Defaults for xenial (samba 4.3.11):
  client min protocol = CORE
  client max protocol = default (which is NT1 in this version of samba)

Defaults for artful (samba 4.6.7):
  client min protocol = CORE
  client max protocol = default (which is NT1 in this version of samba)

Defaults for bionic (samba 4.7.6):
  client min protocol = CORE
  client max protocol = default (which is SMB3_11 in this version of samba)

So before bionic, if you wanted a more secure protocol, you had to
specify it (like smbclient's -m SMB3 option).

Now in bionic, if you want a *less* secure protocol. you have to specify
it.

Ideally, computer browsing and actually connecting to shares should
happen with different protocol versions.

smbclient in bionic does a quick downgrade to NT1 when needed. Notice the 
"Reconnecting" message intertwined in the output below:
ubuntu@bionic-desktop:~$ smbclient -L xenial -N -m SMB3
Anonymous login successful

        Sharename       Type      Comment
        ---------       ----      -------
        print$          Disk      Printer Drivers
        public          Disk      Public share
        IPC$            IPC       IPC Service (xenial-desktop server (Samba, 
Ubuntu))
Reconnecting with SMB1 for workgroup listing.
Anonymous login successful

        Server               Comment
        ---------            -------

        Workgroup            Master
        ---------            -------
        UBUNTU               XENIAL


In artful, that downgrade does not happen, and we don't get the workgroup 
listing:
ubuntu@artful-desktop:~$ smbclient -L xenial -N -m SMB3
Anonymous login successful

        Sharename       Type      Comment
        ---------       ----      -------
        print$          Disk      Printer Drivers
        public          Disk      Public share
        IPC$            IPC       IPC Service (xenial-desktop server (Samba, 
Ubuntu))
Anonymous login successful

        Server               Comment
        ---------            -------

        Workgroup            Master
        ---------            -------
ubuntu@artful-desktop:~$ 


I suspect smbtree does the same. In bionic, where max protocol is SMB3_11 by 
default, it works out of the box. But in artful, if I set client max protocol 
to SMB3_11, it stops working:
ubuntu@artful-desktop:~$ testparm -s -v 2>/dev/null|grep "client max protocol"
        client max protocol = default
ubuntu@artful-desktop:~$ smbtree
UBUNTU
        \\XENIAL                        xenial-desktop server (Samba, Ubuntu)
                \\XENIAL\IPC$                   IPC Service (xenial-desktop 
server (Samba, Ubuntu))
                \\XENIAL\public                 Public share
                \\XENIAL\print$                 Printer Drivers
        \\BIONIC                        bionic-desktop server (Samba, Ubuntu)
                \\BIONIC\IPC$                   IPC Service (bionic-desktop 
server (Samba, Ubuntu))
                \\BIONIC\public                 Public share
                \\BIONIC\print$                 Printer Drivers
        \\ARTFUL                        artful-desktop server (Samba, Ubuntu)
                \\ARTFUL\IPC$                   IPC Service (artful-desktop 
server (Samba, Ubuntu))
                \\ARTFUL\public                 Public share
                \\ARTFUL\print$                 Printer Drivers
ubuntu@artful-desktop:~$ sudo vi /etc/samba/smb.conf 
ubuntu@artful-desktop:~$ testparm -s -v 2>/dev/null|grep "client max protocol"
        client max protocol = SMB3
ubuntu@artful-desktop:~$ smbtree
ubuntu@artful-desktop:~$ 


So in summay, bionic samba's own tools seem to know when NT1 is needed and 
downgrade appropriately. Ideally the rest of the smb ecosystem should do the 
same, assuming there is no way to get the computer listing with non-NT1 
protocols.

-- 
You received this bug notification because you are a member of Ubuntu
Server, which is subscribed to samba in Ubuntu.
https://bugs.launchpad.net/bugs/1767454

Title:
  "Other Locations" does not automatically find Samba servers in Ubuntu
  18.04

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https://bugs.launchpad.net/gvfs/+bug/1767454/+subscriptions

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