Answer Posted / bharath

1. Where the History file can be located?
A. the file .bash_profile stored in home directory of user.
To see that file vi .bash_profile and edit it.
2. How will you harden the server?
A. A Server-- it is weather in testing or production-- are primary targets for
the attackers. By taking the proper steps, you can turn a vulnerable box into
a hardened server.
How to secure SSH sessions, configure firewall rules, minimize software, listed below,
1. Encrypt Data communication
-- use scp, ssh avoid FTP, Telnet and Rlogin /rsh
2. Minimize Software to minimize vulnerability
-- use RPM pkg management / YUM utility to remove unwanted packages installed
3. One Network Service per System or Vm Instance
-- Run different network services on separate servers or vm instance.
For example, if an attacker able to successfully exploit software called
Apache flow, he/she get an access to entire server including other services
such as MYSQL, email server and so on.
4. Keep linux software and Kernel up to date.
-- Use yum update or up2date
some distros apt-get update
5. Security essentials like selinux
6. password authentication like password aging, restricting to user previous
passphrases, and locking user accounts after login failures.
7. Disable unwanted services using chkconfig --list | grep "3:on"

and many more. . .

3. Diff between Raid 1 and Raid 5?
A. RAID 1 is disk striping. no mirroring no parity. Minimum 2 disks required. If any
One disk fails all the data get lost.
RAID 5 is disk striping with parity. Minimum 3 disks required. if anyone disk fails
Data is safe, if two fails data get lost.

4. What is the largest disk size can be used in LVM?
A. Don't know exactly, think of 2TB or 8TB (Warning- Not genuine answer)

5. How will you remove a PV from lvm without any data loss?
A. by using pvremove command.

6. What is the diff between ext3 and ext2 File system?
A. ext3 is also same as the ext2, but journaling concept is introduced in ext3.
Compared to ext2, ext3 is slow. ext2 less secure compared to ext3. ext2 is less
Performance where as ext3 is very good performance.


7. How we can use resize2fs, what is the purpose?
A. resize2fs is only for ext2 filesystem but not ext3.
first unmount the partition
#umount /dev/sda1

#tune2fs -O ^has_journal /dev/sda1 #to remove journal from /dev/sda1

#e2fsck -f /dev/sda1

#resize2fs /dev/sda1 600M #resize the partition


8. What is the purpose of LVM? Why it is used?


9. If the FS is in read-only mode, so we cannot create any
file. How will you fix it?
A. LVM is a mechanism use for providing specality of extending (or) reducing
the sizes of an existing partition.


10. How to create swap partition after OS installation?
A. swap can be created in two ways after the installation,
1. fdisk command
2. create a swap file using dd command

after creating swap file or file system

#mkswap /dev/sda10
#swapon /dev/sda10
#swapon -s #To see the swap devices

by using dd command

#dd if=/dev/zero of=/swap bs=1024 count=1

Which will creates the file size 1024(1GB).

#mkswap /swap
#swapon /swap
#swapon -s #to see the swap devices


11. What is the diff between ssh and telnet?
A. ssh is secured shell, allows the user to login remotely with more secured.
whereas telnet also same but authentications like passwords, transfers over a network
as text mode. so it is not good to use.

12. How to find out the dependency required for a package?
#rpm -qpR filename.rpm

Lists the dependency list of packages.

What are system calls used for process management in linux?

583

what are different ways the context switch happens from user to kernel space or vice-versa ?

2138

Explain process management system calls in linux?

544

I would like to know whether Simado and Setu products are they EPBX or not ?

1926