Hi all,

I've got a Dovecot v2.3.3 IMAP with GSSAPI auth set up. This server is in main domain, 'contoso.com'. I also have several subdomains.

My problem is usernames with GSSAPI authentication:

When I try to login as 'user' or as 'user@CONTOSO.COM' - everything works. But, 'user@contoso.com' auth fails. But when I try to login as subdomain user, 'user2' - it fails to login. 'user2@sub.contoso.com' fails also. However, 'user2@SUB.CONTOSO.COM' works ok.

It looks like PAM uses domain part of login as Kerberos realm name, regardless of Kerberos domain-realm mapping. Also, if domain part is not specified, PAM (Kerberos?) fails to determine non-default realm.

What am I missing? Is there a way to use traditional 'user@domain' login names with PAM/GSSAPI, instead of Kerberos ticket names? Or maybe to tell PAM module to convert domain part of username to uppercase before using?

Thanks on any help or advice.

===== dovecot.conf: ===== auth_mechanisms = gssapi plain login external auth_gssapi_hostname = "$ALL" auth_krb5_keytab = /etc/krb5.keytab auth_default_realm = passdb { driver = pam args = cache_key=%d%r%n failure_show_msg=yes dovecot } userdb { driver = static args = uid=502 gid=502 home=/var/vmail/%L{auth_domain}/%L{auth_username} mail=maildir:/var/vmail/%L{auth_domain}/%L{auth_username}/Maildir allow_all_users=yes }

===== pam.d/dovecot: ===== auth sufficient pam_krb5.so use_first_pass account [default=bad success=ok user_unknown=ignore] pam_krb5.so password sufficient pam_krb5.so use_authtok session optional pam_krb5.so

===== krb5.conf: ===== [libdefaults] default_realm = CONTOSO.COM dns_lookup_realm = true dns_lookup_kdc = true [realms] CONTOSO.COM = { kdc = dc.contoso.com:88 admin_server = dc.contoso.com:749 }

[domain_realm] contoso.com = CONTOSO.COM .contoso.com = CONTOSO.COM sub.contoso.com = CONTOSO.COM .sub.contoso.com = CONTOSO.COM SUB.CONTOSO.COM = CONTOSO.COM .SUB.CONTOSO.COM = CONTOSO.COM

[appdefaults] pam = { ticket_lifetime = 36000 renew_lifetime = 36000 forwardable = true krb4_convert = false }

===== klist server ==== Default principal: imap/mail2.contoso.com@CONTOSO.COM

===== klist client ==== Default principal: user2@SUB.CONTOSO.COM

===== Logging in with user2@SUB.CONTOSO.COM - OK: =====

auth: Debug: client in: AUTH 1 GSSAPI service=imap secured=tls session=.... auth: Debug: gssapi(?,192.168.....,<MR1yvq6DftfAqAoP>): Using all keytab entries auth: Debug: client passdb out: CONT 1 auth: Debug: client in: CONT<hidden> auth: Debug: gssapi(user2@sub.contoso.com,192.168....,<MR1yvq6DftfAqAoP>): security context state completed. auth: Debug: client passdb out: CONT 1 YIGVB.... auth: Debug: client in: CONT<hidden> auth: Debug: gssapi(user2@sub.contoso.com,192.168.....,<MR1yvq6DftfAqAoP>): Negotiated security layer auth: Debug: client passdb out: CONT 1 BQQF/..... auth: Debug: client in: CONT<hidden> auth: Debug: pam(user2@sub.contoso.com,192.168.....,<MR1yvq6DftfAqAoP>): passdb doesn't support credential lookups auth: Debug: gssapi(user2@sub.contoso.com,192.168.....,<MR1yvq6DftfAqAoP>): skipping passdb: mechanism filtered auth: Debug: client passdb out: OK 1 user=user2@sub.contoso.com original_user=user2@SUB.CONTOSO.COM

===== Logging in with user2@sub.contoso.com - FAIL: =====

auth: Debug: client in: AUTH 1 GSSAPI service=imap secured=tls session=... auth: Debug: gssapi(?,192.168....,<Hgh4zq6DhNfAqAoP>): Using all keytab entries auth: Debug: client passdb out: CONT 1 auth: Debug: client in: CONT<hidden> auth: Debug: gssapi(user2@sub.contoso.com,192.168....,<Hgh4zq6DhNfAqAoP>): security context state completed. auth: Debug: client passdb out: CONT 1 YIGVB..... auth: Debug: client in: CONT<hidden> auth: Debug: gssapi(user2@sub.contoso.com,192.168....,<Hgh4zq6DhNfAqAoP>): Negotiated security layer auth: Debug: client passdb out: CONT 1 BQQF/..... auth: Debug: client in: CONT<hidden> auth: Debug: pam(user2@sub.contoso.com,192.168.....,<Hgh4zq6DhNfAqAoP>): passdb doesn't support credential lookups auth: Debug: gssapi(user2@sub.contoso.com,192.168.....,<Hgh4zq6DhNfAqAoP>): skipping passdb: mechanism filtered auth: Debug: client passdb out: FAIL 1 user=user2@sub.contoso.com original_user=user2@SUB.CONTOSO.COM