RedHat RH302 RHCE (Redhat Certified Engineer) Exam Practice Test

Do the following steps as:

1. use the authconfig --nisserver=192.168.0.254 --nisdomain=rhce.com --update or system-config-authentication

2. Click on Enable NIS

3. Type the NIS Domain: rhce.com

4. Type Server 192.168.0.254 then click on next and ok

5. You will get a ok message.

6. vi /etc/auto.master and write at the end of file

/home/stationx /etc/auto.home --timeout=60

7. vi /etc/auto.home and write

*-rw,soft,intr192.168.0.254:/home/stationx/&

Note: please specify your station number in the place of x.

8. Service autofs restart

9. Login as the rhce1 or rhce2 or rhce3 on another terminal will be

Success.

According to question, rhce.com domain is already configured. We have to make a client of rhce.com domain and automatically mount the home directory on every client. To make a member of domain, we use the autheconfig or system-config-authentication command. There a are lots of authentication server i.e NIS, LDAB, SMB etc. NIS is a RPC related Services, no need to configure the DNS, we should specify the NIS server address.

Here Automount feature is available. When user tried to login, home directory will automatically mount. The automount service reads the configuration from /etc/auto.master file.

On /etc/auto.master file we specified the mount point the configuration file for mount point.

Do the following steps as:

useradd user1

useradd user2

useradd user3

passwd user1

passwd user2

passwd user3

We create the user using useradd command and we change the password of user using passwd command. If you want to set the blank password use: passwd -d username.

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.

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.

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.

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.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.chmod g+s /storage

2.Verify using: ls -ld /storage

Permission should be like:

drwxrws--- 2 root sysusers 4096 Mar 16 18:08 /storage

If SGID bit is set on directory then who every users creates the files on directory group owner automatically the owner of parent directory.

To set the SGID bit: chmod g+s directory

To Remove the SGID bit: chmod g-s directory

Do the following steps as:

1. use the authconfig --nisserver= --nisdomain= --update

Example: # authconfig --nisserver=192.168.0.254 --nisdomain=RHCE --update

or system-config-authentication

2. Click on Enable NIS

3. Type the NIS Domain: RHCE

4. Type Server 192.168.0.254 then click on next and ok

5. You will get a ok message.

6. Create a Directory /rhome/stationx where x is your station number.

6. vi /etc/auto.master and write at the end of file

/rhome/stationx /etc/auto.home --timeout=60

7. vi /etc/auto.home and write

*-rw,soft,intr192.168.0.254:/rhome/stationx/&

Note: please specify your station number in the place of x.

8. Service autofs restart

9. Login as the nisuser2001 or nisuser2002 on another terminal will be

Success.

According to question, RHCE domain is already configured. We have to make a client of RHCE domain and automatically mount the home directory on your system. To make a member of domain, we use the authconfig with option or system-config-authentication command. There a are lots of authentication server i.e NIS, LDAB, SMB etc. NIS is aRPC related Services, no need to configure the DNS, we should specify the NIS server address.

Here Automount feature is available. When user tried to login, home directory will automatically mount. The automount service used the /etc/auto.master file. On /etc/auto.master file we specified the mount point the configuration file for mount point.

Do the following steps as:

1.chmod g+s /archive

2.Verify using: ls -ld /archive

Permission should be like:

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

If SGID bit is set on directory then who every users creates the files on directory group owner automatically the owner of parent directory.

To set the SGID bit: chmod g+s directory

To Remove the SGID bit: chmod g-s directory

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.iptables –t filter –A INPUT –s ! 192.168.0.0/24 –p tcp –d 192.168.0.254 --dport 20 –j DROP

2.iptables –t filter –A INPUT –s ! 192.168.0.0/24 –p tcp –d 192.168.0.254 --dport 21 –j DROP

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.

Here your Local LAN means your domain named example.com.

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

192.168.0RELAY

5.service sendmail start | restart

6.chkconfig sendmail 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.

7.vi /etc/aliases

john:jane

8.newaliases

We can redirect the mail of one user to another user using /etc/aliases file. In example all mail of john goes to jane user.

Do the following steps as:

1.ftp ftp://server1.example.com

2.Login as an anonymous and download the file.

3.Copy the file in /var/www/html if you downloaded in another location.

4.service httpd restart

5.Test using links: links http://station?.example.com

Note: In examination Lab DNS will configure for every stations.

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/samba/smb.conf

[global]

netbios name=station?

workgroup = mygroup

server string=Share from Linux Server

security=user

smb passwd file=/etc/samba/smbpasswd

encrypt passwords=yes

[data]

path=/data

writable=no

public=no

browsable=yes

write list= user1 user2

2.smbpasswd –a user1

3.smbpasswd –a user2

……..

4.service smb start | restart

5.chkconfig smb on

Samba servers helps to share the data between linux and windows. Configuration file is /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 list option 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

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/httpd/conf/httpd.conf

<VirtualHost 192.168.0.?>

ServerNamestation?.example.com

DocumentRoot /var/www/station?

DirectoryIndexindex.html

ServerAdminwebmaster@example.com

</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

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.

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:

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.

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:

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.

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!)

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

After completing the Boot loader problem, you will boot the system, but it goes to emergency mode. Remember that if System boots on Emergency mode that means file system problem.

You will get the Shell, remount the / filesystem with read and write mode.

1.First Find out the / filesystem using e2lable /dev/hda1, e2lable /dev/hda2 etc

2.mount –o remount,defaults /dev/hda? /

3.vi /etc/fstab

You will get like:

/root/ext3defaults 1 1

or //rootext3defaults 1 1

4.Edit the file like:

//ext3defaults 1 1

5.Configure the /etc/grub.conf file if just booting system by editing grub from grub prompt.

6.Reboot the system.

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

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? Where ? is your partition number

Or

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

mkdir /mnt/neo

vi /etc/fstab

Write:

/dev/hda?/mnt/neoext3defaults1 2

Verify by mounting on current Sessions also:

mount /dev/hda? /mnt/neo

#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 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.

Do the following steps as:

Think while Problems occurred on booting System on Runlevel 5 (X Window).

/tmp is full or not

Quota is already reached

Video card or resolution or monitor is misconfigured.

xfs service is running or not.

Do These:

1.df –h /tmp/tmp is full remove the unnecessary file

quota usernameif quota is already reached remove unnecessary file from home directory.

Boot the System in runlevel 3.you can pass the Kernel Argument from boot loader.

Use command: system-config-displayIt will display a dialog to configure the monitor, Video card, resolution etc.

Set the Default Runlevel 5 in /etc/inittab

id:5:initdefault:

6.Reboot the System you will get the GUI login Screen.

Do the following steps as:

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

DEVICE=eth0

BOOTPROTO=static

ONBOOT=yes

IPADDR=x.x.x.x

NETMASK=x.x.x.x

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.

Do the following steps as:

1. Use fdisk /dev/hdaTo create new partition.

Type nFor New partition

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. Default System ID is 83 that means Linux Native.

Type t to change the System ID of partition.

Type Partition Number

Type 82 that means Linux Swap.

Press w to write on partitions table.

Either Reboot or use partprobe command.

mkswap /dev/hda?To create Swap File system on partition.

swapon /dev/hda?To enable the Swap space from partition.

free –mVerify Either Swap is enabled or not.

vi /etc/fstab

/dev/hda?swapswapdefaults0 0

Reboot the System and verify that swap is automatically enabled or not.

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.

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:

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

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.

Do the following steps as:

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

vi /etc/sysctl.conf

net.ipv4.ip_forward=1

/proc is the virtual filesystem, containing the information about the running kernel. To change the parameter of running kernel you should modify on /proc. From Next reboot the system, kernel will take the value from /etc/sysctl.conf.

Do the following steps as:

1.vi/var/named/chroot/etc/named.conf

acl localnet { 192.168.0.0/24; };

options {

allow-query { localnet; };

};

2.service named restart | start

allow-query is a global option on/var/named/chroot/etc/named.conf, specifies an address match list of hosts allowed to query this server. If this option is not set, any host can query the server.

Do the following steps as:

1.vi /etc/exports

/local*.example.com(rw,sync) trusted.cracker.org(ro,sync)

Check the SELinux Context, should be like this:

-rw-r--r-- root root system_u:object_r:exports_t /etc/exports

Use the restorecon –R /etc command to restore the selinux context of the file.

service nfs start | restart

service portmap start | restart

chkconfig nfs on

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. We can specify multiple clients’ list separating by space with different shared option.

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.

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

1.vi /var/named/chroot/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 /var/named/chroot/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

192.168.0RELAY

@cracker.orgREJECT

5.service sendmail start | restart

6.chkconfig dovecot on

7.vi /etc/dovecot.conf

protocols = pop3 pop3s imap imaps

8.service dovecot start | restart

9.chkconfig dovecot on

10.vi /etc/aliases

user5:user2

11.newaliases

/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.

Using /etc/aliases file we can map the user name to send mail of one user to another user. To rebuild database we use the newaliases command.

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/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:

vi /etc/mail/virtusertable

@my133t.orgmarion

# service sendmail restart

/etc/mail/virtusertable file is used to send the mail coming for virtual user to real user. According to question, all mail to cracker.org should get by eric user so

@my133t.orgeric : Which sends all mail of cracker.org to eric user.

Do the following steps as:

1.vi /etc/hosts.deny

nfs,portmap:ALL EXCEPT .example.com, 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.rpm -ivh ftp://server1.example.com/pub/updates/kernel-2.6.9-11.i686.rpm

2.vi /etc/grub.conf

default=1Change this value to 1

timeout=5

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

hiddenmenu

title Red Hat Enterprise Linux ES (2.6.9-11)

root (hd0,0)

kernel /vmlinuz-2.6.9-11.EL ro root=LABEL=/ rhgb quiet

initrd /initrd-2.6.9-11.EL.img

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

According question that kernel is available to anonymous user. You can directly install from the ftp server using rpm command.

When you install the kernel, it will write on /etc/grub.conf file. You can set the default kernel by changing the default value. See on the output of /etc/grub.conf file that new kernel is on first title so it’s index is 0 and previous kernel’s index is 1.

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:

vi /etc/auto.master

/mnt/etc/auto.misc--timeout=50

vi /etc/auto.misc

data-rw,soft,intrserver1.example.com:/data

service autofs restart

chkconfig autofs on

When you mount the other filesystem, you should unmount the mounted filesystem, Automount feature of linux helps to mount at access time and after certain seconds, when user unaccess the mounted directory, automatically unmount the filesystem.

/etc/auto.master is the master configuration file for autofs service. When you startthe service, it reads the mount point as defined in /etc/auto.master.

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.