[Samba] Accessing a guest share from Windows 10 gives System error 5 on some computers

Kai Ruhnau kai.ruhnau at target-sg.com
Wed Jul 19 06:35:31 UTC 2017


> I have an embedded instrument running samba 4.4.5 or 4.6.2 that connect to Windows / Mac / Linux via USB RNDIS / CDC Ethernet.
> On those instrument, there's a single share that is configured for guest access without password:
> [global]
>    log level = 10
>    workgroup = DATA
>    server string = Samba Server
>    log file = /var/log/samba/log.%m
>    max log size = 50
>    security = user
>    map to guest = Bad User
> [data]
>    path = /var/db/instrument-data
>    available = yes
>    browsable = yes
>    public = yes
>    writable = no
> Locally on the instrument, I can run `smbclient -N -L localhost` and see that share.
> The behavior is consistent on a per-computer basis. I can either access the share on any instrument without problems on one computer, or on another computer I cannot and the symptom is a `net view <instrument-name>` returning "System error 5, Access denied".
> The computers currently run a mix of Windows 10's Anniversary Update (14393) or Creators Update (15063) and there doesn't seem to be a correlation regarding that.
> I tcpdumped both types of sessions, and these show that the Windows Client forcefully closes the TCP connection (NT_STATUS_CONNECTION_RESET) right  after receiving `NTLMSSP_CHALLENGE` before a working client would send `NTLMSSP_AUTH` with a user.
> I have checked setting `AllowInsecureGuestAuth` in the geristry without any effect.

Isn't there anything I could try next?

Best regards
Kai Ruhnau
Software Manager
T:+49 202 769302 19

Target Systemelektronik GmbH & Co. KG
Heinz-Fangman-Straße 4
42287 Wuppertal

Amtsgericht Wuppertal HRA 23898
Persönlich haftende Gesellschafterin
Target Systemelektronik Beteiligungs GmbH
Heinz-Fangman-Straße 4, 42287 Wuppertal
Amtsgericht Wuppertal HRB 25346
Geschäftsführer: Jürgen Stein

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