Daniel Lange's blog

Updating to irssi 0.8.19 (which is a mainly a bugfix release to 0.8.18) proved a real issue. The enter key (return key) stopped working. Ctrl-J still worked but that's way too annoying to remember after each line. Searching the github issues turned up #327 Numeric keypad "Enter" key stopped working which didn't help much. Digging deeper it shows the irssi devs enabled "App key" mode in these releases which causes so many issues, they had to implement a switch to turn it off again.

So a hopeful: /set term_appkey_mode off followed by Ctrl+J, remember ...

and ... nothing changed.

So finally, after more digging and a quick consideration to go back to irssi 0.8.17 on Debian stable (Jessie) ...

/bind ^M key return

Yes, irssi 0.8.19 wants to be told what the enter key is, like, by default. Duh.
No idea what caused this in my configuration, I've been using irssi for more than a decade so much cruft has accumulated in my .irssi/config but ... in case you run into this as well, hopefully I helped you save a morning for something better to do.

If you want to fumble this into your .irssi/config (e.g. because Ctrl-J does not work for you):

keyboard = (
  [...]
  { key = "^M"; id = "key"; data = "return"; },
  [...]
);

There is a add-on technology to X or VNC called NX by an Italian company called NoMachine. It's quite useful as it speeds up working on remote desktops via slow network connections (i.e. DSL pipes) substantially.

The libraries that implement NX are released under GPLv2 by that company. A server wrapping up the libraries' functionality is available as closed source from NoMachine or as a free product (GPLv2 again) by Fabian Franz, called FreeNX.

FreeNX itself is amazing as it is written in BASH (with a few helper functions in C). It's also able to mend some of the shortcomings of the NX architecture. E.g. stock NX requires a technical user called "nx" to able to ssh into the NX server with a public/private keypair. FreeNX can work around that for more secure set-ups.

One issue I bumped into quite regularly with Linux clients and Linux hosts from different distributions/localisations is that the keymaps are not compatible. This usually results in the ALTGr key not usable, so German keyboard users can't enter a pipe ("|"), tilde ("~") or a backslash ("\") character. Also the up and down keys are usually resulting in weird characters being pasted to the shell. Now all of that makes using a shell/terminal prompt quite interesting.