* A Plymouth agent used for querying passwords during boot-up
* A console agent used in similar situations if Plymouth is not available
* A GNOME agent which can be run as part of the normal user session which pops up a notification message and icon which when clicked receives the passphrase from the user. This is useful and necessary in case an encrypted system hard-disk is plugged in when the machine is already up.
-* A [`wall(1)`](http://man7.org/linux/man-pages/man1/wall.1.html) agent which sends wall messages as soon as a password shall be entered.
+* A [`wall(1)`](https://man7.org/linux/man-pages/man1/wall.1.html) agent which sends wall messages as soon as a password shall be entered.
* A simple tty agent which is built into "`systemctl start`" (and similar commands) and asks passwords to the user during manual startup of a service
* A simple tty agent which can be run manually to respond to all queued passwords