Practice Free RH302 RHCE (Redhat Certified Engineer) Exam Questions Answers With Explanation

When user creates the file/directory, user owner will be user itself and group owner will be the primary group of the user.

There is one Special Permission SGID , when you set the SGID bit on directory,When users creates the file/directory automatically owner group will be same as a parent.

chmod g+s /data

Verify using: ls -ld /data

You will get: drwxrws---

Note: Examiner will provide you the Installation startup CD. And here mentioned size may vary see on the exam paper.

1.Insert the CD on CD-ROM and start the system.

2.In Boot: Prompt typelinux askmethod

3. It will display the Language, keyboard selection.

4. It will ask you for the installation method.

5. Select the FTP from the list

6. It will ask the IP Address, Net mask, Gateway and Name Server. Select Use

Dynamic IP Configuration: because DHCP Server will be configured in your exam lab.

7. It will ask for the FTP site name and Redhat Enterprise Linux Directory.

Specify the FTP Server: 192.168.0.254

Directory: pub?Because anonymous login on /var/ftp.

8. After Connecting to the FTP Server Installation will start. Go up to the partition screen by selecting the different Options.

9. Create the partition According to the Question because Size and what-what partition should you create at installation time is specified in your question

10. Then select the MBR Options, time zone and go upto package selections.

It is another Most Important Time of installation. Due to the time limit, you should be

care about the installation packages. At Exam time you these packages are enough.

X-Window System

GNOME Desktop

(these two packages are generally not required)

Administration Tools.

System Tools

Windows File Server

FTP Servers

Mail Servers

Web Servers

Network Servers

Editors

Text Based Internet

Server Configuration Tools

Printing Supports

When installation will complete, your system will reboot. Jump for another Question.

Do the following steps as:

1.chgrp sysusers /storage

2.Verify using ls -ld /storage command. You should get like

drwxr-x--- 2 root sysusers 4096 Mar 16 17:59 /storage

chgrp command is used to change the group ownership of particular files or directory.

Another way you can use the chown command.

chown root:sysusers /storage

Do the following steps as:

cat >schedule

*/2 * * * * /bin/echo “Hello World” >/dev/tty8

crontab schedule

Verify using: crontab –l

service crond restart

Cron helps to schedule on recurring events. Pattern of Cron is:

MinuteHourDay of MonthMonthDay of WeekCommands

0-590-231-311-120-7 where 0 and 7 means Sunday.

Note * means every. To execute the command on every two minutes */2.

To add the scheduled file on cron job: crontab filename

To List the Cron Shedule: crontab –l

To Edit the Schedule: crontab –e

To Remove the Schedule: crontab –r

By default user1 can remove user2’s files due to directory permission to group member. We can prevent of deleting files from others users using Sticky Bits.

chmod o+t /data

Verify /data: ls -ld /data

You will get: drwxrwx—T

Do the following steps as:

1.usermod -G sysusers jeff

2.usermod –G sysuser marion

3.Verify by reading /etc/group file

Using usermod command we can make user belongs to different group. There are two types of group one primary and another is secondary. Primary group can be only one butuser can belongs to more than one group as secondary.

usermod -g groupname username?To change the primary group of the user

usermod -G groupname username?To make user belongs to secondary group.

Do the following steps as:

1.echo “1” >/proc/sys/net/ipv4/ip_forward

2.vi /etc/sysctl.conf

net.ipv4.ip_forward = 1

If you want to use the Linux System as a Router to make communication between different networks, you need enable the IP forwarding. To enable on running session just set value 1 to /proc/sys/net/ipv4/ip_forward. As well as automatically turn on the IP forwarding features on next boot set on /etc/sysctl.conf file.

Do the following steps as:

1.vi /etc/sysconfing/network

NETWORKING=yes

HOSTNAME=station?.example.com

GATEWAY=192.168.0.254

2.service network restart

Or

1.vi /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0

ONBOOT=yes

BOOTPROTO=static

IPADDR=X.X.X.X

NETMASK=X.X.X.X

GATEWAY=192.168.0.254

2.ifdown eth0

3.ifup eth0

Do the following steps as:

1. Create the repository file

#vi /etc/yum.repos.d/server1.repo

[station?]

name=station?

baseurl=ftp://server1.example.com/pub/

enabled=1

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release

# yum install

Do the following steps as:

1.lvextend –L+200M /dev/test0/testvolume1

Use lvdisplay /dev/test0/testvolume1)

2.ext2online –d /dev/test0/testvolume1

lvextend command is used the increase the size of Logical Volume. Other command lvresize command also here to resize. And to bring increased size on online we use the ext2online command.

Do the following steps as:

1.vi /etc/hosts.deny

ALL:.cracker.org EXCEPT trusted.cracker.org

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/hosts.deny

sshd: 192.168.0. EXCEPT 192.168.0.4

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/exports

/data*.example.com(rw,sync)

2.service nfs start

3.service portmap restart

4.chkconfig nfs on

5.chkconfig portmap on

In Linux to share the data we use the /etc/exports file. Pattern is:

Pathclient(permission)

Shared Directory Path, Client can be single host or domain name or ip address. Permission should specify without space with client lists in parentheses.

Do the following steps as:

1.vi /etc/hosts.deny

vsftpd:ALL EXCEPT .example.com

or

1.vi /etc/hosts.deny

vsftpd:ALL

2.vi /etc/hosts.allow

vsftpd:.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/samba/smb.conf

[global]

netbios name=station?

workgroup=station?

security=user

smb passwd file=/etc/samba/smbpasswd

encrypt passwords=yes

hosts allow= .example.com

[data]

path=/data

public=no

writable=no

browsable=yes

2.smbpasswd -a eric

3.service smb start

4.chkconfig smb on

/etc/samba/smb.conf. There are some pre-defined section, i. global?use to define the global options, ii. Printers?use to share the printers, iii. homes?use the share the user’s home directory.

Security=user?validation by samba username and password. May be there are other users also. To allow certain share to certain user we should use valid users option.

smbpasswd?Helps to change user’s smb password. –a option specifies that the username following should be added to the local smbpasswd file.

Do the following steps as:

1. Insert the CD on CD-ROM and start the system.

2. In Boot: Prompt typelinux askmethod

3. It will display the language, keyboard selection.

4. It will ask you for the installation method.

5. Select the NFS Image from the list

6. It will ask the IP Address, Net mask, Gateway and Name Server. Select Use

Dynamic IP Configuration: because DHCP Server will be configured in your exam lab.

7. It will ask for the NFS Server Name and Redhat Enterprise Linux Directory.

Specify the NFS Server: 192.168.0.254

Directory: /var/ftp/pub

8. After Connecting to the NFS Server Installation start in GUI. Go up to the partition screen by selecting the different Options.

9. Create the partition According to the Question because Size and what-what partition should you create at installation time is specified in your question

10.Create the two RAID partitions having equal size of remaining all free space.

11.Click on RAID button

12.Type mount point /data

13.Select RAID Level 0

14.Click on ok

15. Then select the MBR Options, time zone and go upto package selections.

It is another Most Important Time of installation. Due to the time limit, you should care about the installation packages. At Exam time you these packages are enough.

X-Window System

GNOME Desktop

(these two packages are generally not required)

Administration Tools.

System Tools

Windows File Server

FTP Servers

Mail Servers

Web Servers

Network Servers

Editors

Text Based Internet

Server Configuration Tools

Printing Supports

When installation will complete, your system will reboot. Jump for another Question.

Do the following steps as:

1.vi /etc/xinetd.d/telnet

service telnet {

only_from=192.168.0.0/24

access_times=09:00-17:00

}

2.chkconf telnet on

3.service xinetd restart

xinetd based services can manage by specifying host and time parameters. Only_from means connection allowed network, remaining hosts explicitly deny. access_times specify when service is available.

Do the following steps as:

1.vi /etc/hosts.deny

dovecot:ALL EXCEPT .example.com EXCEPT station20.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.

IPP( Internet Printing Protocol), allows administrator to manage printer through browser so CUPS is called Internet Printing Protocol based on HTTP. We can Install the printer either through: system-confing-printer tool or through Browser.

1.Open the browser and Type on address: http://localhost:631 ?CUPS (Common Unix Printing System) used the IPP protocol. CUPS use the 631 port.

2.Click on Manage Printer.

3.Click on Add Printer.

4.Type Printer name, Location, Description.

5.Select Device for bb. (Select IPP).

6.Device URL: ipp://192.168.0.254/ipp/ queue name?Same printer name of shared printer.

7.Select Model/Driver RAW printer.

8.service cups restart

Do the following steps as:

1.useradd jane

2.useradd john

useradd command is used to create the user. All user’s information stores in /etc/passwd and user;s shadow password stores in /etc/shadow.

Note: Examiner will provide you the Installation startup CD. And here mentioned size may vary see on the exam paper.

1.Insert the CD on CD-ROM and start the system.

2.In Boot: Prompt typelinux askmethod

3. It will display the language, keyboard selection.

4. It will ask you for the installation method.

5. Select the NFS Image from the list

6. It will ask the IP Address, Net mask, Gateway and Name Server. Select Use

Dynamic IP Configuration: because DHCP Server will be configured in your exam lab.

7. It will ask for the NFS Server Name and Redhat Enterprise Linux Directory.

Specify the NFS Server: 192.168.0.254

Directory: /var/ftp/pub

8. After Connecting to the NFS Server Installation start in GUI. Go up to the partition screen by selecting the different Options.

9. Create the partition According to the Question because Size and what-what partition should you create at installation time is specified in your question

10. Then select the MBR Options, time zone and go upto package selections.

It is another Most Important Time of installation. Due to the time limit, you should care about the installation packages. At Exam time you these packages are enough.

X-Window System

GNOME Desktop

(these two packages are generally not required)

Administration Tools.

System Tools

Windows File Server

FTP Servers

Mail Servers

Web Servers

Network Servers

Editors

Text Based Internet

Server Configuration Tools

Printing Supports

When installation will complete, your system will reboot. Jump for another Question.

The LVM system organizes hard disks into Logical Volume (LV) groups. Essentially, physical hard disk partitions (or possibly RAID arrays) are set up in a bunch of equal-sized chunks known as Physical Extents (PE). As there are several other concepts associated with the LVM system, let's start with some basic definitions:

Physical Volume (PV)is the standard partition that you add to the LVM mix. Normally, a physical volume is a standard primary or logical partition. It can also be a RAID array.

Physical Extent (PE)is a chunk of disk space. Every PV is divided into a number of equal sized PEs. Every PE in a LV group is the same size. Different LV groups can have different sized PEs.

Logical Extent (LE)is also a chunk of disk space. Every LE is mapped to a specific PE.

Logical Volume (LV)is composed of a group of LEs. You can mount a filesystem such as /home and /var on an LV.

Volume Group (VG)is composed of a group of LVs. It is the organizational group for LVM. Most of the commands that you'll use apply to a specific VG.

1.Verify the size of Logical Volume:lvdisplay /dev/vg0/lv1

2.Verify the Size on mounted directory:df –h or df –h mounted directory name

3.Use :lvextend –L+400M /dev/vg0/lv1

4. ext2online –d /dev/vg0/lv1?to bring extended size online.

5. Again Verify using lvdisplay and df –h command.

Do the following steps as:

1.vi /etc/hosts.deny

in.telnetd:ALL EXCEPT 192.168.0.

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. Here in.telnetd is the telnet server program name.

Redhat Enterprise Linux 5 Supports the RAID LEVEL 0, RAID LEVEL 1, RAID LEVEL 5 and RAID LEVEL 6 at installation time. You can create it at installation time later no need to type lots of commands for RAID.

At Installation Time:

Create the partitions using diskdruid.

Create the Partitions having File system Type Software RAID.

Click on RAID button

Type the Mount Point

Select File system type

Select RAID Level

Select Partitions/disks as a member of RAID.

viii.Click on ok

After Installation: We can create the RAID Device after Installation on command-line.

Create the Two partitions having equal size. (Specify the Size using Cylinder, find the remaining cylinder and divide by 2).

Change the Partition ID to fd (Linux raid Autodetect) by typing t.

Type w?To write on partitions table.

Use partprobe command to synchronic the partition table.

Use: mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/hda? /dev/hda?

Verify the RAID: mdadm --detail /dev/md0

mkfs -t ext3 /dev/md0

mount /dev/md0 /data

vi /etc/fstab

/dev/md0/dataext3defaults0 0

Verify mounting devices using mount command.

When user creates the file/directory, user owner will be user itself and group owner will be the primary group of the user.

There is one Special Permission SGID bit, when you set the SGID bit on directory,When users creates the file/directory automatically owner group will be same as a parent directory.

chmod g+s /data

Verify using: ls -ld /data

You will get: drwxrws---

Do the following steps as:

groupadd training

To create a group we use the groupadd command.

Verify from: cat /etc/group whether group added or not?

Do the following steps as:

1.useradd eric

Very tricky question given to you that this user should not belongs to sysadmin group.

Do the following steps as:

1.chmod 770 /archive

2.Verify using : ls –ld /archive

Preview should be like:

drwxrwx--- 2 root sysuser 4096 Mar 16 18:08 /archive

To change the permission on directory we use the chmod command. According to the question that only the owner user (root) and group member (sysuser) can fully access the directory so: chmod 770 /archive

Do the following steps as:

1.usermod -G sysuser jackie

2.usermod –G sysuser curtin

3.Verify by reading /etc/group file

Using usermod command we can make user belongs to different group. There are two types of group one primary and another is secondary. Primary group can be only one but user can belongs to more than one group as secondary.

usermod -g groupname username?To change the primary group of the user

usermod -G groupname username?To make user belongs to secondary group.

Do the following steps as:

1.rpm –ivh ftp://server1.example.com/pub/zsh-*

2.Package will install

rpm command is used to install, update and remove the package, -i means install, -v means verbose and -h means display the hash mark.

Do the following steps as:

1.vi /etc/samba/smb.conf

[global]

netbios name=station?

workgroup=station?

security=user

smb passwd file=/etc/samba/smbpasswd

encrypt passwords=yes

hosts allow= .example.com

[data]

path=/data

public=no

writable=no

write list=john

browsable=yes

2.smbpasswd -a john

3.service smb start

4.chkconfig smb on

/etc/samba/smb.conf. There are some pre-defined section, i. global?use to define the global options, ii. Printers?use to share the printers, iii. homes?use the share the user’s home directory.

Security=user?validation by samba username and password. May be there are other users also. To allow certain share to certain user we should use valid users option.

smbpasswd?Helps to change user’s smb password. –a option specifies that the username following should be added to the local smbpasswd file.

If any valid users option is not specified, then all samba users can access the shared data. By Default shared permission is on writable=no means read only sharing. Write listoption is used to allow write access on shared directory to certain users or group members.

Do the following steps as:

1.vi /etc/exports

/data*.example.com(rw,sync)

2.service nfs start | restart

3.service portmap start | restart

4.chkconfig nfs on

5.chkconfig portmap on

In Linux to share the data we use the /etc/exports file. Pattern is:

Pathclient(permission)

Shared Directory Path, Client can be single host or domain name or ip address. Permission should specify without space with client lists in parentheses. NFS is RPC service so portmapper service should restart after starting the nfs service.

Do the following steps as:

1.vi /etc/hosts.deny

vsftpd:ALL EXCEPT .example.com

or

1.vi /etc/hosts.deny

vsftpd:ALL

2.vi /etc/hosts.allow

vsftpd:.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.

Note: In Exam Lab there will be two different domain example.com which is known as local domain and another is cracker.org which is called non trusted domain. So only from .example.com means allow only to example.com deny to every one.

Do the following steps as:

1.vi /etc/vsftpd.ftpusers

user1

user2

2.service vsftpd start| restart

Using /etc/vsftpd.ftpusers file we can deny to certain users to access files via ftp. As well as there is another file named /etc/vsftpd.user_list can be used to allow or to deny to users.

Do the following steps as:

1.vi /etc/security/access.conf

-:jack:ALL EXCEPT station10.example.com

2.vi /etc/pam.d/system-auth

accountrequired/lib/security/pam_access.so

/etc/security/access.conf file helps to allow or deny login to users on the basis of origin.

Syntax of /etc/security/access.conf

permission : users : origins

The first field should be a "+" (access granted) or "-" (access denied) character.

The second field should be a list of one or more login names, group names, or ALL (always matches). A pattern of the form user@host is matched when the login name matches the "user" part, and when the "host" part matches the local machine name.

The third field should be a list of one or more tty names (for non-networked logins), host names, domain names (begin with "."), host addresses, internet network numbers (end with "."), ALL (always matches) or LOCAL (matches any string that does not contain a "." character).

The EXCEPT operator makes it possible to write very compact rules

Do the following steps as:

1.touch /etc/nologin

2.vi /etc/securetty

comment all available terminall then first.

If /etc/nologin file is created, then pam modules pan_nologin deny to all non-root users to login locally.

/etc/pam.d/login file calls the module.

#%PAM-1.0

auth requiredpam_securetty.so

auth requiredpam_stack.so service=system-auth

auth requiredpam_nologin.so

account requiredpam_stack.so service=system-auth

password requiredpam_stack.so service=system-auth

# pam_selinux.so close should be the first session rule

session requiredpam_selinux.so close

session requiredpam_stack.so service=system-auth

session optionalpam_console.so

# pam_selinux.so open should be the last session rule

session requiredpam_selinux.so multiple open

pam_securetty modules checks the /etc/securetty file, which terminal are available to root. If terminal is not available in this file then pam_securetty module deny to login on unavailable terminal to root user.

Do the following steps as:

1.iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -p tcp -j SNAT –to-source 202.2.2.2.

POSTROUTING?This filter point handles packets immediately prior leaving the system.

When Packets leave the system all’s source address change to 202.2.2.2 and can access the internet.

iptables is the build-in firewall tools, used to filter the packets and for nat. By identifying Source Address, Destination Address, type of protocol, source and destination port we can filter the packets.

-s?Source Address

-d?Destination Address

-p?Layer 3 Protocol

-d?Destination Address

--sport?Source Prot

--dport?Destination Port

-i?Incoming Interface

-o?Outgoing Interface

-t?Table either filter or nat or mangle

-A?Chain can be either INPUT, OUTPUT, FORWARD, PREROUTING, POSTROUTING.

By default all mails to user will send to user’s spool directory. Nothing to do.

Do the following steps as:

1.vi /etc/samba/smb.conf

[global]

netbios name=station?

workgroup=station?

security=user

smb passwd file=/etc/samba/smbpasswd

encrypt passwords=yes

hosts allow= .example.com

[data]

path=/data

public=no

writable=no

browsable=yes

2.smbpasswd -a jeff

3.service smb start

4.chkconfig smb on

/etc/samba/smb.conf. There are some pre-defined section, i. global?use to define the global options, ii. Printers?use to share the printers, iii. homes?use the share the user’s home directory.

Security=user?validation by samba username and password. May be there are other users also. To allow certain share to certain user we should use valid users option.

smbpasswd?Helps to change user’s smb password. –a option specifies that the username following should be added to the local smbpasswd file.

Do the following steps as:

1.iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -p tcp -j SNAT –to-source 202.2.2.2.

POSTROUTING?This filter point handles packets immediately prior leaving the system.

When Packets leave the system all’s source address change to 202.2.2.2 and can access the internet.

iptables is the build-in firewall tools, used to filter the packets and for nat. By identifying Source Address, Destination Address, type of protocol, source and destination port we can filter the packets.

-s?Source Address

-d?Destination Address

-p?Layer 3 Protocol

-d?Destination Address

--sport?Source Prot

--dport?Destination Port

-i?Incoming Interface

-o?Outgoing Interface

-t?Table either filter or nat or mangle

-A?Chain can be either INPUT, OUTPUT, FORWARD, PREROUTING, POSTROUTING.

Do the following steps as:

ftpftp.server1.example.com

Download thewww.html

Check the SELinux context of index page , should like this:

-rw-r--r-- root root system_u:object_r:httpd_sys_content_t /var/www/html/index.html

If SELinux Context is mismatched, use the restorecon –R /var command

move the downloaded file into /var/www/html

Rename the file into index.html

Check using linkshttp://stationx.example.com

/var/www/html is the default directory for httpd service. Index.html is the default directory index. To set the default page without configuring virtualhost copy the file as a index.html in /var/www/html.

Do the following steps as:

1.vi /etc/xinetd.d/telnet

service telnet {

only_from=192.168.0.0/24

access_times=09:00-17:00

}

2.chkconf telnet on

3.service xinetd restart

xinetd based services can manage by specifying host and time parameters. Only_from means connection allowed network, remaining hosts explicitly deny. access_times specify when service is available.

Do the following steps as:

1.vi /etc/hosts.deny

dovecot:ALL EXCEPT .example.com, .my133t.org

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/security/access.conf

-:jack:ALL EXCEPT station10.example.com

2.vi /etc/pam.d/system-auth

accountrequired/lib/security/pam_access.so

/etc/security/access.conf file helps to allow or deny login to users on the basis of origin.

Syntax of /etc/security/access.conf

permission : users : origins

The first field should be a "+" (access granted) or "-" (access denied) character.

The second field should be a list of one or more login names, group names, or ALL (always matches). A pattern of the form user@host is matched when the login name matches the "user" part, and when the "host" part matches the local machine name.

The third field should be a list of one or more tty names (for non-networked logins), host names, domain names (begin with "."), host addresses, internet network numbers (end with "."), ALL (always matches) or LOCAL (matches any string that does not contain a "." character).

The EXCEPT operator makes it possible to write very compact rules

Do the following steps as:

1.vi /etc/hosts.deny

sshd:ALL EXCEPT .example.com

or

1.vi /etc/hosts.deny

sshd:ALL

2.vi /etc/hosts.allow

sshd:.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.touch /etc/nologin

2.vi /etc/securetty

comment all available terminall then first.

If /etc/nologin file is created, then pam modules pan_nologin deny to all non-root users to login locally.

/etc/pam.d/login file calls the module.

#%PAM-1.0

auth requiredpam_securetty.so

auth requiredpam_stack.so service=system-auth

auth requiredpam_nologin.so

account requiredpam_stack.so service=system-auth

password requiredpam_stack.so service=system-auth

# pam_selinux.so close should be the first session rule

session requiredpam_selinux.so close

session requiredpam_stack.so service=system-auth

session optionalpam_console.so

# pam_selinux.so open should be the last session rule

session requiredpam_selinux.so multiple open

pam_securetty modules checks the /etc/securetty file, which terminal are available to root. If terminal is not available in this file then pam_securetty module deny to login on unavailable terminal to root user.

Do the following steps as:

1.vi /etc/hosts.deny

vsftpd:ALL EXCEPT .example.com

or

1.vi /etc/hosts.deny

vsftpd:ALL

2.vi /etc/hosts.allow

vsftpd:.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.First check the size of Logical Volume: lvdisplay /dev/vo/myvol

2.Make sure that the filesystem is in a consistent state before reducing:

# fsck –f /dev/vo/myvol

3.Now reduce the filesystem by 200MB.

# resize2fs /dev/vo/myvol 200M

4.It is now possible to reduce the logical volume.

#lvreduce /dev/vo/myvol –L 200M

4.Verify the Size of Logical Volume: lvdisplay /dev/vo/myvol

5.Verify that the size comes in online or not: df -h

Maintenance mode also known as emergency mode. System boots on emergency mode when file system error occurred. It is due to unknown partition, bad filesystem specified in /etc/fstab. To slove follow the steps

Give the Root password

fdisk –l?Verify the Number of parations.

Identify the Root partition, e2label /dev/hda1, e2label /dev/hda2…..

Remount the root partation on rw mode: mount –o remount,defaults /dev/hda6 /

vi /etc/fstab

Correct all partitions, mount point, mount options, file system etc.

6.Press ctrl+d

While you load the X Window System, you will get the problem. To troubleshoot follow the following steps:

1.Check the /tmp is full ?

2.Check your quota, hard limit is already crossed ?

3.Check xfs service is running ?

4.Boot the system on runlevel 3 and execute the system-config-display command

5.Edit the /etc/inittab to set default runlevel 5.

id:5:initdefault:

Do the following steps as:

1. /proc is the virtual filesystem, we use /proc to modify the kernel parameters at running time.

# echo “1” >/proc/sys/net/ipv4/ip_forward

2. /etc/sysctl.conf?when System Reboot on next time, /etc/rc.d/rc.sysinit scripts reads the file /etc/sysctl.conf. To enable the IP forwarding on next reboot also you need to set the parameter.

net.ipv4.ip_forward=1

Here 0 means disable, 1 means enable.

To understand the role of a boot loader, take a step back from Linux. When you boot your computer, the BIOS starts by detecting basic hardware, including your hard drives. Once it's done, it looks for the boot loader on the Master Boot Record of the first available disk. If you're working with an older PC, the BIOS can't find your boot loader unless it's located within the first 1,024 cylinders of the hard disk.

Newer BIOSes overcome this problem with Logical Block Addressing, which is also known as LBA mode. LBA mode reads 'logical' values for the cylinder, head, and sector, which allows the BIOS to 'see' a larger disk drive.

If you have multiple hard drives, there is one more caveat. If your drives are IDE hard drives, the /boot directory must be on a hard drive attached to the primary IDE controller. If your drives are all SCSI hard drives, the /boot directory must be located on a hard drive with SCSI ID 0 or ID 1. If you have a mix of hard drives, the /boot directory must be located on either the first IDE drive or a SCSI drive with ID 0. In other words, this is not an issue on the Red Hat exams unless the computer that you're tested on has more than two hard drives. And I believe that's less likely, as that would increase the cost of the exam.

If you are getting the Kernel panic error, it means it is boot loader related problem. Redhat Enterprise Linux uses the GRUB boot loader. You can pass the kernel parameter from the boot loader as well as you can correct the kernel parameter passing from boot loader from GRUB screen at boot time.

GRUB boot loader configuration file is: /etc/grub.conf

And Correct Configuration is:

default=0

timeout=5

splashimage=(hd0,0)/grub/splash.xpm.gz

hiddenmenu

title Red Hat Enterprise Linux ES (2.6.9-5.EL)

root (hd0,0)

kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/ rhgb quiet

initrd /initrd-2.6.9-5.EL.img

Probably miss-configured the boot loader, so giving this problem. You can pass the correct parameter from GRUB prompt:

Table 3-3:GRUB Editing Commands

Command

Description

b

Boot the currently listed operating system

d

Delete the current line

e

Edit the current line

o

Create an empty line underneath the current line

O

Create an empty line above the current line

If you know all parameters and sequence of the boot loader you can enter in command prompt also.

Press c on GRUB screen.

Grub>root (hd0,0)

grub>kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/ rhgb quiet

grub>initrd /initrd-2.6.9-5.EL.img

grub>boot

When root unable to login into the system think:

1. Is password correct?

2. Is account expired?

3. Is terminal Blocked?

Do these Steps:

Boot the System on Single user mode.

Change the password

Check the account expire date by using chage –l root command.

If account is expired, set net expire date: chage –E “NEVER” root

Check the file /etc/securetty?Which file blocked to root login from certain terminal.

If terminal is deleted or commented write new or uncomment.

Reboot the system and login as a root.

You should know about the /etc/inittab file, where default runlevel will define. And Much more runlevel specific Scripts are called here.

Actually that problem will occur if you don’t specify the default runlevel.

Reboot the system

Boot the System on single user mode.

Except for a normal boot of Linux, single-user mode is the most commonly used option. This is the system maintenance mode for experienced Linux administrators. It allows you to perform clean backups and restores to any partitions as needed from local hardware. It also allows you to run administration commands, recover or repair password and shadow password files, run filesystem checks, and so forth.

vi /etc/inittab and Write

id:runlevel:initdefault:

Standard Runlevels in RedHat Enterprise Linux

Runlevel

Description

0

Halt

1

Single-user mode, for maintenance (backups/restores) and repairs

2

Multiuser, without networking

3

Multiuser, with networking

4

Unused

5

X11, defaults to a GUI login screen. Logins bring the user to a GUI desktop.

6

Reboot (never set initdefault in /etc/inittab to this value!)

We can control the services for current session and for next boot time also. For current Session, we use service servicename start or restart or stop or status. For automatically on next reboot time:

chkconfig servicename on or off

eg: chkconfig nfs on

chkconfig portmap on

or

ntsysv

Select the nfs and portmap services.

Reboot the system and identify whether services are running or not.

Do the following steps as:

1.Verify the File whether Shared or not ? : cat /etc/exports

2.Start the nfs service: service nfs start

3.Start the portmap service: service portmap start

4.Make automatically start the nfs service on next reboot: chkconfig nfs on

5.Make automatically start the portmap service on next reboot: chkconfig portmap on

6.Verify either sharing or not: showmount –e localhost

7.Check that default firewall is running on system ? if running flush the iptables using iptables –F and stop the iptables service.

We know that every files/directories are owned by certain user and group. And Permissions are defines to owner user, owner group and other.

-rwxr-x---?Full permission to owner user, read and write to owner group and no permission to others.

According to question: We should give the full permission to user user1 without changing the previous permission.

ACL (Access Control List), in ext3 file system we can give permission to certain user and certain group without changing previous permission. But that partition should mount using acl option. Follow the steps

vi /etc/fstab

/dev/hda14/dataext3defaults,acl0 1

Either Reboot or use: mount –o remount /data

setfacl –m u:user1:rwx /data

Verify using: getfacl /data

It is due to either default runlevel or runlevel specific scripts.

id:?:initdefault:?Where default runlevel is specified. It shouldn’t be 6.

l3:3:wait:/etc/rc.d/rc 6?It reads the scripts of runlevel 6 while booting system on rulevel 3.

It should be like:

si::sysinit:/etc/rc.d/rc.sysinit

l0:0:wait:/etc/rc.d/rc 0

l1:1:wait:/etc/rc.d/rc 1

l2:2:wait:/etc/rc.d/rc 2

l3:3:wait:/etc/rc.d/rc 3 Should be like this

l4:4:wait:/etc/rc.d/rc 4

l5:5:wait:/etc/rc.d/rc 5

l6:6:wait:/etc/rc.d/rc 6

Do the following steps as:

Use fdisk /dev/hda?To create new partition.

Type n?For New partitions

It will ask for Logical or Primary Partitions. Press l for logical.

It will ask for the Starting Cylinder: Use the Default by pressing Enter Key.

Type the Size: +100M?You can Specify either Last cylinder of Size here.

Press P to verify the partitions lists and remember the partitions name.

Press w to write on partitions table.

Either Reboot or use partprobe command.

Use mkfs –t ext3 /dev/hda?

Or

mke2fs –j /dev/hda? ?To create ext3 filesystem.

vi /etc/fstab

Write:

/dev/hda?/dataext3defaults0 0

Verify by mounting on current Sessions also:

mount /dev/hda? /data

Do the following steps as:

vi /etc/resolv.conf

nameserver 172.24.254.254

host server1.example.com

Do the following steps as:

1.rpm –ivhftp://server1/example.com/pub/updates/zsh-*

or

1.Login to ftp server : ftpftp://server1.example.comusing anonymous user.

2.Change the directory: cd pub and cd updates

3.Download the package: mget zsh-*

4.Quit from the ftp prompt : bye

5.Install the package

6.rpm -ivh zsh-*

7.Verify either package is installed or not : rpm -q zsh

To automatically mount at boot time we use the /etc/fstab file. Because /etc/rc.d/rc.sysinit file reads and mount all file system specified in /etc/fstab. To mount Network Sharing Files also use the /etc/fstab but filesystem is nfs.

vi /etc/fstab

192.168.0.254:/data/commonnfsdefaults0 0

reboot the system.

By Default system accept the logs only generated from local host. To accept the Log from other host configure:

vi /etc/sysconfig/syslog

SYSLOGD_OPTIONS="-m 0 -r"

Where

-m 0 disables 'MARK' messages.

-r enables logging from remote machines

-x disables DNS lookups on messages recieved with -r

service syslog restart

Do the following steps as:

Steps of Creating LVM:

Physical Disk1

Physical Disk2

Physical Disk3

Physical Volume

Volume Group

Logical Volume 1

Logical Volume 2

Logical Volume 3

1.pvcreate /dev/hda8 /dev/hda9 /dev/hda10

?pvdisplay command is used to display the information of physical volume.

2.vgceate test0 /dev/hda8 /dev/hda9 /dev/hda10

?vgdisplay command is used to display the information of Volume Group.

3.lvcreate –L 250M –n testvolume1 test0

?lvdisplay command is used to display the information of Logical Volume.

4.lvcreate –L 250M –n testvolume2 test0

5.mkfs –t ext3 /dev/test0/testvolume1

6.mkfs –t ext3 /dev/test0/testvolume2

7.mkdir /lvtest1

8.mkdir /lvtest2

9.mount /dev/test0/testvolume1 /lvtest1

10.mount /dev/test0/testvolume2 /lvtest2

11.vi /etc/fstab

/dev/test0/testvolume2/lvtest2ext3defaults0 0

/dev/test0/testvolume1/lvtest1ext3defaults0 0

To create the LVM( Logical Volume Manager) we required the disks having ‘8e’ Linux LVM type. First we should create the physical Volume, then we can create the Volume group from disks belongs to physical Volume. lvcreate command is used to create the logical volume on volume group. We can specify the size of logical volume with –L option and name with -n option.

Do the following steps as:

usermod -G training user1

usermod -G training user2

usermod -G training user3

Verify from : cat /etc/group

There are two types of group, I) primary group II) Secondary or supplementary group.

Primary Group: Primary group defines the files/directories and process owner group there can be only one primary group of one user.

Secondary Group is used for permission. Where permission are defined for group members, user can access by belonging to that group.

Here user1, user2 and user3 belong as supplementary to training group. So these users get the permission of group member.

chown or chgrp command is used to change the ownership.

Syntax of chown: chown [-R] username:groupname file/directory

Syntax of chgrp: chgrp [-R] groupname file/directory

Whenever user creates the file or directory, the owner of that file/directory automatically will be that user and that user’s primary group name.

To change group owner ship

chgrp training /data ?Which set the Group Ownership to training

or

chown root.training /data?Which set the user owner to root and group owner to training group.

Verify /data using: ls -ld /data

You will get: drwxr-xr-x 2 root training …………..

Do the following steps as:

1.usermod -G sysadmin john

2.usermod –G sysadmin jane

3.Verify by reading /etc/group file

Using usermod command we can make user belongs to different group. There are two types of group one primary and another is secondary. Primary group can be only one but user can belongs to more than one group as secondary.

usermod -g groupname username?To change the primary group of the user

usermod -G groupname username?To make user belongs to secondary group.

Do the following steps as:

1.echo “1” >/proc/sys/net/ipv4/ip_forward

2.vi /etc/sysctl.conf

net.ipv4.ip_forward = 1

If you want to use the Linux System as a Router to make communication between different networks, you need enable the IP forwarding. To enable on running session just set value 1 to /proc/sys/net/ipv4/ip_forward. As well as automatically turn on the IP forwarding features on next boot set on /etc/sysctl.conf file.

Do the following steps as:

1.lvextend –L+200M /dev/test0/testvolume1

Use lvdisplay /dev/test0/testvolume1)

2.ext2online –d /dev/test0/testvolume1

lvextend command is used the increase the size of Logical Volume. Other command lvresize command also here to resize. And to bring increased size on online we use the ext2online command.

Do the following steps as:

1.dump -0u –f /tmp/back /dev/hda4

dump is the standard backup utility. According to the questions, fullback should take. –0 means fullback, -u means update the /etc/dumpdates which maintains the backup record and -f means filename. If you are directly taking backup into other device, you can specify the device name.

e dump -0u -f /dev/st0 /dev/hda4. Where hda4 is a separate partition mounted on /home.

Questions asking you to install the dialog package from the server. In your Lab FTP server as well as NFS server are configured. You can install either through FTP or NFS.

1.Just Login to server1.example.com through FTP: ftp server1.example.com

2.Enter to pub directory: cd pub

3.Enter to RedHat/RPMS: cd RedHat/RPMS

4.Download the Package: mget dialog-*

5.Logout from the FTP server: bye

6.Install the package: rpm -ivh dialog-*

7.Verify the package either installed or not: rpm -q dialog

Do the following steps as:

1. Insert the CD on CD-ROM and start the system.

2. In Boot: Prompt typelinux askmethod

3. It will display the language, keyboard selection.

4. It will ask you for the installation method.

5. Select the NFS Image from the list

6. It will ask the IP Address, Net mask, Gateway and Name Server. Select Use

Dynamic IP Configuration: because DHCP Server will be configured in your exam lab.

7. It will ask for the NFS Server Name and Redhat Enterprise Linux Directory.

Specify the NFS Server: 172.24.254.254

Directory: /var/ftp/pub

8. After Connecting to the NFS Server Installation start in GUI. Go up to the partition screen by selecting the different Options.

9. Create the partition According to the Question because Size and what-what partition should you create at installation time is specified in your question

10.Create the two RAID partitions having equal size of remaining all free space.

11.Click on RAID button

12.Type mount point /archive

13.Select RAID Level 0

14.Click on ok

15. Then select the MBR Options, time zone and go upto package selections.

It is another Most Important Time of installation. Due to the time limit, you should care about the installation packages. At Exam time you these packages are enough.

X-Window System

GNOME Desktop

(these two packages are generally not required)

Administration Tools.

System Tools

Windows File Server

FTP Servers

Mail Servers

Web Servers

Network Servers

Editors

Text Based Internet

Server Configuration Tools

Printing Supports

When installation will complete, your system will reboot. Jump for another Question.

Do the following steps as:

1.vi /etc/cron.allow

root

or

vi /etc/cron.deny

Write all user name to deny.

/etc/cron.allow, /etc/cron.deny file is used to control users to allow or deny. If /etc/cron.allow file is created only that users are allowed to run cron schedule. Another way to deny to users is /etc/cron.deny write all user name on single line.

Do the following steps as:

1.vi /etc/exports

/data*.example.com(rw,sync)

2.service nfs start

3.service portmap restart

4.chkconfig nfs on

5.chkconfig portmap on

In Linux to share the data we use the /etc/exports file. Pattern is:

Pathclient(permission)

Shared Directory Path, Client can be single host or domain name or ip address. Permission should specify without space with client lists in parentheses. NFS is RPC service so, portmapper service should restart after starting the nfs service.

Do the following steps as:

1.vi /etc/hosts.deny

sshd:ALL EXCEPT .example.com

or

1.vi /etc/hosts.deny

sshd:ALL

2.vi /etc/hosts.allow

sshd:.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/security/access.conf

-:john:LOCAL

2.vi /etc/pam.d/system-auth

accountrequired/lib/security/pam_access.so

/etc/security/access.conf file helps to allow or deny login to users on the basis of origin.

Syntax of /etc/security/access.conf

permission : users : origins

The first field should be a "+" (access granted) or "-" (access denied) character.

The second field should be a list of one or more login names, group names, or ALL (always matches). A pattern of the form user@host is matched when the login name matches the "user" part, and when the "host" part matches the local machine name.

The third field should be a list of one or more tty names (for non-networked logins), host names, domain names (begin with "."), host addresses, internet network numbers (end with "."), ALL (always matches) or LOCAL (matches any string that does not contain a "." character).

In our example denied to john user to login locally.

Do the following steps as:

1.vi /etc/httpd/conf/httpd.conf

<VirtualHost 192.100.0.1>

ServerNamewww.abc.com

DocumentRoot /var/www/abc/

<Directory /var/www/abc>

AllowOverrideauthconfig

</Directory>

DirectoryIndexindex.html

ServerAdminwebmaster@abc.com

ErrorLog logs/error_abc.logs

CustomLog logs/custom_abc.logs common

</VirtualHost>

2.Create the directory and index page on specified path. (Index page can download fromftp://server1.example.comat exam time)

3.vi /var/www/abc/.htaccess

AuthName“Only to Authorized Users”

AuthTypebasic

AuthUserFile/etc/httpd/conf/mypasswd

requirevalid-user

htpasswd –c /etc/httpd/conf/mypasswd user5

htpasswd –m /etc/httpd/conf/mypasswd user6

chgrp apache /etc/httpd/conf/mypasswd

chmod g+r /etc/httpd/conf/mypasswd

service httpd restart

chkconfig httpd on

AllowOverride Authconfig is used to specify which and how much configuration can be overridden by directory specific .htaccess files.

One of the most common tasks performed in users’ .htaccess files is adding authorization. Typically, a user will setup authorization for directories that hold sensitive information with a configuration.

Slave DNS is the backup of master DNS. Automatically within a certain time slave DNS synchronizes with the Master DNS server.

1.vi /etc/named.conf

zone “example.com” IN {

type slave;

masters { 192.100.0.254; };

file “example.com.zone”;

};

named-checkconf command checks the syntax for /etc/named.conf file.

service named start | restart

Do the following steps as:

1.vi /etc/mail/local-host-names

example.com

2.vi /etc/mail/sendmail.mc

dnl # DEAMON_OPTIONS(`Port=smtp,Addr=127.0.0.1,Name=MTA`)dnl

3.m4 /etc/mail/sendmail.mc >/etc/mail/sendmail.cf

4.vi /etc/mail/access

RELAY

example.comRELAY

5.service sendmail start | restart

6.chkconfig dovecot on

7.vi /etc/dovecot.conf

protocols = pop3 pop3s

8.service dovecot start | restart

9.chkconfig dovecot on

/etc/mail/local-host-names file contains the aliases to hostname. Mail server program reads the /etc/mail/sendmail.cf. To change the configuration on mail server, we should edit the /etc/mail/sendmail.mc file and should generate the sendmail.cf using m4 command.

By default sendmail server allows to connect to local host only. So we should edit the /etc/mail/sendmail.mc file to allow connect to other hosts.

By default sendmail server will not forward mail. we should specify on /etc/mail/access to relay or to block mail coming from domain or network or individual email address.

By default dovecot service start only the imap protocol. To start pop protocol with dovecot, we should write in /etc/dovecot.conf file.

Do the following steps as:

1.vi /etc/httpd/conf/httpd.conf

NameVirtualHost 192.100.0.X

<VirtualHostwww.abc.com >

ServerNamewww.abc.com

DocumentRoot /var/www/abc/

DirectoryIndexindex.html

ServerAdminwebmaster@abc.com

ErrorLog logs/error_abc.logs

CustomLog logs/custom_abc.logs common

</VirtualHost>

<VirtualHostwww.example.com >

ServerNamewww.example.com

DocumentRoot /var/www/example/

DirectoryIndexindex.html

ServerAdminwebmaster@example.com

ErrorLog logs/error_example.logs

CustomLog logs/custom_example.logs common

</VirtualHost>

2.Create the directory and index page on specified path. (Index page can download fromftp://server1.example.comat exam time)

3.service httpd start| restart

4.chkconfig httpd on

5.links http://www.abc.com

6.links http://www.example.com

For Name based Virtual Hosting, we should specified the IP address on which we are going to host the multiple sites using NameVirtualHost options.

ServerName means you FQDN, already lookup on DNS

DirectoryRoot path for web documents for this site.

DirectoryIndex default page for websites.

Do the following steps as:

1.vi /etc/squid/squid.conf

#detault:

http_port8080

#Recommended minimum configuration:

# Near the src acl src section

acl allownet src 192.168.0.0/255.255.255.0

acl msnnet dstdomain .msn.com

#Default:

# http_access deny all

#Under Herehttp_access deny msnnet

http_access allow allownet

2.service squid start

3.chkconfig squid on

squid is a proxy caching server, using squid we can share the internet, block the internet, to certain network. First we should define the port for squid, the standard port for squid is 3128. We can run squid on different port by specifying http_port portnumber.

To block or allow the Internet access to hosts, we should create the acl (Access Control List). In this file we can specify only the IP address.

Example: acl aclname src IP/NetmaskAfter creating acl we can block or allow the Internet to specified acl.

http_access allow | deny alcname

Do the following steps as:

Use netconfig command

Enter the IP Address as given station number by your examiner: example: 172.24.0.1

Enter Subnet Mask

Enter Default Gateway and primary name server

press on ok

ifdown eth0

ifup eth0

verify using ifconfig

In the lab server is playing the role of router, IP forwarding is enabled. Just set the Correct IP and gateway, you can ping to 172.25.254.254.

1. vi /etc/resolv.conf

Write : nameserver 192.168.0.254

When root unable to login into the system think:

Is password correct?

Is account expired?

Is terminal Blocked?

Do these Steps:

Boot the System on Single user mode.

Change the password

Check the account expire date by using chage –l root command.

If account is expired, set net expire date: chage –E “NEVER” root

Check the file /etc/securetty?Which file blocked to root login from certain terminal.

If terminal is deleted or commented write new or uncomment.

Reboot the system and login as a root.

Do the following steps as:

1. /proc is the virtual filesystem, we use /proc to modify the kernel parameters at running time.

# echo “1” >/proc/sys/net/ipv4/ip_forward

2. /etc/sysctl.conf?when System Reboot on next time, /etc/rc.d/rc.sysinit scripts reads the file /etc/sysctl.conf. To enable the IP forwarding on next reboot also you need to set the parameter.

net.ipv4.ip_forward=1

Here 0 means disable, 1 means enable.

Do the following steps as:

1.vi /etc/sysconfig/network

GATEWAY=192.168.0.254

OR

vi /etc/sysconf/network-scripts/ifcfg-eth0

DEVICE=eth0

BOOTPROTO=static

ONBOOT=yes

IPADDR=192.168.0.?

NETMASK=255.255.255.0

GATEWAY=192.168.0.254

2.service network restart

Do the following steps as:

Use fdisk /dev/hda?To create new partition.

Type n?For New partitions

It will ask for Logical or Primary Partitions. Press l for logical.

It will ask for the Starting Cylinder: Use the Default by pressing Enter Key.

Type the Size: +100M?You can Specify either Last cylinder of Size here.

Press P to verify the partitions lists and remember the partitions name.

Press w to write on partitions table.

Either Reboot or use partprobe command.

Use mkfs –t ext3 /dev/hda?

Or

mke2fs –j /dev/hda? ?To create ext3 filesystem.

vi /etc/fstab

Write:

/dev/hda?/dataext3defaults0 0

11. Verify by mounting on current Sessions also:

mount /dev/hda? /data

#vi /etc/resolv.conf

nameserver 172.24.254.254

# dig server1.example.com

#host server1.example.com

DNS is the Domain Name System, which maintains a database that can help your computer translate domain names such as www.redhat.com to IP addresses such as 216.148.218.197. As no individual DNS server is large enough to keep a database for the entire Internet, they can refer requests to other DNS servers.

DNS is based on thenameddaemon, which is built on the BIND (Berkeley Internet Name Domain) package developed through the Internet Software Consortium

Users wants to access by name so DNS will interpret the name into ip address. You need to specify the Address if DNS server in each and every client machine. In Redhat Enterprise Linux, you need to specify the DNS server into /etc/resolv.conf file.

After Specifying the DNS server address, you can verify using host, dig and nslookup commands.

This is boot related problem. There will be same questions repeated two times but problem is different.

First When you restart the system you will get the Error:

File Not Found

mount: error 15 mounting ext3

mount: error 2 mounting none

switchroot: mount failed: 22

umount /initrd/dev/: 2

Kernel Panic: no syncing: Attempted to kill init !

This error occurred in your system before showing welcome redhat linux. That means problem in grub boot loader.

Restart the System

Check the grub boot loader configuration by pressing e shortcut key.

You will see like:

root (hd0,0)

kernel /vmlinuz-2.6.9-5.EL ro root= / rhgb quiet

initrd /initrd-2.6.9-5.EL.img

OR

root (hd0,0)

kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/root rhgb quiet

initrd /initrd-2.6.9-5.EL.img

Then Edit Boot loader to make like

root (hd0,0)

kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/ rhgb quiet

initrd /initrd-2.6.9-5.EL.img

Check all lines and edit as same as above. Press b to boot the system

After booting the system you should correct the /etc/grub.conf file.

If still you are getting Error likeFile not found, it seems that either kernel file or initrd file is missing. To troubleshoot with these problem, boot the system on rescue mode.

linux rescue

chroot /mnt/sysimage

Check the files on /boot, if not available install the kernel package from ftp or nfs server

Create the initrd image file on boot using: mkinitrd initrd-2.6.9-5.EL.img `uname –r`

It is due to either default runlevel or runlevel specific scripts.

id:?:initdefault:?Where default runlevel is specified. It shouldn’t be 6.

l3:3:wait:/etc/rc.d/rc 6?It reads the scripts of runlevel 6 while booting system on rulevel 3.

It should be like:

si::sysinit:/etc/rc.d/rc.sysinit

l0:0:wait:/etc/rc.d/rc 0

l1:1:wait:/etc/rc.d/rc 1

l2:2:wait:/etc/rc.d/rc 2

l3:3:wait:/etc/rc.d/rc 3 Should be like this

l4:4:wait:/etc/rc.d/rc 4

l5:5:wait:/etc/rc.d/rc 5

l6:6:wait:/etc/rc.d/rc 6

Do the following steps as:

Use fdisk /dev/hda?To create new partition.

Type n?For New partitions

It will ask for Logical or Primary Partitions. Press l for logical.

It will ask for the Starting Cylinder: Use the Default by pressing Enter Key.

Type the Size: +100M?You can Specify either Last cylinder of Size here.

Press P to verify the partitions lists and remember the partitions name.

Press w to write on partitions table.

Either Reboot or use partprobe command.

Use mkfs –t ext3 /dev/hda?

Or

mke2fs –j /dev/hda? ?To create ext3 filesystem.

vi /etc/fstab

Write:

/dev/hda?/dataext3defaults0 0

Verify by mounting on current Sessions also:

mount /dev/hda? /data

Do the following steps as:

vi /etc/resolv.conf

nameserver 172.24.254.254

host server1.example.com

On every clients, DNS server is specified in /etc/resolv.conf. When you request by name it tries to resolve from DNS server.

By Default system accept the logs only generated from local host. To accept the Log from other host configure:

vi /etc/sysconfig/syslog

SYSLOGD_OPTIONS="-m 0 -r"

Where

-m 0 disables 'MARK' messages.

-r enables logging from remote machines

-x disables DNS lookups on messages recieved with -r

service syslog restart