What would cause a RST,ACK from client to SMB server?
Hi, I'm trying to troubleshoot a problem I have with a Windows PC connecting to an Synology DS218J NAS on SMB2. I keep getting errors whether connecting via hostname or IP address directly, even when Windows Defender firewall is disabled. The NAS server is working fine as I can access its web portal from the same PC, and I can also access the SMB file shares with other mobile devices/laptops. I've tried looking at the SMB version settings (SMB2 is enabled on the NAS), and even did a Network Reset on the PC, but still no go, so I decided to delve deeper by looking at a packet capture.
What I see when I try to connect to the NAS on Windows Explorer, is the following:
- TCP 3-way handshake ([SYN],[SYN,ACK],[ACK])
- Negotiate Protocol Request from PC to NAS
- TCP ACK from NAS to PC
- Negotiate Protocol Response from NAS to PC
- [RST,ACK] from PC to NAS
Steps 1-5 will then repeat twice (total 3x) before ultimately failing.
What could be wrong here? Is it a TCP problem, an SMB problem or some other problem?
Attached screenshot of the negotiate protocol response from the server.
A (reasonable) guess would be that the PC doesn't like the Negotiate Protocol Response. Sharing a capture with that packet would be very helpful. What OS is the PC running?
Here it is in the original post. Let me know if you want to expand anything. Not sure what I should be looking at.
You've shown us a screenshot of the RST, ACK which is the client closing the connection. What we really need to see id the SMB Negotiation in a format that allows inspection, i.e. a Wireshark capture.
Please share the capture using a public share such as Goggle Drive, DropBox etc. and post a link to it back here.
Hi, here's the link I notice from comparing a working and non working capture, that the working one has some NTLM information in the Negotiate protocol request, while the non working one (which is the link above) doesn't have. Not sure of the significance.
I think you'll have to wait for an SMB expert to take a look. The response looks OK to me, albeit only version SMB 2.0.2, so an older version, but the client does say that's supported in its request.
Is it an auth issue? Are you sure the username\password for the account is correct for this PC?
Does the NAS support SMB3?
@grahamb I'm not even accessing the shared folders, only the NAS at \hostname, so it shouldn't be an auth problem? @bubbasnmp it does not I didn't enable it, why?
You might poke around on the Synology forum to see if some combination of Windows 10 and NAS settings fixes this.
I've tried Synology, Windows 10, Microsoft and Anandtech forums, so far nobody has an answer, hence I'm delving into Wireshark packet captures lol. Short of nuking Windows and reinstalling it I don't have any other ideas.