I just learning about daemon, by that time I came know avahi daemon can you please explain detaily about avahi daemon and why linux has a avahi user ?
In short: avahi is a Linux implementation of a protocol also known as "Rendezvous" or "Bonjour"). Its goal is to let devices, conected to the local network, to broadcast their IP-address together with their function . Hence the printer can from time to time broadcasts : My IP is 192.168.23.45 and I can print any postscript document with ipp prottocol; a NAS can say: My IP is 192.168.23.88 and I can stream music, save your bacups, and serve as a fileserver. If it is not what you want to hear on your network you can stop / disable the avahi daemon with standard
systemctl command. But if you run a cups-broadcast daemon, it will start the avahi itself.
Linux uses fictive users usualy for security reasons, not to give the attacker any chance to hack a process own by root. So you can see a
mysql users. The daemon, owened by such unprivileged user, gives less chance for the attacker to get the superuser rights.