[Samba] Semantics of "smb ports = 0"

[Nikolaus Rath]

Andrew Bartlett <abartlet at samba.org> writes:
> On Fri, 2012-04-27 at 10:56 -0400, Nikolaus Rath wrote:
>> On 04/26/2012 09:13 PM, Jeremy Allison wrote:
>> > On Wed, Apr 25, 2012 at 10:04:30AM -0400, Nikolaus Rath wrote:
>> >> Hello,
>> >>
>> >> The qemu emulator has a feature to fork a samba instance for file
>> >> sharing with the emulated hosts. It communicates with smbd over stdin.
>> >> The generated configuration file contains a "smb ports = 0" directive to
>> >> prevent smbd from listening to any ports.
>> >>
>> >> Unfortunately, with at least Samba 3.6.4 this causes a segfault
>> >> instead:
>> >>
>> >> [0] vostro:/tmp/qemu-smb.6836-0# smbd -i -s smb.conf
>> >> Unable to setup corepath for smbd: Operation not permitted
>> >> smbd version 3.6.4 started.
>> >> Copyright Andrew Tridgell and the Samba Team 1992-2011
>> >> open_sockets_smbd: No sockets available to bind to.
>> >> ===============================================================
>> >> Abnormal server exit: open_sockets_smbd() failed
>> >> ===============================================================
>> >> BACKTRACE: 6 stack frames:
>> >>  #0 smbd(log_stack_trace+0x1a) [0x7fe50c14f8ba]
>> >>  #1 smbd(+0x6a0743) [0x7fe50c3bd743]
>> >>  #2 smbd(+0x6a0a41) [0x7fe50c3bda41]
>> >>  #3 smbd(main+0xa52) [0x7fe50be26d42]
>> >>  #4 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xfd) [0x7fe508ac0ead]
>> >>  #5 smbd(+0x10a6b9) [0x7fe50be276b9]
>> >>
>> >>
>> >> Also, there is some confusion as to whether this option was actually
>> >> ever necessary.
>> >>
>> >> Could someone clarify if something like this is still needed, or if
>> >> Samba does the right think automatically? In the later case, has this
>> >> always been the case or was it introduced in a specific version (and the
>> >> "smb ports = 0" required before)?
>> > 
>> > In fack looking at the current code in v3-6-test, so long as
>> > you ensure that you run without the '-D' (deamonize) option,
>> > and fd 0 is a socket (we use getsockopt(fd, SOL_SOCKET, SO_TYPE...)
>> > to detect this) then we'll go into 'inetd' mode, which I
>> > think is what you want.
>> 
>> Yes. I am just wondering if this has always been the case, or if this is
>> a recent feature and smb ports = 0 may have been required in earlier
>> versions.
>
> This has always been the case.  This (inetd) mode of operation is the
> original mode of operation, well before we even had an smb.conf to put
> 'smb ports' into.  It remains supported, but isn't used much these days.

Great, thanks! I'll see if I can get this weird hack out of qemu then.


Best,

   -Nikolaus

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