ntlmssp_handle_neg_flags: Got challenge flags[0x60898205] - possible downgrade detected! missing_flags[0x00000010] - NT code 0x80090302

I'm trying to access SMB/CIFS resource on NetApp, using following and getting error:

$ cat /etc/redhat-release 
CentOS Linux release 7.2.1511 (Core) 
$ rpm -qa | grep ^samba-
samba-client-4.2.10-6.el7_2.x86_64
samba-libs-4.2.10-6.el7_2.x86_64
samba-common-libs-4.2.10-6.el7_2.x86_64
samba-common-4.2.10-6.el7_2.noarch
samba-client-libs-4.2.10-6.el7_2.x86_64
samba-common-tools-4.2.10-6.el7_2.x86_64
$ smbclient //X/Y$ -U DOMAIN/user -L
Enter DOMAIN/user's password: 
ntlmssp_handle_neg_flags: Got challenge flags[0x60898205] - possible downgrade detected! missing_flags[0x00000010] - NT code 0x80090302
  NTLMSSP_NEGOTIATE_SIGN
SPNEGO(ntlmssp) login failed: NT code 0x80090302
session setup failed: NT code 0x80090302
$ 

I'm trying to use following with my smbclient:

--option==

Set the smb.conf(5) option "<name>" to value "<value>" from the command line. This overrides compiled-in defaults and options read from the configuration file.

yet, I'm still unable to access resource on server as I'm doing it wrong:

$ smbclient //X/Y$ -U DOMAIN/user -L --option='client ntlmv2 auth'=no
Enter DOMAIN/user's password: 
Connection to --option=client ntlmv2 auth=no failed (Error NT_STATUS_UNSUCCESSFUL)
$ 

What is right way to set client ntlmv2 auth=no via --option in smbclient?

You may want to disable spnego within ntlmssp, with default params :

# smbclient -L //MY_SERVER -U MY_USER Enter MY_USER's password: ntlmssp_handle_neg_flags: Got challenge flags[0x60898205] - possible downgrade detected! missing_flags[0x00000010] - NT code 0x80090302 NTLMSSP_NEGOTIATE_SIGN

with spnego disabled :

# smbclient -L //MY_SERVER -U MY_USER --option='client use spnego=no'

worked for me.