AD group Auth

15 Aug 2019

      Hi Guys

I am using CentOS Linux release 7.6.1810 (Core) with all repository
installed binaries

[root@freeradpoc ~]# rpm -qa | egrep 'freeradius|samba|smb'
samba-common-4.8.3-4.el7.noarch
libsmbclient-4.8.3-4.el7.x86_64
samba-winbind-modules-4.8.3-4.el7.x86_64
freeradius-doc-3.0.13-10.el7_6.x86_64
freeradius-utils-3.0.13-10.el7_6.x86_64
samba-client-libs-4.8.3-4.el7.x86_64
samba-client-4.8.3-4.el7.x86_64
samba-libs-4.8.3-4.el7.x86_64
samba-winbind-clients-4.8.3-4.el7.x86_64
freeradius-3.0.13-10.el7_6.x86_64
freeradius-krb5-3.0.13-10.el7_6.x86_64
samba-common-libs-4.8.3-4.el7.x86_64
nagios-plugins-disk_smb-2.2.1-16.20180725git3429dad.el7.x86_64
samba-common-tools-4.8.3-4.el7.x86_64
samba-4.8.3-4.el7.x86_64
freeradius-ldap-3.0.13-10.el7_6.x86_64
samba-winbind-4.8.3-4.el7.x86_64
[root@freeradpoc ~]#

I configured the winbind and joined it to the AD domain
I configured Freeradius to use mschap with ntlm_auth to authenticate the
users from AD

This worked fine.

I am now trying to configure the system to only allow authentication if a
user belongs to a specific group on AD

Below is my config that I added to the /etc/raddb/sites-enabled/default
file in the post-auth section
----- ----- snip ----- -----
#  Post-Authentication
#  Once we KNOW that the user has been authenticated, there are
#  additional steps we can take.
post-auth {
        if (Group == "Store_WiFi_Access") {
          noop
        }
        else {
          reject
        }
        #
        #  If you need to have a State attribute, you can
        #  add it here.  e.g. for later CoA-Request with
        #  State, and Service-Type = Authorize-Only.
----- ----- snip ----- -----

I am getting the following in the radiusd -X output

----- ----- snip ----- -----
Ready to process requests
(0) Received Access-Request Id 89 from 127.0.0.1:58652 to 127.0.0.1:1812
length 134
(0)   User-Name = "USER"
(0)   NAS-IP-Address = 172.20.191.111
(0)   NAS-Port = 0
(0)   Message-Authenticator = 0xdb40186f7a789c28e189db46fe6f52de
(0)   MS-CHAP-Challenge = 0xa73861b073389f3e
(0)   MS-CHAP-Response =
0x0001000000000000000000000000000000000000000000000000419d61181a4b646dee7a6c3639ce222a2f6445523d6f6f4b
(0) # Executing section authorize from file /etc/raddb/sites-enabled/default
(0)   authorize {
(0)     policy filter_username {
(0)       if (&User-Name) {
(0)       if (&User-Name)  -> TRUE
(0)       if (&User-Name)  {
(0)         if (&User-Name =~ / /) {
(0)         if (&User-Name =~ / /)  -> FALSE
(0)         if (&User-Name =~ /@[^@]*@/ ) {
(0)         if (&User-Name =~ /@[^@]*@/ )  -> FALSE
(0)         if (&User-Name =~ /\.\./ ) {
(0)         if (&User-Name =~ /\.\./ )  -> FALSE
(0)         if ((&User-Name =~ /@/) && (&User-Name !~ /@(.+)\.(.+)$/))  {
(0)         if ((&User-Name =~ /@/) && (&User-Name !~ /@(.+)\.(.+)$/))   ->
FALSE
(0)         if (&User-Name =~ /\.$/)  {
(0)         if (&User-Name =~ /\.$/)   -> FALSE
(0)         if (&User-Name =~ /@\./)  {
(0)         if (&User-Name =~ /@\./)   -> FALSE
(0)       } # if (&User-Name)  = notfound
(0)     } # policy filter_username = notfound
(0)     [preprocess] = ok
(0)     [chap] = noop
(0) mschap: Found MS-CHAP attributes.  Setting 'Auth-Type  = mschap'
(0)     [mschap] = ok
(0)     [digest] = noop
(0) suffix: Checking for suffix after "@"
(0) suffix: No '@' in User-Name = "USER", looking up realm NULL
(0) suffix: No such realm "NULL"
(0)     [suffix] = noop
(0) eap: No EAP-Message, not doing EAP
(0)     [eap] = noop
(0) files: users: Matched entry DEFAULT at line 1
(0)     [files] = ok
(0)     [expiration] = noop
(0)     [logintime] = noop
(0) pap: WARNING: No "known good" password found for the user.  Not setting
Auth-Type
(0) pap: WARNING: Authentication will fail unless a "known good" password
is available
(0)     [pap] = noop
(0)   } # authorize = ok
(0) Found Auth-Type = mschap
(0) # Executing group from file /etc/raddb/sites-enabled/default
(0)   authenticate {
(0) mschap: Client is using MS-CHAPv1 with NT-Password
(0) mschap: Executing: /bin/ntlm_auth --request-nt-key
--username=%{%{Stripped-User-Name}:-%{%{User-Name}:-None}}
--challenge=%{%{mschap:Challenge}:-00}
--nt-response=%{%{mschap:NT-Response}:-00} --domain=%{mschap:NT-Domain}:
(0) mschap: EXPAND
--username=%{%{Stripped-User-Name}:-%{%{User-Name}:-None}}
(0) mschap:    --> --username=USER
(0) mschap: mschap1: a7
(0) mschap: EXPAND --challenge=%{%{mschap:Challenge}:-00}
(0) mschap:    --> --challenge=a73861b073389f3e
(0) mschap: EXPAND --nt-response=%{%{mschap:NT-Response}:-00}
(0) mschap:    -->
--nt-response=419d61181a4b646dee7a6c3639ce222a2f6445523d6f6f4b
(0) mschap: ERROR: No NT-Domain was found in the User-Name
(0) mschap: EXPAND --domain=%{mschap:NT-Domain}
(0) mschap:    --> --domain=
(0) mschap: Program returned code (0) and output 'NT_KEY:
475C9726A51B871F423CD04286A9F0E4'
(0) mschap: adding MS-CHAPv1 MPPE keys
(0)     [mschap] = ok
(0)   } # authenticate = ok
(0) # Executing section post-auth from file /etc/raddb/sites-enabled/default
(0)   post-auth {
(0)     if (Group == "Store_WiFi_Access") {
(0)     Failed resolving GID: No error
(0)     if (Group == "Store_WiFi_Access")  -> FALSE
(0)     else {
(0)       [reject] = reject
(0)     } # else = reject
(0)   } # post-auth = reject
(0) Using Post-Auth-Type Reject
(0) # Executing group from file /etc/raddb/sites-enabled/default
(0)   Post-Auth-Type REJECT {
(0) attr_filter.access_reject: EXPAND %{User-Name}
(0) attr_filter.access_reject:    --> USER
(0) attr_filter.access_reject: Matched entry DEFAULT at line 11
(0)     [attr_filter.access_reject] = updated
(0)     [eap] = noop
(0)     policy remove_reply_message_if_eap {
(0)       if (&reply:EAP-Message && &reply:Reply-Message) {
(0)       if (&reply:EAP-Message && &reply:Reply-Message)  -> FALSE
(0)       else {
(0)         [noop] = noop
(0)       } # else = noop
(0)     } # policy remove_reply_message_if_eap = noop
(0)   } # Post-Auth-Type REJECT = updated
(0) Delaying response for 1.000000 seconds
Waking up in 0.2 seconds.
Waking up in 0.7 seconds.
(0) Sending delayed response
(0) Sent Access-Reject Id 89 from 127.0.0.1:1812 to 127.0.0.1:58652 length
20
Waking up in 3.9 seconds.
(0) Cleaning up request packet ID 89 with timestamp +4
Ready to process requests
---- ----- snip ----- -----

I need to find out why am I getting this message in the debug output
{Failed resolving GID: No error}

And if I am using the wrong variable to determine the AD group { if (Group
== "Store_WiFi_Access")}

I checked the OS /var/log/messages file to see if there is a clue why this
is failing but nothing is written to this file.

Any help will be helpful at the moment.

Regards
*Alex Jordaan*
Linux Engineer

-- 
Disclaimer: 
https://www.shopriteholdings.co.za/copyright-etc--statements/email-disclaime... 
<http://www.shopriteholdings.co.za/copyright-etc--statements/email-disclaimer.html>