[cups] Printing with SMB-Kerberos in CUPS on Ubuntu 16.04

[Van Svensson]

Hello,

I'm running Ubuntu 14.04 LTS and printing using SMB-Kerberos through CUPS 1.7.2-0ubuntu1.8 (default) and everything works. However, on another computer I have installed Ubuntu 16.04 LTS with CUPS 2.1.3-4 (default) but the printing does no longer work.

On both 14.04 and 16.04 Samba seem to be the same version, 2:4.3.11+dfsg-0ubuntu0.14.04.10 and 2:4.3.11+dfsg-0ubuntu0.16.04.9.

For both 14.04 and 16.04 I have that
* "AuthInfoRequired negotiate" is set in /etc/cups/printers.conf
* /usr/lib/cups/backend/smb is a symbolic link to /usr/bin/smbspool_krb5_wrapper
* /usr/bin/smbspool_krb5_wrapper is chmod 700

Can somebody please help me track down the problem from the CUPS error messages in /var/log/cups/error_log from the 16.04 installation? (I have set "LogLevel debug" in /etc/cups/cupsd.conf)

D [05/Aug/2017:12:52:04 +0200] [Job 89] SMBSPOOL_KRB5 - Started with uid=0
D [05/Aug/2017:12:52:04 +0200] [Job 89] SMBSPOOL_KRB5 - AUTH_INFO_REQUIRED=negotiate
D [05/Aug/2017:12:52:04 +0200] [Job 89] SMBSPOOL_KRB5 - Switching to gid=1000
D [05/Aug/2017:12:52:04 +0200] [Job 89] SMBSPOOL_KRB5 - Switching to uid=1000
D [05/Aug/2017:12:52:04 +0200] [Job 89] SMBSPOOL_KRB5 - Setting KRB5CCNAME to \'FILE:/tmp/krb5cc_1000\'
D [05/Aug/2017:12:52:04 +0200] [Client 12] HTTP_STATE_WAITING Closing for error 32 (Broken pipe)
D [05/Aug/2017:12:52:04 +0200] [Client 12] Closing connection.
D [05/Aug/2017:12:52:04 +0200] cupsdSetBusyState: newbusy="Printing jobs and dirty files", busy="Printing jobs and dirty files"
E [05/Aug/2017:12:52:04 +0200] [Job 89] Could not determine network interfaces, you must use a interfaces config line

I see that double backslashes are used in 16.04 when SMBSPOOL_KRB5 is setting KRB5CCNAME, can that cause this problem?
Ubuntu 16.04 /var/log/cups/error_log: SMBSPOOL_KRB5 - Setting KRB5CCNAME to \'FILE:/tmp/krb5cc_1000\'
Ubuntu 14.04 /var/log/cups/error_log: SMBSPOOL_KRB5 - Setting KRB5CCNAME to 'FILE:/tmp/krb5cc_1000'

Do you have any idea about what the error "HTTP_STATE_WAITING Closing for error 32 (Broken pipe)" can tell me in this situation when it is printed right after SMBSPOOL_KRB5 has set KRB5CCNAME?

Also wondering about why I get this right after the above error: "Could not determine network interfaces, you must use a interfaces config line"

Thanks / Van