root@UbuntuServer:/mnt/test# mount -o loop CentOS-7-x86_64-Everything-1804.iso /mnt/test2/
mount: /mnt/test/CentOS-7-x86_64-Everything-1804.iso: failed to setup loop device: Operation not supported

root@UbuntuServer:~# curlftpfs ftp://randeer:randeer@192.168.0.2 /mnt/test/
root@UbuntuServer:~# ls -l
total 0
root@UbuntuServer:~# cd /mnt/test/
root@UbuntuServer:/mnt/test# ls
CentOS-7-x86_64-Everything-1804.iso  new public             rootnewprivate.ppk
fromcentos.txt                       randeernewprivate.ppk  rootpub
root@UbuntuServer:/mnt/test# mount CentOS-7-x86_64-Everything-1804.iso /mnt/test                                                                                        2/ -t iso9600 -o loop
mount: /mnt/test/CentOS-7-x86_64-Everything-1804.iso: failed to setup loop devic                                                                                        e: Operation not supported