libnss-pool

What is the functionality of pool service?

The general idea behind the pool service is to use uid's from a predefined pool as a precofigured set of accounts with yet unknown names, so up to the number of preconfigured accounts getpwnam() calls, happening as a result of getent passwd username orsu will not fail but will return struct passwd results matching the name provided as getpwnam argument with the uid,gid,gecos,dir,shell details preconfigured for the used pool.

How to use it?

Simply compile like specified for nsswitch libraries:

./bootstrap.sh
./configure
make

Then copy the .so.2 file to the location used on your system,

cp ./libnss_pool.so.2 /usr/x86_64-linux-gnu/

Finally, add it to passwd database configuration of nsswitch.conf:

[root@localhost ~]# grep passwd /etc/nsswitch.conf
passwd:     files systemd pool