Talkd and the talk command

The "talk" command allows you to talk to other users on the same system. It could be useful for some cases e.g. when multiple users log in via SSH to the same system. Using it is very simple; to talk to someone the command is just

$ talk username tty

Of course, you can talk to users on another system as well:

$ talk username@hostname tty

In either case, the tty is optional. It is used if you wish to talk to a local user who is logged in more than once to indicate the appropriate terminal name. "tty" is of the form 'ttyXX', or 'pts/X'.

Setup

Using xinetd

1. Install inetutils, which contains talk and talkd. These also rely on xinetd. Optionally install screen.
2. Configure the xinetd service entry by editing /etc/xinetd.d/talk and setting "disable = no".
3. If you are using tcp_wrappers or something similar, add an entry to /etc/hosts.allow:

   talkd: 127.0.0.1

4. Now start xinetd.service.
5. If you are on the local system, you might need to start a screen session to make yourself show up on the "w" and "who" commands -- you need to show up there or talk will not work.
6. Allow write access in your terminal if needed:

   $ mesg y

Using systemd directly

Start talk.socket and talk.service.