-ldappubkey shema) and
instructed sshd to consult ldap for ssh public keys, adding in
I also have authorized password authentication , in ssh_config:
My current policy is the following :
- All my users must have a password in ldap (that is used by
applications other than ssh)
- not all my users may have an ssh key (some never use ssh)
Everything works as I want.
I now want to introduce ppolicy overlay and would like to enforce
rules for password management even for users that mainly use
Practically and basically : when a user with valid ssh key ask for
an ssh connexion, I would like ssh to behave exactly as if this user
had typed a correct "loging/password" and therefore check for
ppolicy situation before granting access.
- if the account is 'ppolicy desactivated', ssh would refuse to
provide the session
- if the password is "ppolicy oudated", then ssh would warn to
change it (and decrease 'pwdGraceAuthnLimit*'*?)
... and so on.
I thought about two options/alternatives to do that :
* try to tune pam (may be there would be a way to tell pam to check
for user ppolicy fields once authentication has been done before
granting access ?)
* add some sort of flag (aka: --ppolicy) to sss_ssh_authorizedkeys
to instruct sss_ssh_authorizedkeys to check for user ppolicy (use
'ldap_default_bind_dn' as a binding user) and if there is an issue
return a "ppolicy error message" rather than the user ssh key ?
These are just some thoughts.
I'm currently exploring the first option (but I'm not a 'pam' expert and
I'm even not sure that the ssh authentication process goes through
pam if a valid key is found, even with 'UsePAM yes').
I would appreciate any guidance, advices or experiences from you
on that particular issue.