UNIX for Beginners Questions & Answers

Hello,

Root squash

Root squash is a reduction of the access rights for the remote superuser (root) when using identity authentication
(local user is the same as remote user). It is primarily a feature of NFS but may be available on other systems as well.

This problem arises when a remote file system is shared by multiple users. These users belong to one or multiple groups.
In Unix, every file and folder normally has separate permissions (read, write, execute) for the owner
(normally the creator of the file), for the group to which the owner belongs, and for the "world" (all other users).
This allows restriction of read and write access only to the authorized users while in general the NFS server must also be protected by firewall.

A superuser has more rights than an ordinary user, being able to change the file ownership, set arbitrary permissions, and
access all protected content. Even users that do need to have root access to individual workstations may not be authorized
for the similar actions on a shared file system. Root squash reduces rights of the remote root, making one no longer superuser.
On UNIX like systems, root squash option can be turned on and off in /etc/exports file on a server side.

After implementing the root squash, the authorized superuser performs restricted actions after logging into an NFS server directly
and not just by mounting the exported NFS folder.

2nd:
the nosuid, noexec and others are options which you can pass to the mount command (which performs the actual mounting).

Regards

It will, if a few criteria are met by all the involved nodes. Which criteria these are depends on the version of NFS you want to employ as i said already several posts above. In general: you need certain daemons to run but which that are depends on the version of NFS, because different versions need different daemons and you need certain open ports (but which these are again depends on the version you want to use) and a few other things too.

As you didn't answer which version you want to use no general answer to your question can be given.

Yes, but again: depending on the version of NFS you want to use there are different methods used.

I hope this helps.

bakunin

I think the /share in the previous post is the exported(=shared) directory on the NFS server. The given /share line is not a command; it is an entry in the /etc/exports file. The command exportfs -av activates the lines in the exports file.
On the NFS client(s) the mount command mounts the server's exported share to a local directory. Then all files in the mounted directory are located on the NFS server.
The export works on host(ip, network) level. Once mounted, the file owner and permissions decide on UID/GID level, just like the local files.