[tac_plus] Issue with Cisco switch authentication against Microsoft Active Directory

[Hailu Meng]

Hi all,

I'm trying to set up tac_plus in CentOS 5.3. tac_plus has been compiled with
pam and tcp_wrapper. I configured my switch as below:

aaa new-model
aaa authentication login default group tacacs+ local-case
aaa authentication enable default group tacacs+ enable
aaa authorization exec default tacacs+
aaa accounting exec default start-stop tacacs+
aaa accounting network start-stop tacacs+
tacacs+ host 10.0.0.11
tacacs+ key mykey

I configured /etc/tac_plus.conf to use local setting firstly. It worked.
Then I tried to use pam with ldap to authenticate against the microsoft
active directory. I snifferred the traffic and saw there was an error when
my tacacs server was doing query against Active Directory. The error
is *problem
2001* (*NO_OBJECT*).

Do you guys have similar problem when you set up this kind of
authentication? I listed the main configuration files below:
**************************************************************
/etc/pam.d/tac_plus

#%PAM-1.0
auth       include      system-auth
account    required     pam_nologin.so
account    include      system-auth
password   include      system-auth
session    optional     pam_keyinit.so force revoke
session    include      system-auth
session    required     pam_loginuid.so

*********************************************
/etc/pam.d/system-auth

#%PAM-1.0
# This file is auto-generated.
# User changes will be destroyed the next time authconfig is run.
auth        required      pam_env.so
auth        sufficient    pam_unix.so nullok try_first_pass
auth        requisite     pam_succeed_if.so uid >= 500 quiet
auth        sufficient    pam_ldap.so use_first_pass
auth        required      pam_deny.so

account     required      pam_unix.so broken_shadow
account     sufficient    pam_localuser.so
account     sufficient    pam_succeed_if.so uid < 500 quiet
account     [default=bad success=ok user_unknown=ignore] pam_ldap.so
account     required      pam_permit.so

password    requisite     pam_cracklib.so try_first_pass retry=3
password    sufficient    pam_unix.so md5 shadow nullok try_first_pass
use_authtok
password    sufficient    pam_ldap.so use_authtok
password    required      pam_deny.so

session     optional      pam_keyinit.so revoke
session     required      pam_limits.so
session     [success=1 default=ignore] pam_succeed_if.so service in
crond quiet use_uid
session     required      pam_unix.so
session     required      pam_mkhomedir.so skel=/etc/skel/ umask=0077
session     optional      pam_ldap.so

*******************************************************8
/etc/ldap.conf


host 10.0.0.100
base    ou=security groups,dc=hq,dc=corp,dc=myhouse,dc=com
binddn  cn=network services,ou=security groups,dc=hq,dc=corp,dc=myhouse,dc=com
#bindpw  ohsosecret  # no secret set
scope   sub
ssl     no


nss_schema              rfc2307bis
nss_base_passwd         ou=security groups,dc=hq,dc=corp,dc=myhouse,dc=com?sub
nss_base_shadow         ou=security groups,dc=hq,dc=corp,dc=myhouse,dc=com?sub
nss_base_group          ou=security groups,dc=hq,dc=corp,dc=myhouse,dc=com?sub

referrals       no  # otherwise it goes freakishly slow

I linked /etc/openldap/ldap.conf to /etc/ldap.conf. I didn't enable ssl for
ldap.

I think the problem could be in the configuration of ldap.conf or it doesn't
match the configuration in Active Directory. In my AD, I have "security
groups" OU and in this OU I have "network services" group.
Maybe the issue also stays in nss mapping? I searched some articles. It
seems like nss mapping must be correct to authenticate through Linux box
against Active Directory.

Another question about active directory is: Do I need create a separate OU
to hold the user accounts who will have rights to login Cisco devices? I saw
someone said the user account in tacacs server must not be in other groups.
If the separate OU is needed and the user must be only in this new OU, it
will lose the flexibility to use the current Active Directory which is
already configured.

Please give me some help on this. Very appreciated.

Thanks.

Lou
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