Selected RH302 RHCE Questions Answers

Do the following steps as:

1. Rename the file named.caching-nameserver.conf into named.conf file located into /var/named/chroot/etc

#mv /var/named/chroot/etc/named.caching-nameserver.conf /var/named/chroot/etc/named.conf

2. Check the permission and ownership as well as SELinux Context should be like as:

-rw-r----- root named system_u:object_r:named_conf_t /var/named/chroot/etc/named.conf

If selinux context is mismatch use the restorecon –R /var command

3.vi /etc/named.conf

zone “example.com” IN {

type master;

file “example.com.zone”;

};

/var/named/chroot/etc/named.conf file is used to register the zone as well as specify the global option for DNS server. There are two types of zone, i. Master, which contains the original data. ii. Slave, backup of master. Here is the example of master zone configuration.

4.vi /var/named/chroot/var/named/example.com.zone

$TTL 345345

@ IN SOA @ webmaster.example.com.(

101;Serial Number

1H;Refresh Time

1M;Retry Time

1W;Expire Time

1D;Minimum Time to Live

)

@ IN NS 192.100.0.X

www 0 IN A 192.100.0.1

www 0 IN A 192.100.0.2

www 0 IN A 192.100.0.3

www 0 IN A 192.100.0.4

www 0 IN A 192.100.0.5

3.service named start

4.rndc reload

5.chkconfig named on

6. Check the permission as well as SELinux Context should like this:

-rw-r--r-- root named root:object_r:named_zone_t /var/named/chroot/var/named/example.com.zone

If selinux context is mismatch use the restorecon –R /var command

7.service named start

8.rndc reload

9.chkconfig named on

Zone file should create on /var/named/chroot/var/named. Default Directory Path is specified on /var/named/chroot/etc/named.conf file.

$TTLTime To Live, How much seconds cache server stores the information about DNS. And Five Parameters specified Serial Number used by slave to synchronize withmaster server. Refresh and Retry Time used by slave server. NS is the Name (DNS) server where lookup the domain. A (Associated IP) for particular host.

Do the following steps as:

1.vi /etc/hosts.deny

vsftpd:ALL EXCEPT .example.com

We can secure the services using tcp_wrappers. There are main two files, /etc/hosts.allow and /etc/hosts.deny.

There will be three stage access checking

-Is access explicitly permitted? Means permitted from /etc/hosts.allow?

- Otherwise, Is access explicitly denied? Means denied from /etc/hosts.deny?

- Otherwise, by default permit access if neither condition matched.

To deny the services we can configure /etc/hosts.deny file using ALL and EXCEPT operation. Pattern of /etc/hosts.allow and /etc/hosts.deny file is:

Demon_list:client_list:options

In Client list can be either domain name or IP address.

Do the following steps as:

1.vi /etc/vsftpd/vsftpd.conf

anon_upload_enable=yes

chown_uploads=yes

chown_username=username

2.service vsftpd start| restart

3.directory owner should be ftp user: chown ftp directory path allowedto upload files.

4.Write permission should be set to owner user.

By default anonymous user can only download files from the ftp. Should write anon_upload_enable=yes to enable anonymous upload files. Default Directory for anonymous is /var/ftp.

Do the following steps as:

1.vi /etc/security/time.conf

login;*;user15|user16;Sa0000-2400

2.vi /etc/pam.d/login

accountrequiredpam_time.so

For Time based authentication, we should configured in /etc/security/time.conf

Syntax of /etc/security/time.conf

services;ttys;users;times

services

is a logic list of PAM service names that the rule applies to.

ttys

is a logic list of terminal names that this rule applies to.

users

is a logic list of users to whom this rule applies.

times

the format here is a logic list of day/time-range entries the days are specified by a sequence of two character entries, MoTuSa for example is Monday Tuesday and Saturday. Note that repeated days are unset MoMo = no day, and MoWk = all weekdays bar Monday. The two character combinations accepted are

Mo Tu We Th Fr Sa Su Wk Wd Al

the last two being week-end days and all 7 days of the week respectively. As a final example, AlFr means all days except Friday.

pam_time modules checks the file /etc/security/time.conf for authentication. So, we should call the pam_time modules in /etc/pam.d/login.