Another anon, not the OP, here.

I don't usually trust support people (not front line anyway). I usually trust Wireshark (but I don't claim to understand what it tells me).

Here's what Wireshark says, on Plusnet, when I do the telnet to port 22, wait a few seconds, then close the DOS box. Ignore the missing packets, they're from an unrelated activity and I was too lazy to get Wireshark to filter them. Does it tell anybody anything?


1 0.000000 192.168.0.101 212.243.7.194 TCP argis-te > ssh [SYN] Seq=0 Win=65535 Len=0 MSS=1460
2 0.047031 212.243.7.194 192.168.0.101 TCP ssh > argis-te [SYN, ACK] Seq=0 Ack=1 Win=16384 Len=0 MSS=1400 WS=0WS=1
3 0.047077 192.168.0.101 212.243.7.194 TCP argis-te > ssh [ACK] Seq=1 Ack=1 Win=129940 Len=0
35 10.956560 192.168.0.101 212.243.7.194 TCP argis-te > ssh [FIN, ACK] Seq=1 Ack=1 Win=129940 Len=0
36 11.006143 212.243.7.194 192.168.0.101 TCP ssh > argis-te [ACK] Seq=1 Ack=2 Win=65535 Len=0
37 11.006219 212.243.7.194 192.168.0.101 TCP ssh > argis-te [FIN, ACK] Seq=1 Ack=2 Win=65535 Len=0
38 11.006238 192.168.0.101 212.243.7.194 TCP argis-te > ssh [ACK] Seq=2 Ack=2 Win=129940 Len=0

Original poster here.

I bet you have all been dying to know what happened

I have assumed that when you place a computer in a DMZ, then all ports and protocols are open / allowed, (makes sense to me...).
Alas my BT / 2 Wire 1801HG has a separate page where you can allow listed protocols, which still applies in the DMZ !
I have always had Telnet and FTP open, but it wasn't until I ticked the
"Allow all other protocols" box that I could telnet & connect to the Across server (but not get a reply, it's encrypted).
Ofcourse the agency had problem with that server at the same time, so it didn't get resolved until couple of weeks ago.
Never did find out what protocol is actually used !

Thanks to all who tried to help.
Regards,
Martin