Red Hat Red Hat Certifications EX300 Questions & Answers

• Question 51:

  SIMULATION

  Configure the samba server, share /common, which can be browsed. The user harry can only read it. If it is needed, the password for harry is harryuser.

  Correct Answer: Please see explanation

  Explanation:

  

• Question 52:

  SIMULATION

  Configure an email server domain30.example.com, and it requests to send and receive emails from the local server or the user harry can send or receive emails from network. The email of user harry is /var/ spool/mail/harry. Please note: the DNS server has already been MX record analyzed.

  Correct Answer: Please see explanation

  Explanation:

  

• Question 53:

  SIMULATION Please set the selinux status as enforcing.

  Correct Answer: Please see explanation

  Explanation:

  

• Question 54:

  SIMULATION Please open the ip_forward and take effect permanently.

  Correct Answer: Please see explanation

  Explanation:

  

  If no “sysctl.conf” option, use these commands:

  

• Question 55:

  SIMULATION

  Configure a mail alias to your MTA, for example, send emails to harry but mary actually is receiving emails.

  Correct Answer: Please see explanation

  Explanation:

  

  Notice:

  This problem is a trap. The question no 31 requires that harry must be able to receive remote emails but the problems in the question no 32 requires mary to receive harry's emails. So harry must be added when you are deploying aliases.

• Question 56:

  SIMULATION

  Create a Shell script /root/program: The shell script will come back to “user” parameter when you are entering “kernel” parameter. The shell script will come back to “kernel” when you are entering “user” parameter. It will output the standard error when this script “usage:/root/program kernel|user” don't input any parameter or the parameter you inputted is entered as the requirements.

  Correct Answer: Please see explanation

  Explanation:

  

• Question 57:

  SIMULATION

  Given the kernel of a permanent kernel parameters: sysctl=1. It can be shown on cmdline after restarting the system. Kernel of /boot/grub/grub.conf should be a34dded finally, as:

  Correct Answer: Please see explanation

  Explanation:

  

• Question 58:

  SIMULATION Prevent Mary from performing user configuration tasks in your system.

  Correct Answer: Please see explanation

  Explanation:

  

  Conclusions:

  1. I find that it is common to add various service access limits in the exam RHCE. The exercises like: require one network segment can be accessed another network segments can not be accessed, the following are some conclusions for various service:

  tcp_wrappers:/etc/hosts.allow,/etc/hosts.deny

  tcp_wrappers can filter the TCP's accessing service. TCP whether has the filtering function which depends

  on this service whether use the function library of tcp_wrappers, or this service whether has the xinetd

  process of starting function of tcp_wrappers. tcp_wrappers's main configuration file is /etc/hosts.allow,/etc/

  hosts.deny.

  And the priority of the documents in hosts. allow is higher than hosts. deny. Visit will be passed if no match

  was found.

  sshd,vsftpd can use the filtering service of tcp_wrappers.

  

  Configuration example:

  Notice: The two configuration files’ syntax can refer to hosts_access (5) and hosts_options(5) sshd_configThere are four parameters in this configuration file: DenyUsers, AllowUsers, DenyGroups, AllowGroups, they are used to limit some users or user groups to proceed Remote Login through the SSH. These parameters’ priority level is DenyUsers->AllowUsers->DenyGroups->AllowGroups

  

  Configuration example:

  httpd Service

  Through the /etc/httpd/conf/httpd.conf in parameters, can add to control the url access. Just as:

  

  Notice:

  So pay attention, deny's and allow's priority level in order deny,allow is: the backer has the higher priority

  level. But here, allow's priority has a higher priority level.

  nfs Service

  nfs service directly control the visits through file /etc/exports, just as:

  

  samba Service

  Parameter hosts allow in /etc/samba/smb.conf which is used as Access Control, just as:

  

  2. Paying attention to use Mount parameters: _netdev,defaults when you are mounting ISCSI disk.

  3. Stop the NetworkManager

  /etc/init.d/NetworkManager stopchkconfig NetworkManager off

  4. When you are deploying ifcfg-ethX, add parameters:

  PEERDNS=no

  5. Empty the firewall in RHCSA、RHCE:

  6. Narrow lv steps:

  7. Mount the using command - swap which is newly added in /etc/fstab

  8. If Verification is not passed when you are installing software, can import public key: rpm import /etc/pki/ rpm…/…release and so on. In yum.repo, you also can deploy gpgkey, for example, gpgkey=/etc/pki/rpm…/ …release

  9. When you are using “Find” command to search and keep these files, paying attention to use cp -a to copy files if you use user name and authority as your searching methods.

  

  

• Question 59:

  SIMULATION

  In accordance with the following requirements to deploy ssh login service: harry belongs to example.com which can remote login your systems. However, users of remote.test cannot use ssh login to your machine.

  Correct Answer: Please see explanation

  Explanation:

  

  Notice:

  tcp_wrappers has two configuration files and their priority level is /etc/hosts.allow->/etc/hosts.deny

• Question 60:

  SIMULATION

  Via nfs service share the /common directory in your system, just doing ONE share in example.com domain.

  Correct Answer: Please see explanation

  Explanation: