exxos's Atari, Amiga & retro forum

HigashiJun wrote: 24 Nov 2023 12:29 As you wrote, it's really odd.

Has somebody managed to connect his machine on Stardot forum ?

They have, but I need to go back and re-read it.

That all looks to check out, at least from the routing side.

stephen_usher wrote: 24 Nov 2023 15:22 That all looks to check out, at least from the routing side.

Indeed it does. I've just changed the cable but no different, and the old cable checks out fine with my cable tester.

Bit of a head scratcher, but I've ordered a small tap to go between the A5000 and the switch, when it comes I can capture right up to the NIC. If I see the SYN/ACK there then it's something inside the machine, either hardware or software.

Of course if a TCP conversation can't be started, then all bets are off.

If feels like a TCP/IP stack issue if ICMP is working.

stephen_usher wrote: 24 Nov 2023 16:36 If feels like a TCP/IP stack issue if ICMP is working.

Yeah, most odd, and more than a bit annoying.

I can try some more with the CJE stack as I can easily switch !boot files around.

I found some detail on RISCOS TCP commands here: RISCOS TCP Commands and have been doing some testing.

If I run a traceroute to dns.google, it happly resolves the address (Googles DNS servers are set in the TCP/IP configuration for the A5000) and it traces just fine:


I also did a capture via a mirrored port on the switch when doing the traceroute and it looked the same as from my laptop. So ICMP works fine, DNS works fine (dns.google isn't in my hosts file, but is one of my DNS servers) and apparently UDP works fine.

However. looking at the showstat command, I see this:


What's interesting is the Polarity, which is shows as 'Incorrect' and I'm wondering if this is an issue, since the example shown on the webpage shows the value of 'Correct'.

I'm going to have a look at the pong command next, as it allows for a choice of connection types, so UDP or TCP, and I'll see what Wireshark shows me

If DNS is working then so is UDP/IP and routing otherwise the UDP packets wouldn't be able to get out to Google and the replies come back. So, your layer 1, 2, 3, 3 and 5 are OK, it's the TCP transport and sockets which look to be broken.

stephen_usher wrote: 26 Nov 2023 16:06 If DNS is working then so is UDP/IP and routing otherwise the UDP packets wouldn't be able to get out to Google and the replies come back. So, your layer 1, 2, 3, 3 and 5 are OK, it's the TCP transport and sockets which look to be broken.

It certainly looks that way, yes. I have a LAN TAP kit coming, so I can fit that immediately between the A5000 and the cable. I expect it'll show that the SYN, ACK packet coming back from the Windows laptop is arriving at the NIC, but is never seen by the A5000.

The question is, if it is the TCP side of things that's failing, how on earth do I fix it?

I am going to try the CJE boot again as I never tried LanMan98 with it, so you never know, but it does seem rather odd that the SYN is sent and arrives at the Windows machine, but the SYN, ACK never seems to arrive.

Something in the TCP stack is working, but it just never sees the response from the windows machine then resets the connection. The ports and directionality are all matching at the A5000. It almost seems that there is a firewall blocking it.

Wish I could do a packet capture on the A5000.

Isn't your CENTRECOM 210T stuff broken ?

:?:

HigashiJun wrote: 27 Nov 2023 09:21 Isn't your CENTRECOM 210T stuff broken ?

:?:

No, that didn't work because the jumpers were set to use the BNC connector. BNC or AUI, I get exactly the same issue. Also, I tested the Centrecom on another device and it worked perfectly, at least as far as I could tell. I may double check it, but they are pretty reliable, and the fact that the problem is the same even with the BNC connector suggests its a software issue.

I should have a LAN TAP soon, I can place that between the cable and the A5000 to see if the SYN/ACK from the Windows server gets to the A5000. I suspect it is as I see it at the mirror port on the switch, but the TAP will be as close to the A5000 as I can get.