Comment 6 for bug 1880240

I got it: /lib/systemd/system/uucp.socket

"
[Unit]
Description=UUCP server activation socket

[Socket]
ListenStream=540
Accept=true

[Install]
WantedBy=sockets.target
"

Does not seem to be autogenerated. But it does not base on the xinetd config and therefore security settings are missng:

"
service uucp
{
        only_from = 0.0.0.0
        port = 540
        socket_type = stream
        protocol = tcp
        user = uucp
        server = /usr/sbin/uucico
        server_args = -I /etc/uucp/config -l
        type = UNLISTED
        wait = no
        bind = 0.0.0.0
}
"

Only_from and bind are important.