Issue with VLAN Assignment during 802.1x Authentication in RADIUS (Incorrect LDAP Query)

UCS - Univention Corporate Server
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#1

Hello,

I’ve encountered an issue with VLAN assignment for users authenticating via 802.1x. While the users authenticate successfully, the VLAN is not being assigned. After reviewing the Freeradius debug logs, I noticed that the Tunnel-Private-Group-Id attribute is not included in the Reply-Message. Further investigation revealed that the LDAP query is constructed incorrectly, using the %{User-Name} variable, which includes the domain name and a backslash (\\), resulting in a malformed query like uid=domainname\5cusername.

Example from the Freeradius debug log:

(25)     if ("%{tolower:%{request:User-Name}}" =~ /^host\/(.*)\.domainname.example.com/)  -> FALSE
(25)     if (control:Auth-Type == "CSID" || (Calling-Station-Id && EAP-Message && control:Cleartext-Password)) {
(25)     if (control:Auth-Type == "CSID" || (Calling-Station-Id && EAP-Message && control:Cleartext-Password))  -> FALSE
(25)     if ("%{ldap:ldap:///dc=domainname,dc=example,dc=com?uid?sub?(|(uid=%{User-Name})(macAddress=%{Calling-Station-Id}))}") {
rlm_ldap (ldap): Reserved connection (12)
(25)     Performing search in "dc=domainname,dc=example,dc=com" with filter "(|(uid=domainname\5cusername)(macAddress=0C:37:96:<mask>))", scope "sub"
(25)     Waiting for search result...
(25)     Search returned no results
rlm_ldap (ldap): Released connection (12)
(25)     EXPAND %{ldap:ldap:///dc=domainname,dc=example,dc=com?uid?sub?(|(uid=%{User-Name})(macAddress=%{Calling-Station-Id}))}
(25)        --> 
(25)     if ("%{ldap:ldap:///dc=domainname,dc=example,dc=com?uid?sub?(|(uid=%{User-Name})(macAddress=%{Calling-Station-Id}))}")  -> FALSE

As a result, the query does not return any results, and the VLAN is not assigned.

Solution: I modified the Freeradius configuration /etc/freeradius/3.0/sites-enabled/default by replacing the %{User-Name} variable with %{Stripped-User-Name} to ensure the LDAP query is constructed correctly without the domain name and backslash:

if ("%{ldap:ldap:///dc=domainname,dc=example,dc=com?uid?sub?(|(uid=%{Stripped-User-Name})(macAddress=%{Calling-Station-Id}))}") {

After this change, RADIUS started returning the correct VLAN ID:

(10)   Tunnel-Type := VLAN
(10)   Tunnel-Medium-Type := IEEE-802
(10)   Tunnel-Private-Group-Id := "3156"

Question: Is this a bug in UCS (a configuration or logic issue in the LDAP query), or am I missing something? Could there be any unintended side effects from replacing %{User-Name} with %{Stripped-User-Name}?

Thank you in advance for your assistance!

#2

Here’s a patch of my config:

--- sites-available/default     2024-09-05 12:34:34.546155709 +0300
+++ sites-available/default-changed     2024-09-05 12:39:16.774779933 +0300
@@ -832,17 +832,17 @@
     # Check if the user or machine exists and do post-auth actions
     # else do nothing in post-auth
     # This way we also make sure that we do not change the VLAN ID again if the non-EAP-auth (MAC address auth) succeeded before (see above)
-    if ("%{ldap:ldap:///dc=domainname,dc=example,dc=com?uid?sub?(|(uid=%{User-Name})(macAddress=%{Calling-Station-Id}))}") {
+    if ("%{ldap:ldap:///dc=domainname,dc=example,dc=com?uid?sub?(|(uid=%{Stripped-User-Name})(macAddress=%{Calling-Station-Id}))}") {
 
         # For known users as well for known machines we take the vlan-id from the group the user/machine is member of.
         # In case there are assignments for several groups the first vlan-id is automatically taken.
-        if ("%{ldap:ldap:///dc=domainname,dc=example,dc=com?univentionVlanId?sub?(&(|(memberUid=%{User-Name})(macAddress=%{Calling-Station-Id}))(univentionObjectType=groups/group)(univentionVlanId=*)(univentionNetworkAccess=1))}") {
+        if ("%{ldap:ldap:///dc=domainname,dc=example,dc=com?univentionVlanId?sub?(&(|(memberUid=%{Stripped-User-Name})(macAddress=%{Calling-Station-Id}))(univentionObjectType=groups/group)(univentionVlanId=*)(univentionNetworkAccess=1))}") {
 
             update reply {
                 Reply-Message := "DEBUG: Assigning VLAN-ID from user / computer object"
                 Tunnel-Type := VLAN
                 Tunnel-Medium-Type := IEEE-802
-                Tunnel-Private-Group-Id := "%{ldap:ldap:///dc=domainname,dc=example,dc=com?univentionVlanId?sub?(&(|(memberUid=%{User-Name})(memberUid=%{1}))(univentionObjectType=groups/group)(univentionVlanId=*)(univentionNetworkAccess=1))}"
+                Tunnel-Private-Group-Id := "%{ldap:ldap:///dc=domainname,dc=example,dc=com?univentionVlanId?sub?(&(|(memberUid=%{Stripped-User-Name})(memberUid=%{1}))(univentionObjectType=groups/group)(univentionVlanId=*)(univentionNetworkAccess=1))}"
 
 
             }
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