Permission denied /private/etc - sudo not possible !

Hello,

I have a new Mac for now one week and I have a problem with the access to some files. I would like to change the file /private/etc/hosts but the access to it is impossible: permission denied.

The next problem is that I can't execute sudo -s .. the result is:

sudo: unable to stat /etc/sudoers: Permission denied

sudo: no valid sudoers sources found, quitting

But the strange point is I think a step before, concerning the repertory /private/etc. Normally I have the permission to go into this repertory but when I try, it appears "permission denied".

For example:

ls -l /private/

total 0

drwxrw-rw- 87 root wheel 2958 21 fév 15:14 etc

drwxr-xr-x 2 root wheel 68 9 sep 23:24 tftpboot

drwxrwxrwt 4 root wheel 136 21 fév 15:14 tmp

drwxr-xr-x 24 root wheel 816 9 oct 13:54 var

So normally I should be able to read the content of /etc, no?

But when I execute :

-bash-3.2$ ls -l /private/etc/

ls: afpovertcp.cfg: Permission denied

ls: aliases: Permission denied

ls: aliases.db: Permission denied

ls: apache2: Permission denied

ls: asl: Permission denied

ls: asl.conf: Permission denied

ls: auto_home: Permission denied

ls: auto_master: Permission denied

ls: autofs.conf: Permission denied

ls: bashrc: Permission denied

...

ls: sudoers: Permission denied

ls: syslog.conf: Permission denied

ls: ttys: Permission denied

ls: xtab: Permission denied

ls: zshenv: Permission denied

As you can see all those files are unaccessible for me.. Even /private/etc/bashrc ! This is certainly also why I have a strange prompt : "-bash-3.2$" instead of my computer name et username.. And I didn't change it !

Please, could someone help me? I really don't understand the problem 😟