[Wolves] Logging onto a Linux Mint machine

[Adam Sweet]

On 22/04/2019 02:51, Mark Ellse via Wolves wrote:
> I've recently built a Linux Mint machine for a second backup server. Samba
> installs by sharing a folder. Guest access, if I set it, works: so sharing
> is working. But user access only won't work because it won't give access if
> I to a given username and password and I've checked with creating another
> user "username" and "password".
> 
> I know that this should work because I have another similar machine which
> works fine as a server for Windows File History from my main Windows 10
> machine so I think I am doing something daft. I suspect that it is because
> I am not using the full username. As well as "username" I have also used
> "machinename/username" etc.
> 
> I'd be grateful for any hints.

Hi Mark

Glad to see you're still out there :)

I'm not a Samba expert but I'd need to know the following to be able to
help at all:

* What samba version is the server?
* What samba version (or Windows OS) is the client?
* What errors are you seeing when connecting fails?

My first thought was that this might be an SMB protocol version issue.
The old SMBv1 protocol which offers Network Neighbourhood style share
auto-discovery and browsing is insecure (see WannaCry and Petya) and no
longer enabled by default in Windows, but SMBv1 was still the default
protocol version in Samba last time I checked about 18 months ago.

When you try to connect an SMBv2 or SMBv3 only client to a server
talking SMB1 or vice versa, it will fail to negotiate a protocol and
give you some errors like:

# smbclient -L 127.0.0.1 -U adam

smb1cli_req_writev_submit: called for dialect[SMB3_11] server[127.0.0.1]
Error returning browse list: NT_STATUS_REVISION_MISMATCH
Reconnecting with SMB1 for workgroup listing.
protocol negotiation failed: NT_STATUS_INVALID_NETWORK_RESPONSE
Failed to connect with SMB1 -- no workgroup available

...but if that were the problem then your guest account wouldn't work
either.

I know there were plans to disable SMBv1 by default in Samba but I don't
know if that's the case yet. Nevertheless, for disabling SMBv1, take a
look at:

https://blogs.technet.microsoft.com/filecab/2016/09/16/stop-using-smb1/

https://www.cyberciti.biz/faq/how-to-configure-samba-to-use-smbv2-and-disable-smbv1-on-linux-or-unix/

In any case, I'd recommend working out what Samba versions you're using
for server and client:

samba -V
(or maybe samba-tool -V or smbclient -V on a Linux client)

And also looking at the server's Samba logs in:

/var/log/samba/log.smbd
/var/log/samba/log.nmbd
/var/log/samba/log.<your client's address>

Hopefully you'll see some errors that give you a clue about what's going
on. As always the Arch wiki is useful and fairly detailed, though being
about Arch Linux it's obviously not applicable verbatim to Mint:

https://wiki.archlinux.org/index.php/Samba

Without knowing the Samba versions, what errors are being logged or
errors you're seeing when it fails to connect, it's difficult to say
anything.

Adam