On 8/2/06, Gary Schlachter <Gary.Schlachter@tavve.com> wrote:
Since I am told OpenSSH works with radius, it should work with TACACS as
well. I believe I have the /etc/pam.d/sshd setup correctly as below:
#%PAM-1.0
auth required pam_stack.so service=tacacs
auth required pam_nologin.so
account sufficient pam_stack.so service=tacacs
password required pam_stack.so service=tacacs
session sufficient pam_stack.so service=tacacs
session required pam_limits.so
session optional pam_console.so
So my TACACS pam is getting called with the incoming user. OpenSSH
complains that the incoming user is not found but continues processing.
My pam authenticates the incoming user and sends back the response to
OpenSSH to prompt for the password. I enter the password. Now the
incoming request to my pam does not have the password that was entered
but the hardcorded value in OpenSSH of "****INCORRECT" which indicates
that sshpam_authctxt->valid is 0. Obviously this fails from the TACACS
server
You want to make sure UsePAM is set to `yes' and you are using
keyboard interactive for protocol 2 and challenge response for
protocol 1.
There are couple of log files that you can send me, if it exceeds the
attachment size restriction of this mailing list, to take a look at.
Change the loglevel to debug in sshd_config file. Then restart sshd.
Now try to ssh in from a remote client. Collect all the logs related
to `auth.*' (assuming your syslog fasciliy on sshd_config is set to
auth) and post it here. You may also post the ssh_config of the remote
client and sshd_config of the sshd server. I can use those test on my
side.
Also make sure you do have a local user account and it is not locked.
You must need a local account even though the authentication is done
thru tacacs server.
I am wondering if I am missing something in the sshd_config
configuration. Or is the interaction between the pam and sshd incorrect?
Gary
Asif Iqbal wrote:
> On 8/1/06, Gary Schlachter <Gary.Schlachter@tavve.com> wrote:
>> Thank you for your reply. The PAM is getting called which in turn
>> contacts the TACACS server. However, my problem is that OpenSSH is
>> authenticating the user against /etc/passwd instead of letting the user
>> be authenticated by the TACACS server. I am looking for a way to
>> configure SSH to stop the /etc/passwd authentication. When the user is
>> in /etc/passwd a but does not have a local password and is defined on
>> the TACACS server, TACACS authenticates the user correctly. I am
>> looking for a way to not have to configure the same user id on both the
>> TACACS server and the local system.
>
> I am using PAM with Radius Server Auth. So we should have similar setup.
>
> This is all I have in /etc/pam.conf (Solaris) for sshd to use only one
> pam_radius module and no other pam libraries.
>
> sshd auth required pam_radius_auth.so debug
>
> You may be using other pam libraries--specially the library that talks
> to /etc/passwd.
>
>> BTW, I am the PAM developer.
>>
>> Thanks,
>> Gary
>>
>> Asif Iqbal wrote:
>> > On 7/27/06, Gary Schlachter <Gary.Schlachter@tavve.com> wrote:
>> >> I know this question has been asked several times over the
>> years
>> >> but I have not seen a definitive answer/solution if one exists.
>> If one
>> >> does not exist or I need to develop one, then I can stop looking!
>> I am
>> >> attempting to integrate a Tacacs+ PAM with OpenSSH. I would like to
>> >> have the PAM authenticate the User ID as well as the password.
>> Thus the
>> >> users do not exist in /etc/passwd. I am not using NIS or any other
>> >> system for user ids. The Tacacs server is the only place the user
>> ids
>> >> exist. Ultimately when the user authenticates via Tacacs, I will
>> switch
>> >> the user to a known user in /etc/passwd and provide the logging in
>> user
>> >> with a specific TTY interface via the shell. When attempting this on
>> >> linux with OpenSSH 4.3p2 compiled with with_pam and seemingly the
>> >> correct sshd_config options, I received the infamous
>> >
>> > This is how I test
>> >
>> > Make sure ldd to sshd shows pam library in the list
>> >
>> > Modify the sshd_config file with the following two parameters
>> >
>> > Syslog Fascility auth
>> > Loglevel Debug
>> >
>> > restart OpenSSH
>> >
>> > touch a file /var/log/sshd.log.
>> >
>> > modify the syslog.conf with auth.debug point to /var/log/sshd.log and
>> > restart syslog.
>> >
>> > Now ssh with your tacacs account and see if your tacacs server
>> > receiving any connection logs from you as well as your
>> > /var/log/sshd.log file.
>> >
>> > If all fails I would ask the tacacs pam module developer about the
>> issue.
>> >
>> >
>> >>
>> >> Thanks in advance,
>> >> Gary
>> >>
>> >>
>> >
>> >
>>
>>
>
>
--
Asif Iqbal
PGP Key: 0xE62693C5 KeyServer: pgp.mit.edu
