This is the login program from util-linux-2.4, modified to use tcp wrappers for authentication instead of /etc/securetty (which is an admirable solution for multiuser machines with serial connections to terminals, but modern environments appear to be primarily tcp-ip connections to the machine.)

Login is not burdened with excessive portability or ease of configuration; it’s just a collection of files to download and compile. It’s stable (I use it in Mastodon Linux) and hasn’t been modified since the mid 1990s. It is composed of these text files:

Login is BSD-licensed except for the manual page, which is released under the GPL.