A5000 - diving in at the deep end!

[rubber_jonnie]

So, this little widget arrived over the weekend:

PXL_20231204_135114619.jpg

It's jokingly called the 'Throwing Star LAN TAP', but let me tell you, the damn thing works. There are two ports that are straight through for your connection, the other two allow you to tap either inbound or outbound traffic.

For £10 and 10 minutes to build, it is really quite impressive and more than good enough to capture the 10Mbit Half Duplex traffic to the A5000.

And what does this prove you ask? Well I can now effectively tap between the switch and the A5000, the last hop, and I can see that the response from the Windows machine (The SYN,ACK) does indeed get to the A5000. Very useful little tool, that's for sure.

So what next?

Well I know that I can set up a telnet server (Igor) on the A5000 and connect just fine on different ports depending on what I set Igor up to use. TCP is as far as I can tell, just fine, at least based on the telnet setup.

So why then is the SYN,ACK from the Windows server ignored?

So, a little digging and I have found Wiresalmon, which is packet capture for RiscOS, so I'm going to try it.

It's way less sophisticated than Wiresahrk, but it may at least let me see what the A5000 is doing now that I know the SYN,ACK is actually arriving.

More to follow when I get a chance to play with Wiresalmon.

[stephen_usher]

It's probably the SMB client that's buggy or only supports an ancient version of the protocol which they reverse engineered and it doesn't work with "modern" SMBv1 servers, or something.

Have you thought about other ways to get the data on/off the machine, such as an FTP daemon running on the Acorn and accessed via Windows file Explorer?

[rubber_jonnie]

It's probably the SMB client that's buggy or only supports an ancient version of the protocol which they reverse engineered and it doesn't work with "modern" SMBv1 servers, or something.

Have you thought about other ways to get the data on/off the machine, such as an FTP daemon running on the Acorn and accessed via Windows file Explorer?

The problem is, it isn't getting that far, the 3 way handshake fails so it's not SMB at the point it fails. It's supposed to work with Windows 10 and below.

I have tried setting up a Samba server on the A5000, and it gives a 'not enough memory' error. I haven't yet tried an FTP server, but the !FTPc client I have is asking for more modules, or if I try an older version, it's not even leaving the A5000.

I'm still looking for alternatives that will work on the A5000, and found one, but the files seem to be bad and they won't even copy to floppy. :( As for Wiresalmon, turns out it requires RiscOS 3.5, so that's a no go.

Since Telnet works when the server is running on the A5000, it is logical to find some sort of file sharing server that works on the A5000 seeing as that direction seems to work normally.

It seems like the A5000 and Windows devices agree on some element in the reply from the windows server, so something like window size or one of the other TCP flags is upsetting the A5000 due to it's older stack.

More digging required.

[stephen_usher]

To get the TCP handshake the stack has to have something listening on that port. Sounds like that's the part that's broken.

[rubber_jonnie]

To get the TCP handshake the stack has to have something listening on that port. Sounds like that's the part that's broken.

The A5000 is initiating on port 1025 IIRC, and the Windows server is replying to the port the A5000 made the connection on, I can see that in my packet captures.

For Telnet, where the connection is initiated elsewhere, the A5000 is fine with it.

What I can't easily tell is if the port is closed or blocked for the return traffic, but the SYN,ACK is coming back on the correct port.

Directionality definitely seems to play a part.

[rubber_jonnie]

OK, so some movement here. I have Sunfish (NFS client) and Moonfish(NFS server) working on the A5000.

When I try to connect to the NFS server from my Windows server, it fails, but there is a proper conversation happening. I need to tinker with it some more but it is looking positive.

I need to see if I can use Sunfish to connect to a machine running NFS, see how it looks the other way.

[HigashiJun]

The quest goes on !

[rubber_jonnie]

The quest goes on !

I feel the destination may be closer though :)

[HigashiJun]

I feel the destination may be closer though :)

That would be great !

[rubber_jonnie]

I feel the destination may be closer though :)

That would be great !

I just got NFS working on my Windows 2016 server with anonymous access, and my Mac can see it, so I will try connecting from the A5000 tomorrow, and also now I know what to look for from the Mac I will see if I can connect to an NFS share on the A5000.

:)