Any change I made to /private/etc/hosts file can't be persisted. After a while(like 10 minitues), the file will be overwritten. How can I find out the root cause of this problem? Or can I make the file immutable like using chattr under Linux?
No suspicious software(like cisco VPN) is installed. No strange file exists(like /etc/hosts.ac). I do have installed some VPN software like tunnelblick and pulse secure.