Oracle 11g setup closes without errors on pre-requisite check

It looks like the hardening was a little to hard. Oracle does need some access to the server. You can revert back the chmods for ping, Oracle rdbms does not need it. /tmp/ is not required, a usable location for tmp is, mostly for scripting. The rdbms has it's own tricks and storage for sorts.

Never install Oracle as root; use the root.sh at the end of the installation to do the system tweeks required. On some platforms there is a root pre script that should run before installation. The Oracle installation scripts refuse to run using the root account and can be run using any other account.

The access to some server config files has been made a little too tight for the install user to check the prerequisites. If you know they are ok, it's ok. Proving they are ok is a little easier when support issues arise. Check the group ownership of the critical config files and add the Oracle installation user to that group to give it read access.

The problem is that your Oracle Client installation is in the system PATH before your Oracle Server installation (in fact, you even mention that it worked before you installed the client).

Proceed as follows:

1. Remove the Oracle Client as it's only confusing things. Use the uninstall option but afterwards check that the directory and the Oracle Client registry key is gone and remove by hand if necessary.

   (It's possible to get this working by having the Oracle client home in the path after the server home, but it's much simpler to just have the single install. An Oracle server installation already contains a complete Oracle client anyway).

2. Make sure that the path to the server's home is in your PATH. And no other Oracle home is in the path.

3. Make sure that your account is in the ORA_DBA group. Double check this, especially if you are using domains.

4. If all else fails, you could remove SQLNET.AUTHENTICATION_SERVICES=(NTS) from your sqlnet.ora as this will force you to use password authentication.