NAS SMB server not accepting packets > 65k size. Does SMB2->Negotiate_Protocol_Response->Max_Write_Size = 65536 Matters?

amit kumar amitkuma at redhat.com
Sun Apr 30 15:25:13 UTC 2017


Hello,

This is situation:

*    [netApps SMB-server]                     [RHEL-7.1-Client]*
                |      =SMB 2/3=                           |
                |                                          sending
data>65k Fail
                |                                          sending
data<65k Passes 
Max Write/Read Size[65535]                                               

*From Packet Captures*:
1. For FSCTL_VALIDATE_NEGOTIATE_INFO message:
NAS returned STATUS_NOT_SUPPORTED & RHEL client drops the transaction.

Though these are filters on NAS Server:

NAS_Server::*> vserver cifs options show 
                           ...
Max Buffer Size for SMB1 Message: 65535
	            SMB2 Enabled: true
                    SMB3 Enabled: true
                    WINS Servers: 


2. SMB2->Negotiate_Protocol_Response->Max_Write_Size = 65536,
Max_Read_Size = 65536
	*[Windows SMB-server]                     [RHEL-7.1-Client]*
                |      =SMB 2/3=                           |
                |                                       sending data>65k
Passes   Max Write/Read Size[8388608]                                
                


*From Packet Captures*:
1. For FSCTL_VALIDATE_NEGOTIATE_INFO message:
Win12 returned STATUS_SUCCESS












2. SMB2->Negotiate_Protocol_Response->Max_Write_Size = 8388608,
Max_Read_Size = 8388608
	*        **[RHEL SMB-server]                     [RHEL-7.1-Client]*
                |      =SMB 2/3=                           |
                |                                       sending data>65k
Passes     
Max Write/Read Size[8388608]


*From Packet Captures*:
1. For FSCTL_VALIDATE_NEGOTIATE_INFO message:
RHEL returned STATUS_SUCCESS












2. SMB2->Negotiate_Protocol_Response->Max_Write_Size = 8388608,
Max_Read_Size = 8388608


My queries:
1. Can server accept/send more than 65K sized packet, if
SMB2->Negotiate_Protocol_Response->Max_Write_Size = 65536, Max_Read_Size
= 65536?
    Again, on NAS, On cifs-mounted shares packets > 65k succeed to get
transferred..
2. If SMB-server sends STATUS_NOT_SUPPORTED for
FSCTL_VALIDATE_NEGOTIATE_INFO, Is it expected to carry the transaction
further?

-- 
Thanks
Amit Kumar
!!If you stumble, get back up. 
What happened yesterday, no longer matters.
Today is another day to move closer to your GOAL!!



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