samba - Dec 2016 - Fed 25: Samba suddenly refuses all XP connections, Win 7 OK

I have several XP VM's and its also physically one on a on a multiboot 
laptop. Just today, they all gave "unknown username or bad password"
to
the main samba server which has been working fine for years. There is 
nothing wrong with the accounts because Win 7 clients using the same 
credentials are fine. On the LAN I also have Ubuntu servers and their 
samba shares are OK from XP. It seems its just the specific combination 
of XP client to Fedora samba which has this problem. I even downgraded 
samba from the current 4.5.1 to 4.5.0 but it still shows this issue. The 
Ubuntu version which is OK is 4.3.11

Also note when I browse the LAN from the broken XP clients in Explorer 
the server name comes up, so XP does know it is there. When I click the 
server name I'm asked to login, and can't as described. Normally these 
are permanently mapped to drive letters so I never even see the prompt.

Could something else have changed which causes this, like some kind of 
password encryption which XP can't handle, etc? I'm pretty sure some 
update during my regular "DNF update" runs did it, only because thats 
about all I was doing in the run up to discovering this issue. Thanks.

Carl Whalley via samba <samba at lists.samba.org>
writes:
> Could something else have changed which causes this, like some kind of 
> password encryption which XP can't handle, etc? I'm pretty sure
some
> update during my regular "DNF update" runs did it, only because
thats
> about all I was doing in the run up to discovering this issue. Thanks.
Samba has client signing on by default since the badlock fixes. The
quick *insecure* fix is to stick this in your smb.conf (global)

  client ipc signing = auto

Depending on which samba version you have now you might want to try this
to:

  ntlm auth = yes

More info on:
- http://badlock.org
- https://www.samba.org/samba/security/CVE-2016-2115.html

-- 
Aurélien Aptel / SUSE Labs Samba Team
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