Created attachment 10367 [details]
My smb.conf

Hi.

It looks like nmbd cripples netbios name is too long and needs to be truncate.

[global]
	netbios name = Xabcdefghijklmnopqrstuvwxyz

Logs:

(most interesting are parts with:
Oct 24 07:10:20 unused-4-106 nmbd[20240]: register_name: NetBIOS name XABCDEFGHIJKLMNOPQRSTUVWXYZ is too long. Truncating to (yes here is nothing)
Oct 24 07:10:43 unused-4-106 nmbd[20240]: Samba name server XABCDEFGHIJKLMNOPQRSTUVWXYZ is now a local master browser for workgroup APPLEGROUP on subnet 192.168.254.76


Oct 24 07:10:20 unused-4-106 nmbd[20239]: [2014/10/24 07:10:20.840695,  0, pid=20239, effective(0, 0), real(0, 0)] ../source3/nmbd/nmbd.c:945(main)
Oct 24 07:10:20 unused-4-106 nmbd[20239]: standard input is not a socket, assuming -D option
Oct 24 07:10:20 unused-4-106 nmbd[20240]: [2014/10/24 07:10:20.845337,  0, pid=20240, effective(0, 0), real(0, 0)] ../source3/nmbd/nmbd_nameregister.c:492(register_name)
Oct 24 07:10:20 unused-4-106 nmbd[20240]: register_name: NetBIOS name XABCDEFGHIJKLMNOPQRSTUVWXYZ is too long. Truncating to
Oct 24 07:10:20 unused-4-106 nmbd[20240]: [2014/10/24 07:10:20.845485,  0, pid=20240, effective(0, 0), real(0, 0)] ../source3/nmbd/nmbd_nameregister.c:492(register_name)
Oct 24 07:10:20 unused-4-106 nmbd[20240]: register_name: NetBIOS name XABCDEFGHIJKLMNOPQRSTUVWXYZ is too long. Truncating to
Oct 24 07:10:20 unused-4-106 nmbd[20240]: [2014/10/24 07:10:20.845623,  0, pid=20240, effective(0, 0), real(0, 0)] ../source3/nmbd/nmbd_nameregister.c:492(register_name)
Oct 24 07:10:20 unused-4-106 nmbd[20240]: register_name: NetBIOS name XABCDEFGHIJKLMNOPQRSTUVWXYZ is too long. Truncating to
Oct 24 07:10:20 unused-4-106 nmbd[20240]: [2014/10/24 07:10:20.846109,  0, pid=20240, effective(0, 0), real(0, 0)] ../source3/nmbd/nmbd_nameregister.c:492(register_name)
Oct 24 07:10:20 unused-4-106 nmbd[20240]: register_name: NetBIOS name XABCDEFGHIJKLMNOPQRSTUVWXYZ is too long. Truncating to
Oct 24 07:10:20 unused-4-106 nmbd[20240]: [2014/10/24 07:10:20.846220,  0, pid=20240, effective(0, 0), real(0, 0)] ../source3/nmbd/nmbd_nameregister.c:492(register_name)
Oct 24 07:10:20 unused-4-106 nmbd[20240]: register_name: NetBIOS name XABCDEFGHIJKLMNOPQRSTUVWXYZ is too long. Truncating to
Oct 24 07:10:20 unused-4-106 nmbd[20240]: [2014/10/24 07:10:20.846333,  0, pid=20240, effective(0, 0), real(0, 0)] ../source3/nmbd/nmbd_nameregister.c:492(register_name)
Oct 24 07:10:20 unused-4-106 nmbd[20240]: register_name: NetBIOS name XABCDEFGHIJKLMNOPQRSTUVWXYZ is too long. Truncating to
Oct 24 07:10:20 unused-4-106 nmbd[20240]: [2014/10/24 07:10:20.849986,  0, pid=20240, effective(0, 0), real(0, 0)] ../lib/util/become_daemon.c:136(daemon_ready)
Oct 24 07:10:20 unused-4-106 nmbd[20240]: STATUS=daemon 'nmbd' finished starting up and ready to serve connectionsread_udp_v4_socket: ip 192.168.254.76 port 35072 read: 68
Oct 24 07:10:20 unused-4-106 systemd: Started Samba NMB Daemon.
Oct 24 07:10:43 unused-4-106 nmbd[20240]: [2014/10/24 07:10:43.934065,  0, pid=20240, effective(0, 0), real(0, 0)] ../source3/nmbd/nmbd_become_lmb.c:397(become_local_master_stage2)
Oct 24 07:10:43 unused-4-106 nmbd[20240]: *****
Oct 24 07:10:43 unused-4-106 nmbd[20240]: 
Oct 24 07:10:43 unused-4-106 nmbd[20240]: Samba name server XABCDEFGHIJKLMNOPQRSTUVWXYZ is now a local master browser for workgroup APPLEGROUP on subnet 192.168.254.76
Oct 24 07:10:43 unused-4-106 nmbd[20240]: 
Oct 24 07:10:43 unused-4-106 nmbd[20240]: *****
Oct 24 07:10:43 unused-4-106 nmbd[20240]: [2014/10/24 07:10:43.935006,  0, pid=20240, effective(0, 0), real(0, 0)] ../source3/nmbd/nmbd_become_lmb.c:397(become_local_master_stage2)
Oct 24 07:10:43 unused-4-106 nmbd[20240]: *****
Oct 24 07:10:43 unused-4-106 nmbd[20240]: 
Oct 24 07:10:43 unused-4-106 nmbd[20240]: Samba name server XABCDEFGHIJKLMNOPQRSTUVWXYZ is now a local master browser for workgroup APPLEGROUP on subnet 10.34.4.106
Oct 24 07:10:43 unused-4-106 nmbd[20240]: 
Oct 24 07:10:43 unused-4-106 nmbd[20240]: *****

Analyse:
source3/nmbd/nmbd_nameregister.c:

# gdb --args nmbd -F -d 10 -S
(gdb) break register_name
(gdb) run

    477 void register_name(struct subnet_record *subrec,
    478                    const char *name, int type, uint16 nb_flags,
    479                    register_name_success_function success_fn,
    480                    register_name_fail_function fail_fn,
    481                    struct userdata_struct *userdata)
    482 {
    483         struct nmb_name nmbname;
    484         nstring nname;
    485 
    486         errno = 0;
    487         push_ascii_nstring(nname, name);

(gdb) print nname
$1 = "\000ABCDEFGHIJKLMNO"
(gdb) print name
$2 = 0x55555579bdf0 "XABCDEFGHIJKLMNOPQRSTUVWXYZ"

... errno is E2BIG ...

    488         if (errno == E2BIG) {
    489                 unstring tname;
    490                 pull_ascii_nstring(tname, sizeof(tname), nname);

(gdb) print nname
$4 = "\000ABCDEFGHIJKLMNO"
(gdb) print tname
$5 = "\000\000\000\000\000\000\000\000\373\254\242\364\377\177\000\000L\000\000\000UU\000\000\220\234yUUU\000\000\220\234yUUU\000\000\000HE\250\362\277\230:\220\234yUUU\000\000\060\356yUUU\000"

    491                 DEBUG(0,("register_name: NetBIOS name %s is too long. Truncating to %s\n",
    492                         name, tname));
    493                 make_nmb_name(&nmbname, tname, type);

(gdb) print nmbname
$7 = {name = '\000' <repeats 15 times>, scope = '\000' <repeats 63 times>, name_type = 32}

    494         } else {
    495                 make_nmb_name(&nmbname, name, type);
    496         }