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Bug 1807093

Summary: krb5_server failover doesn't work with unresolved server name in the list
Product: Red Hat Enterprise Linux 8 Reporter: Amith <apeetham>
Component: sssdAssignee: Paweł Poławski <ppolawsk>
Status: CLOSED DUPLICATE QA Contact: sssd-qe <sssd-qe>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 8.2CC: atikhono, grajaiya, jhrozek, lslebodn, mzidek, pbrezina, sgoveas, thalman, tscherf
Target Milestone: rcKeywords: Regression, Triaged
Target Release: 8.0Flags: pm-rhel: mirror+
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: sync-to-jira
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2021-08-25 07:27:07 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Amith 2020-02-25 15:19:11 UTC
Description of problem:

This issue is copied from 7.7 bug 1807033.

If one of the server name in the list for krb5_server is UNRESOLVED then failover doesn't work. 
Lets assume that two krb5 servers are valid and resolvable ie, Server1-valid.example.com, Server2-valid.example.com. 
The unresolved krb5 server name is invalid.example,com, then following examples work:

krb5_server = Server1-valid.example.com,Server2-valid.example.com
krb5_server = Server1-valid.example.com,_srv_
krb5_server = Server1-valid.example.com,10.16.200.11
krb5_server = 10.16.200.11,_srv_,Server1-valid.example.com,

However the below combinations fail to work:

krb5_server = Server1-valid.example.com,Server2-valid.example.com,invalid.example,com
krb5_server = Server1-valid.example.com,invalid.example,com
krb5_server = invalid.example,com,Server1-valid.example.com,10.16.200.11
krb5_server = invalid.example,com,Server2-valid.example.com,_srv_

Version-Release number of selected component (if applicable):
sssd-2.2.3-16.el8.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Setup a DNS server with valid KRB Server name and SRV records. 

A forward zone example would be:
-------------------------------
$TTL 604800
@       IN      SOA     Server1-valid.example.com. root.Server1-valid.example.com. (
                        2010050702 ; serial
                        604800 ; refresh
                        86400 ; retry
                        2419200 ; expire
                        10800 ; negative caching time
                        )
example.com.         IN NS  Server1-valid.example.com.
_ldap._tcp      IN SRV 1 0 389 Server1-valid
_kerberos._udp  IN SRV 0 0 88 Server1-valid
Server1-valid	IN A   10.19.34.83
Server2-valid   IN A   10.16.216.102
--------------------------------

2. Setup SSSD domain section with any one of the above krb5_server combination:

[domain/LDAP]
debug_level=0xFFF0
id_provider = ldap
ldap_uri = ldap://Server1-valid.example.com
ldap_search_base = dc=example,dc=com
auth_provider = krb5
krb5_realm = EXAMPLE.COM
krb5_server = invalid.example,com,Server1-valid.example.com
krb5_backup_server = Server2-valid.example.com
dns_discovery_domain = example.com

3. Restart SSSD service and execute a user login. You will see that user auth fails. 

Actual results:
User auth fails whenever UNRESOLVED server name is present in the list.

Expected results:
Failover should work even if one of the SERVER in the list is unresolved.

Additional info:

Comment 1 Pavel Březina 2020-03-05 16:26:25 UTC
*** Bug 1807083 has been marked as a duplicate of this bug. ***

Comment 3 Alexey Tikhonov 2021-03-08 14:32:00 UTC
*** Bug 1807074 has been marked as a duplicate of this bug. ***

Comment 7 RHEL Program Management 2021-08-25 07:27:07 UTC
After evaluating this issue, there are no plans to address it further or fix it in an upcoming release.  Therefore, it is being closed.  If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.

Comment 8 Alexey Tikhonov 2021-08-26 16:19:42 UTC
Pawel says the root cause is the same as in bz 1859315

*** This bug has been marked as a duplicate of bug 1859315 ***