Samba file locking

samba

I'd like to set up my samba server in the following way:

Client 1 opens file A
Client 2 attempts to open file A while Client 1 has it open
Client 2 is granted read-only access to the file

Edit: All clients will be Windows XP or Windows 7 machines.

As per this page, what I want would be closest to a deny-mode of DENY_DOS, but I can't seem to make that option take effect.

Any help would be greatly appreciated.

Best Answer

You cannot force all programs to use the file locking mechanism provided by samba. A lot of 'simple' applications just open the file, make a local copy (either in memory or on local disk) and then close the original file, so the lock only lasts as long as the opening and copying action. Notepad is one example of this. Moreover, this is actually a feature of most progams, not a shortcoming.

Think about what happens when an applications crashes with the lock still in place. Programs using filesystem locks should be aware of it and its implications and have a recover and release mechanism. That's why 'simple' applications avoid filesystem locking.

If you really want to use some kind of 'in use' messages for all applications you should use a versioning system. As mentioned elsewhere on serverfault, this isn't necessarily a technical problem, more a social one: you'll have a hard time convincing non-technical people to actually use it.

Related Solutions

Samba Permissions – I’m going to throw it!

This might help. I do something similar, but only one share is open to the group's users. Other shares are read-only except for a single maintainer user. The [global] section of my smb.conf is almost identical to yours, except I don't use the force create/directory mode directives (in my case, they'd interfere with the other shares).

Here's the share definition:

[shared stuff]
        comment = blah, blah, etc
        path = /path/to/share
        write list = @sambagroup
        force group = +sambagroup
        read only = yes
        directory mask = 0775
        create mask = 0664
        guest ok = yes
        invalid users = root
        case sensitive = True
        default case = lower
        preserve case = yes
        short preserve case = yes

The important stuff here are these:

read only = yes -- by default, read only.
guest ok = yes -- guests can browse.
write list = @sambagroup -- Authenticated members of sambagroup can write.
force group = +sambagroup -- The + means that the force only applies to existing members of sambagroup. They're already the only ones who can write. I think, without the +, guest is given sambagroup credentials, which is not wanted (particularly with the write list directive above).
directory mask = 0775
create mask = 0664

These do exactly what you want yours to do: "drwxrwxr-x" on directories, "rwxrwxr-x" on files, and newly created files are owned by the user and sambagroup. The maintainers of the other shares get the same permissions as everyone else when working in shared stuff, and permissions & groups are normal when they work in the other shares.

My smb.conf has been working with only minor tweaks through several different versions of Samba, and currently is used with Samba 3.2.5. I never had it running on Ubuntu 8.04, but it ran on Ubuntu 7.04 for a long time before getting migrated to a recent Debian Lenny install.

Samba – Windows/Samba connection error

[Can't seem to add comment, so am creating a new answer]

Erk. Changing the port to TCP 139 is a fudge. All this is doing is forcing the client to use legacy NetBIOS over TCP/IP (NBT), as opposed to pucker SMB running on TCP 445. Like Dave suggests, check the version of Samba running, and update if poss. Also, check you Windows version on the DC, as Win2k8 R2+ (and possibly R1) require SMB signing by default. This can be turned off, but again, it's another fudge.

Best Answer

Related Solutions

Samba Permissions – I’m going to throw it!

Samba – Windows/Samba connection error

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