Hi,

I'm running Sernet Samba 4.4.5 in a CTDB clustered fileserver setup, NT style domain. At random dates (it's usually noticed in the morning as users log in), users can suddenly not connect to network shares.

Attempting to make an authenticated connection to the fileservers (either via CTDB IP or direct) using "smbclient -L" or "smbclient //server/share" also fails with NT_STATUS_INVALID_PARAMETER. smbclient -L strangely works fine as guest.

Domain Controllers are all Centos 6 with either Sernet Samba 3.6.22 or 3.6.25.

Logs on the file servers show many instances of these lines:

/var/log/samba/172.17.44.83:  ntlmssp_server_postauth: invalid NTLMSSP_MIC for user=[foo] domain=[DOM] workstation=[DK-L]
/var/log/samba/172.17.44.83:[2016/09/29 09:54:35.158127,  1] ../auth/ntlmssp/ntlmssp_server.c:950(ntlmssp_server_postauth)
/var/log/samba/172.17.44.83:  ntlmssp_server_postauth: invalid NTLMSSP_MIC for user=[foo] domain=[DOM] workstation=[DK-L]
/var/log/samba/172.17.51.57:[2016/09/19 10:38:27.684713,  1] ../auth/ntlmssp/ntlmssp_server.c:948(ntlmssp_server_postauth)
/var/log/samba/172.17.51.57:  ntlmssp_server_postauth: invalid NTLMSSP_MIC for user=[DK-E$] domain=[DOM] workstation=[DK-E]
/var/log/samba/172.17.51.57:[2016/09/19 10:38:27.754462,  1] ../auth/ntlmssp/ntlmssp_server.c:948(ntlmssp_server_postauth)
/var/log/samba/172.17.51.57:  ntlmssp_server_postauth: invalid NTLMSSP_MIC for user=[DK-E$] domain=[DOM] workstation=[DK-E]

I don't believe this to be CTDB related as another Samba user has reported this in a non-CTDB setup. He also runs 4.4.x file servers with 3.6.x DCs.