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Cross domain authentication

I have a pc, joined to domain A
On this pc I have a network share, on a file server on domain B

(on domain B I have group policy enable > after 10 wrong pwd tries, lock user)

I don't understand why, at startup, the pc tries to authenticate on that network drive but it fails (different domain/pwd)

Funny thing, I've also removed the network mapped drive, but even if I \\fileserver, the pc tries to authenticate: it fails again (no pop up for credentials appear) and the user, on domain B is locked

The 2 domain, A & B, are not in trust.
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Steven Wells
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What event is logged in the security log of re server hosting the share?

Have you rebooted and cleared the saved usernames and passwords from the client computer?

You should be able to authenticate across the share as long as the computer isn't trying to use any other credential first
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09/24 08:13:17 [LOGON] domainB: SamLogon: Network logon of domainA\pippo from WKS007 Entered
09/24 08:13:17 [LOGON] domainB: NlPickDomainWithAccount: domainA\pippo: Algorithm entered. UPN:0 Sam:1 Exp:0 Cross: 0 Root:1 DC:0
09/24 08:13:18 [LOGON] domainB: SamLogon: Network logon of domainA\pippo from WKS007 Returns 0xC000006A

This is what I see from netlogon on DC on domain B
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Yes, in theory I removed mapped network drive and rebooted: no credential should be stored
You could try creating a user account on both networks with the same name and passord

Are you using ntlm authentication on the destination domain?

I would look at the authentication method on the share domain. If Kerberos is being used the client may not be able to authencate.
You will also need to specifify domainb\user from the client on domain a if that makes sense.
yes, the user, with the same pwd, exist in both domains

I don't think the problem is the auth method: in the same config, I have 9 users working, 1 not

Any other ideas?
Thx
If one user is not working perhaps look at that account. 0xC000006A Refers to unknown error or wrong password.
still in trouble... any other suggestions?
Is it doing the behavior no matter what user account you logon with on that same machine?

ie, is there something in the profile of that user account doing the mapping, and therefore, the locking?

It sounds like a process or something else is actually doing the connection.

You could use process monitor to monitor the network traffic to see what actually is creating the connection, and then work backwards.   It sounds like a credential manager issue ie, stored usernames and passwords.

If it's related to one profile only, perhaps re-create that profile.
the problem happens to random users, from different machines

no mapping, removed all

when I start the pc (nothing mapped) all is ok
when I just write in file Explorer \\filserver, the pc start authentication trough domain, and user get locked
Confirm you have checked the credential manger on the clients machines?

Could you perhaps look at guest access to the share, rather than user authentication? ( enable guest account )
Are all machines using the same user account?
no pwd stored in the machine

no guest account > strange thing the user worked for several months, and that the issue started
no different machines/accounts
You mention that you don't get promoted for credentials. The account just gets locked. I am inclined to think the accounts are being locked out by something on the server domain outside the domain that is connecting in.

I would recommend downloading a lockout examiner product -even just eval- and scan the domain that has the server share to try and work out where the account is being locked out. Or there should be a number of attempts before the account locks. I would we expect the account is being locked out somewhere else.
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The log just shows the fact the account was locked. It doesn't show where or how. You need to examine the security log on the DC too. The tool may also require changes to the auditing policy too. I can recommend the netrix product for this. It has helped me lots of times.
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