[Samba] How to debug a hard freeze?

L.P.H. van Belle
Wed, 29 Dec 2021 13:39:09 -0000

Hai Valentijn,

Yeah, on 24e not many are behind there pc..

I had a quick look, and I dont see much wrong here..

But this device. : 192.168.103.42
What is that and what does it use to connect.
because, that looks to be the problem.


Now, you?re currenlty using an OpenLDAP backend,
Ubuntu notes in documentation that you should instead
integrate Samba with its own LDAP server in AD mode.

So my advice, setup samba AD and use its integrated ldap.

Greetz,

Louis



> -----Oorspronkelijk bericht-----
> Van: samba [mailto:samba-bounces at lists.samba.org] Namens
> Valentijn Sessink via samba
> Verzonden: woensdag 29 december 2021 13:50
> Aan: samba at lists.samba.org
> Onderwerp: [Samba] How to debug a hard freeze?
>
> Hello list,
>
> I'm having a hard freeze of samba once in a while, and I
> don't know how
> to debug it best. I hope this list can be of help - or should
> I ask my
> question on the devel list?
>
> See below for the issue I'm experiencing. I'm aware that December
24
> probably isn't the best day to send a message - I still had hoped for
> more than 0 replies ;-) (Sorry to repost - if that is considered
> unpolite, please feel free to tell me but please do so off-list).
>
> I know I could "strace" smbd and try to find which function
> stalls the
> thing, and I could also use wireshark; but I am afraid that this will
> get me tons and tons of traffic and logs - the problem
> manifests itself
> a couple of times per year and I don't have unlimited storage. Plus I
> don't know how to reproduce the problem properly, that is
> probably the
> biggest problem.
>
> Also, *if* I'm going to packetdump/log/strace everything, I'd
rather
> know the best way to proceed, i.e. instead of just maxing out on log
> level, know if there are better options.
>
> Any clues? Pointing in the right direction is also
> appreciated, I looked
> in the Samba-wiki but did not find anything; and using the info from
> "troubleshooting Samba", ch9 of a 22 year old O'Reilly book
> seems rather
> futile.
>
> Best regards,
>
> Valentijn
>
> -------- Forwarded Message --------
> Subject: smbd linux freeze, not responding to (TERM) signals
> Date: Fri, 24 Dec 2021 12:09:26 +0100
>
> Hi,
>
> For a couple of years now, my smbd hangs a couple of times
> per year: smb
> daemons do not respond to TERM signal, I have to use SIGKILL.
>
> This is in a small network with mostly Apple and a few Linux clients,
> server running Ubuntu Linux, used to be 18.04, now is 20.04.
>
> The users complain "I cannot connect to the server" and the
> only way to
> resolve is to restart smbd; however, the smbd daemons do not
> respond to
> TERM signals, I have to KILL them. ("systemctl restart
smbd.service"
> will wait for 90s, then kill all smbd-s).
>
> I'll try to give more information below, but I'm sure there
> is more to
> add - log level or anything. Suggestions welcome.
>
> Whenever the problem occurs, smbstatus shows several "(auth in
> progress)" lines and these SMBds specifically do not listen
> to any signals:
>
> Samba version 4.13.14-Ubuntu
> PID     Username     Group        Machine     Protocol Version
> Encryption           Signing
> --------------------------------------------------------------
> --------------------------------------------------------------
> ------------
> 1696515 (auth in progress)        192.168.103.42
> (ipv4:192.168.103.42:56390) SMB3_11           -                    -
> 1293711 userie       userie       192.168.102.119
> (ipv4:192.168.102.119:51048) SMB3_11           - partial(AES-128-CMAC)
> 4165094 userne       userne       192.168.102.153
> (ipv4:192.168.102.153:39456) SMB3_11           - partial(AES-128-CMAC)
> 259670  userne       userne       192.168.102.153
> (ipv4:192.168.102.153:39936) SMB3_11           - partial(AES-128-CMAC)
> 1700382 (auth in progress)        192.168.103.42
> (ipv4:192.168.103.42:56400) SMB3_11           -                    -
> 1711963 (auth in progress)        192.168.103.42
> (ipv4:192.168.103.42:53136) SMB3_11           -                    -
> 1708107 (auth in progress)        192.168.103.42
> (ipv4:192.168.103.42:53134) SMB3_11           -                    -
> 1700371 (auth in progress)        192.168.103.42
> (ipv4:192.168.103.42:56396) SMB3_11           -                    -
> 1657745 userlo       userlo       192.168.103.18
> (ipv4:192.168.103.18:53924) SMB3_11           - partial(AES-128-CMAC)
> 1696496 (auth in progress)        192.168.103.42
> (ipv4:192.168.103.42:56384) SMB3_11           -                    -
> 1696495 (auth in progress)        192.168.103.42
> (ipv4:192.168.103.42:56386) SMB3_11           -                    -
> 1696516 (auth in progress)        192.168.103.42
> (ipv4:192.168.103.42:56392) SMB3_11           -                    -
>
> Service      pid     Machine       Connected at Encryption   Signing
> --------------------------------------------------------------
> -------------------------------
> IPC$         1293711 192.168.102.119 vr dec 24 09:07:11 2021
> CET      -
>             -
> shar         1293711 192.168.102.119 vr dec 24 09:07:11 2021
> CET      -
>             -
> IPC$         1657745 192.168.103.18 vr dec 24 10:41:34 2021
> CET      -
>           -
> IPC$         1293711 192.168.102.119 vr dec 24 09:07:22 2021
> CET      -
>             -
> shar         1657745 192.168.103.18 vr dec 24 10:41:33 2021
> CET      -
>           -
> userie       1293711 192.168.102.119 vr dec 24 09:07:11 2021
> CET      -
>             -
> shar-shararaties 259670  192.168.102.153 do dec 23 10:37:13
> 2021 CET   -
>             -
> shar         4165094 192.168.102.153 do dec 23 09:23:24 2021
> CET      -
>             -
>
> No locked files
>
> In the above exampe, "kill 1696516" doesn't seem to do
> anything, 1696516
> stays where it is. However if I "kill -KILL" all pids that
> have "auth in
> progress" for status will make smbd behave correctly (Users:
> "yes, I can
> connect now").
>
> This situation used to be the same under Ubuntu 18.04 - but
> as that was
> a rather old smbd, I hoped to fix things with an upgrade. (Yes, I am
> aware of the fact that 4.13.14-Ubuntu is older, too.)
>
> The only difference from a more straight forward setup is
> probably that
> we run a separate LDAP server for authentication, with passdb
> backend  =
> ldapsam:ldap://127.0.0.1/
> Also, since this is an existing situation that went from upgrade to
> upgrade, I suspect that there will be a few outdated options
> in smb.conf:
>
> [global]
>          log level = 1
>          workgroup = shar
>          passdb backend  = ldapsam:ldap://127.0.0.1/
>          ldap admin dn   = cn=admin,dc=kantoor,dc=shar,dc=nl
>          ldap ssl        = off
>          ldap suffix     = dc=kantoor,dc=shar,dc=nl
>          ldap user suffix        = ou=Users
>          ldap group suffix       = ou=Groups
>          ldap machine suffix     = ou=Computers
>          unix extensions = yes
>          delete readonly = yes
>          ea support      = yes
>          ldap password sync      = yes
>          interfaces = 127.0.0.0/8 ens3
>          bind interfaces only = true
>          load printers = no
>          printing = bsd
>          printcap name = /dev/null
>          disable spoolss = Yes
>          disable netbios = yes
>          smb ports = 445
>          dns proxy = no
>          vfs objects = fruit streams_xattr
>          security = user
>
> Shares are pretty simple:
> [name]
>    force group = users
>    force directory mode    = 2770
>    force create mode       = 0660
>    directory mask  = 2770
>    create mode     = 0660
>    comment         = Comment
>    writable        = yes
>    path            = /home/somewhere
>    mangled names = no
>    mangling char = _
>    valid users = @users
>
>
> Oh, trying to find out what the daemon is doing:
> strace -p 1700382 (but maybe I'm totally mistaken here and
"strace"
> isn't the right tool):
> strace: Process 1700382 attached
> restart_syscall(<... resuming interrupted read ...>
>
>
> netstat shows:
> tcp        1      0 192.168.102.3:445       192.168.103.42:56400
> CLOSE_WAIT  1700382/smbd
> tcp        0      0 127.0.0.1:33010         127.0.0.1:389 ESTABLISHED
> 1700382/smbd
> unix  2      [ ]         DGRAM                    72953128
> 1700382/smbd
>          /var/lib/samba/private/msg.sock/1700382
>
> What could cause these hangs?
>
> Best regards,
>
> Valentijn
> --
> http://www.openoffice.nl/   Open Office - Linux Office Solutions
> Valentijn Sessink  v.sessink at openoffice.nl  +31(0)20-4214059
>
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