Am 20.03.20 um 11:19 schrieb Stefan Metzmacher: > Hi, > > I recently noticed the following problem with a 4.15 Kernel > on Linux Mint: > > /etc/fstab has something like this: > >> //172.31.9.132/share1 /media/cifs/share1 cifs vers=1.0,credentials=/media/cifs/cifsmount.creds.txt 0 1 >> //172.31.9.132/share2 /media/cifs/share2 cifs vers=1.0,credentials=/media/cifs/cifsmount.creds.txt 0 1 >> //172.31.9.132/share3 /media/cifs/share3 cifs vers=1.0,credentials=/media/cifs/cifsmount.creds.txt 0 1 >> //172.31.9.132/share4 /media/cifs/share4 cifs vers=1.0,credentials=/media/cifs/cifsmount.creds.txt 0 1 > > 172.31.9.132 is a Windows Server in a Domain with Samba AD-DCs. > > The initial mounting works fine, but after some time Samba > logs WRONG_PASSWORD and finally ACCOUNT_LOCKED_OUT. > > From various clients this happens about once per hour! > > In order to debug this I extended wireshark. > wireshark was already able to decrypt NTLMSSP encryption > when an NTLMSSP password and/or a keytab is provided. > I extended that in order add some useful expert info > that shows which NTHASH was used for a given authentication. > That is also available with an Schannel encrypted Netr_LogonSamLogon* > call. This landed in wiresharks master branch a few days ago. > > The customers capture didn't show that information, > which meant that the client used a wrong password > when it got LOGON_FAILURE from the Windows fileserver > (because that got WRONG_PASSWORD or ACCOUNT_LOCKED_OUT > from the AD-DC). > > I cross checked that with smbclient and there wireshark > showed the correct password was used. > > This is very strange and I had the idea to just check > if maybe an empty string password was used by the client. > So I created a keytab with the NTHASH of an empty string. > And wireshark showed that this NTHASH was actually used... > > Has anybody seen this before? We'll retry this with a newer > kernel next week... I was able to capture that in more detail and it's actually not a problem with cifs.ko. The dialects in the SMB Negprot request contain "Samba", so the problem is triggered by some [lib]smbclient user, maybe it's gvfs related. I hope to find more in the next days. The bahavior was seen with Samba 4.3.* and 4.7.* where 4.7 sends an empty NTLM response instead of using the nthash of an empty string. metze
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