[Samba] [Samba-it] samba 4.x: centos 7: Bad SMB2 signature for message

[Dario Lesca]

Hi, in a network with a PDC Linux 3.6.x, I have join to domain a
Centos7.1 with samba 4.1.12 (last version from  official repository).

All work fine, but after some days the connection to the share folder
not work anymore for the user with Win8 and Win8.1.
Into log I see this messages:

> Sep 16 09:56:14 s-backup smbd[21878]: STATUS=daemon 'smbd' finished starting up and ready to serve connectionsBad SMB2 signature for message
> Sep 16 09:56:14 s-backup smbd[21878]: [2015/09/16 09:56:14.379103,  0] ../lib/util/util.c:556(dump_data)
> Sep 16 09:56:14 s-backup smbd[21878]: [0000] 55 FA FB 06 1F F9 B1 C9   27 44 09 C3 16 E1 CF 13   U....... 'D......
> Sep 16 09:56:14 s-backup smbd[21878]: [2015/09/16 09:56:14.379252,  0] ../lib/util/util.c:556(dump_data)
> Sep 16 09:56:14 s-backup smbd[21878]: [0000] DF EA AC A9 66 40 6C 8F   7A A0 D5 D1 45 CA 44 36   ....f at l. z...E.D6
> Sep 16 09:56:14 s-backup smbd[21879]: STATUS=daemon 'smbd' finished starting up and ready to serve connectionsBad SMB2 signature for message
> Sep 16 09:56:14 s-backup smbd[21879]: [2015/09/16 09:56:14.468575,  0] ../lib/util/util.c:556(dump_data)
> Sep 16 09:56:14 s-backup smbd[21879]: [0000] 8D 90 BE CD 16 B5 49 85   76 54 67 F3 6B 00 EE 35   ......I. vTg.k..5
> Sep 16 09:56:14 s-backup smbd[21879]: [2015/09/16 09:56:14.468720,  0] ../lib/util/util.c:556(dump_data)
> Sep 16 09:56:14 s-backup smbd[21879]: [0000] 6A 1D 77 98 7F 30 F0 19   25 9A 7E 22 EF 21 7E F4   j.w..0.. %.~".!~.
> Sep 16 09:56:23 s-backup smbd[21880]: STATUS=daemon 'smbd' finished starting up and ready to serve connectionsBad SMB2 signature for message
> Sep 16 09:56:23 s-backup smbd[21880]: [2015/09/16 09:56:23.810267,  0] ../lib/util/util.c:556(dump_data)
> Sep 16 09:56:23 s-backup smbd[21880]: [0000] 7E 31 21 53 92 62 4F 6D   F7 4B 69 DE B8 BB 87 E4   ~1!S.bOm .Ki.....
> Sep 16 09:56:23 s-backup smbd[21880]: [2015/09/16 09:56:23.810399,  0] ../lib/util/util.c:556(dump_data)
> Sep 16 09:56:23 s-backup smbd[21880]: [0000] A5 69 24 8B DE 9A 09 6E   5A D2 BE CB E5 F0 DD 48   .i$....n Z......H
> Sep 16 09:56:24 s-backup smbd[21880]: [2015/09/16 09:56:24.439693,  0] ../libcli/smb/smb2_signing.c:170(smb2_signing_check_pdu)
> Sep 16 09:56:24 s-backup smbd[21880]: Bad SMB2 signature for message
> Sep 16 09:56:24 s-backup smbd[21880]: [2015/09/16 09:56:24.439885,  0] ../lib/util/util.c:556(dump_data)
> Sep 16 09:56:24 s-backup smbd[21880]: [0000] 4D B5 57 BD B8 A3 1D CF   9C DC EE 21 39 CF FE 2E   M.W..... ...!9...
> Sep 16 09:56:24 s-backup smbd[21880]: [2015/09/16 09:56:24.440014,  0] ../lib/util/util.c:556(dump_data)
> Sep 16 09:56:24 s-backup smbd[21880]: [0000] 06 51 61 A1 72 99 53 48   FC F9 B4 9F 88 C9 E5 F6   .Qa.r.SH ........

Other PC with Win7 o WinXP work great, only Win8* do not connect.

If I restart samba:

    sudo systemctl restart smb nmb winbind

Win8* can connect again but after some day the problem happen again.

I believe it is a problem with SMB2/3 protocol, but I have try change
in various ways the 'server max protocol' options (now is set to SMB3)
without success.

> [root at s-backup ~]# testparm -s --parameter-name 'server max protocol'
> Load smb config files from /etc/samba/smb.conf
> rlimit_max: increasing rlimit_max (1024) to minimum Windows limit
> (16384)
> Processing section "[homes]"
> Processing section "[backup]"
> Processing section "[backup-aruba]"
> Loaded services file OK.
> SMB3

My smb.conf:

> [global]
>         workgroup = dominio
>         server string = Samba Server Version %v
>         log file = /var/log/samba/log.%m
>         max log size = 50
>         passdb backend = tdbsam:/etc/samba/account.tdb
>         security = domain
>         realm = s-backup.dominio.it
>    idmap config * : range = 1000000-9999999
>    idmap config * : backend = rid
>    winbind use default domain = yes
>    winbind enum users  = yes
>    winbind enum groups = yes
>    domain master = no
>    local master = no
>    store dos attributes = Yes
>         wins server = 192.168.50.1
>         load printers = no
>         cups options = raw
>         printcap name = /dev/null
>         printing = bsd
> [homes]
>         comment = Home Directories
>         browseable = no
>         writable = yes
> [backup]
>    comment = Cartella con Backup
>    path = /backup2t/rsnapshot
>    writable = no
>    public = yes
>    force user = root
>    force group = root
>    valid users = @DOMINIO\grpbackup


Someone have some suggest to permanently solve this problem?

Many Thanks for attention.

-- 
Dario Lesca
(inviato dal mio Linux Fedora 22 con Gnome 3.16)