TOPS-20 Telnet and Port Forwading issue

Hi folks, I don't know if this is the best place to ask this question, but I don't know of any better forums for PDP-10 discussion, so hopefully it's on-topic enough. I recently set up the KLH10 PDP-10 emulator on my network, running TOPS-20 7.1. It's on a box in my 192.168.1.0/24 network. TCP/IP works great, I can telnet to it from within my network without any issue. I also set up my firewall (a box running CentOS 7.1) to port forward Interestingly, when I telnet from _outside_ the network to my firewall's port 2320, it works, but Telnet goes into line mode rather than character mode! I can fix it with telnet escape (^]) by setting character mode explicitly with "mode character", but that's kind of annoying to do each time I connect. It feels like Telnet is no longer doing line mode / character mode negotiation when I'm port forwarding. It's most mysterious. If you want to see for yourself, you can telnet to gatekeeper.retronet.net 2320, which is the KLH10 instance. Does this ring any bells for anyone? -Seth -- Seth Morabito seth at loomcom.com