How to Open 7zip Files Under Ubuntu

Step 1 : Install application

#sudo apt-get install p7zip

Step 2 : Exectute this command

#p7zip -d filename.7z

Setup SAMBA server on Ubuntu

Step 1: Installation

#apt-get install samba

Step 2: Configuration

Configuration file : /etc/samba/smb.conf

• Edit below section

Workgroup = EXAMPLE

…………

Security = user

• Create a new section at the bottom of the file /etc/samba/smb.conf

[Samba Share]

Comment= Samba  File Server Share

Path=/path to directory

Browsable = yes

Guest ok = yes

Read only = no

Create mask = 0755

Step 3: Create directory and change permissions

#mkdir /path to directoy

#chown  -R nobody:nobody /path to directory

Step 4 : Restart Samba service

#/etc/init.d/samba restart

Enjoy!!!!!!!!!!!!

Open ports using IPTABLES

If you want your machine to respond to requests initiated from elsewhere on the internet you need to open the required ports. You need to know below details first:

1. Service name you want to open up
2. Is it a tcp or udp service?
3. Port number(s) uses by service?

Example:

To enable ssh access to your box from anywhere on for Class A networks, you could use something like

iptables -A allowed -p tcp --dport 22 -s 10.2.0.0/16 -j ACCEPT
iptables -A allowed -p udp --dport 22 -s 10.2.0.0/16 -j ACCEPT

iptables -A allowed -p tcp --dport 22 -s 10.8.0.0/16 -j ACCEPT
iptables -A allowed -p udp --dport 22 -s 10.8.0.0/16 -j ACCEPT

This allows both udp and tcp traffic from either of the two class A networks to access port 22 on your machine.

Work with tcpwrappers hosts.deny and hosts.allow

You can use tcpwrappers to Block user,ip,daemon from outside or your inside newwork. For allow use host.allow file and to block use host.deny file.

Step 1. Use your favorite editor like vi.

Step 2. Type vi /etc/hosts.deny
Step 3. At the bottom line just type “ALL:ALL:deny” to restricted all of daemon process
Step 4. Save it.
Step 5. Open “/etc/hosts.allow” with vi editor
Step 6. At the buttom line “ALL :(some ip that you allow):allow” to allow anything from my IP address
Step 7. Save it.

Working with tar and tar Encryption

STEP 1 :  (Using the tar command on the directory /example)

Suppose you have a directory /stuff. To tar everything in stuff to create a “.tar” file.

# tar -cvf example.tar example

It will create example.tar file.

STEP 2 :  (Using the tar command to create a “.tar.gz” of /example)

# tar -czf example.tar.gz example

STEP 3 :  (List the files in the archive)

# tar -tzf example.tar.gz
or
# tar -tf example.tar

STEP 4 :   (ENCRYPTION)

# tar -zcvf – example | openssl des3 -salt -k secretpassword | dd of=example.des3

This will create example.des3…Please don’t forget the password you put in place of secretpassword.

If you want to do this interactively then

# dd if=example.des3 |openssl des3 -d -k secretpassword|tar zxf -

Multiple IP address on Single NIC (Redhat/Fedora)

We can setup two Ipaddress on single NIC.

Below i have mentioned for Redhat/Fedora/CentOs system.

STEP 1 : (Initial/First IP address)

#cat /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0
BOOTPROTO=static
BROADCAST=10.8.0.255
IPADDR=10.8.0.10
NETMASK=255.255.255.0
NETWORK=10.8.0.0
ONBOOT=yes

STEP 2 : (Second IP address)
#cat /etc/sysconfig/network-scripts/ifcfg-eth0:1

DEVICE=eth0:1
BOOTPROTO=static
BROADCAST=10.8.0.255
IPADDR=10.8.0.11
NETMASK=255.255.255.0
NETWORK=10.8.0.0
ONBOOT=yes

View Routing Table and Change your default Gateway

The netstat -nr command will provide the contents of the touting table.

# netstat -nr



Kernel IP routing table

Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface

10.8.0.0        0.0.0.0         255.255.255.0   U         0 0          0 eth0

169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0

0.0.0.0         10.8.0.1        0.0.0.0         UG        0 0          0 eth0



Change Your Default Gateway

You will need to update your /etc/sysconfig/network file to reflect the change. This file is used to configure your default gateway

NETWORKING=yes
HOSTNAME=newhost
GATEWAY=10.8.0.2

Use of Netstat Commands

Netstat (network statistics) is a command-line tool that displays network connections (both incoming and outgoing), routing tables, and a number of network interface statistics. Netstat is a useful tool for checking your network configuration and activity.

Check tcp connection established on your machine using below command

1: netstat --tcp

% netstat --tcp --numeric
Active Internet connections (w/o servers)

Proto Recv-Q Send-Q Local Address           Foreign Address         State

tcp        0      0 nexubuntu:ldap          nexubuntu:38885         ESTABLISHED

tcp        0      0 nexubuntu:38885         nexubuntu:ldap          ESTABLISHED

tcp        0      0 nexubuntu:ssh           10.8.0.151:50776        ESTABLISHED

tcp        0      0 nexubuntu:microsoft-ds  nexubuntu:59000         ESTABLISHED

tcp        0      0 nexubuntu:38875         nexubuntu:ldap          ESTABLISHED

tcp        0      0 nexubuntu:ldap          nexubuntu:52342         ESTABLISHED

tcp        0      0 nexubuntu:ssh           10.8.0.151:50775        ESTABLISHED

tcp      244      0 nexubuntu:59004         nexubuntu:microsoft-ds  ESTABLISHED

tcp      244      0 nexubuntu:59000         nexubuntu:microsoft-ds  ESTABLISHED

tcp        0      0 nexubuntu:ldap          nexubuntu:38875         ESTABLISHED

tcp        0      0 nexubuntu:microsoft-ds  nexubuntu:59004         ESTABLISHED

tcp        0      0 nexubuntu:52343         nexubuntu:ldap          TIME_WAIT

tcp        0      0 nexubuntu:52342         nexubuntu:ldap          ESTABLISHED

tcp        0      0 nexubuntu:microsoft-ds  nexubuntu:58998         ESTABLISHED

tcp      244      0 nexubuntu:58998         nexubuntu:microsoft-ds  ESTABLISHED

If you want to see what (TCP) ports your machine is listening on, use netstat --tcp --listening. Another useful flag to add to this is --programs which indicates which process is listening on the specified port.

2: netstat --tcp --listening --programs

# sudo netstat --tcp --listening --programs
Active Internet connections (only servers)

Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name

tcp        0      0 *:nfs                   *:*                     LISTEN      -

tcp        0      0 *:ldap                  *:*                     LISTEN      2715/slapd

tcp        0      0 *:ftp                   *:*                     LISTEN      3302/vsftpd

tcp        0      0 *:ssh                   *:*                     LISTEN      4022/sshd

tcp        0      0 nexubuntu:postgresql    *:*                     LISTEN      2680/postgres

tcp        0      0 *:smtp                  *:*                     LISTEN      3259/master

tcp        0      0 *:58777                 *:*                     LISTEN      2098/rpc.statd

tcp        0      0 *:microsoft-ds          *:*                     LISTEN      3283/smbd

tcp6       0      0 [::]:ldap               [::]:*                  LISTEN      2715/slapd

tcp6       0      0 [::]:www                [::]:*                  LISTEN      3750/apache2

Uses netstat --route to display the routing table.

3: netstat --route

% netstat --route
Kernel IP routing table

Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface

10.8.0.0        *               255.255.255.0   U         0 0          0 eth0

link-local      *               255.255.0.0     U         0 0          0 eth0

default         mygateway1.ar7  0.0.0.0         UG        0 0          0 eth0

Uses the --statistics flag to display networking statistics.

Using this flag by itself displays all IP, TCP, UDP, and ICMP connection statistics.

4: netstat --statistics --route

Network configuration for Debian

Ip from dhcp

#/etc/network/interfaces
# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet dhcp

For a static IP

#/etc/network/interfaces
# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
address 10.8.0.100
netmask 255.255.255.0
gateway 10.8.0.1
broadcast 10.8.0.255

How to add multiple IP addresses manually

# ifconfig

will output all the configured addresses

eth0: inet addr:10.8.0.10 Bcast:10.8.0.255 Mask:255.255.255.0

To add on extra IP addresses execute below command:

# ifconfig eth0:1 10.8.0.12 netmask 255.255.255.0

For additional IP addresses, make sure you increment the 1 in eth0:1

Third ip address would be like this

# ifconfig eth0:2 10.8.0.13 netmask 255.255.255.0

How to add multiple IP addresses manually?

Assigning a virtual IP to a NIC

Assigning a virtual IP to a NIC is a very easy task either you use the system-config-network tool or just do some text file editing. The script ifconfig can also be used to create a virtual network interface, but this would not be permanent since the changes ifconfig makes do not survive a reboot.

In Fedora, all information about the network interfaces is kept in the following directories:

• /etc/sysconfig/network-scripts/


• /etc/sysconfig/networking/

My NIC configuration script is /etc/sysconfig/network-scripts/ifcfg-eth0 looks like this:

DEVICE=eth0

BOOTPROTO=static

BROADCAST=192.168.0.255

HWADDR=00:00:00:00:00:00

IPADDR=192.168.0.1

NETMASK=255.255.255.0

NETWORK=192.168.0.0

ONBOOT=yes

TYPE=Ethernet

GATEWAY=192.168.0.254

Make a copy of this in the same directory naming the new file ifcfg-eth0:1

# cp ifcfg-eth0 ifcfg-eth0\:1

Modification in file ifcfg-eth0\:1 is shown in bold

DEVICE=eth0:1

BOOTPROTO=static

BROADCAST=192.168.0.255

HWADDR=00:00:00:00:00:00

IPADDR=192.168.0.101

NETMASK=255.255.255.0

NETWORK=192.168.0.0

ONBOOT=yes

TYPE=Ethernet

GATEWAY=192.168.0.254

So, its IP address will be 192.168.0.101. Save the file and copy it to/etc/sysconfig/networking/devices/:

# cp ifcfg-eth0\:1 /etc/sysconfig/networking/devices/

Also, copy it to your default network profile or whichever profile you use:

# cp ifcfg-eth0\:1 /etc/sysconfig/networking/profiles/default/

Now, bring up the new interface using the ifup script:

# ifup eth0\:1

Running ifconfig, the new interface should be listed. You can also check it by pinging:

# ping 192.168.0.101

Commands related to Process Control

Here "PID" is refer to the process ID, that you can get from command "ps -aux"

#fg PID
It Brings a background or stopped process to the foreground.

#bg PID
It sends the process to the background.

#any command &
Run any command in the background (the symbol "&" means "run the proceeding command in the background").

#batch any command
Run any command when the system load is low. I can logout and the process will keep running.

#at 18:00
Execute a command at a specified time. You will be prompted for the command(s) to run, until you press d.

#kill PID
To shutdown process by force. First determine the PID of the process to kill using ps.

#killall program name
Kill program(s) by name.

#nice program_name
Run program name adjusting its priority. The priority value may be in the range -20 to 19. Only root may specify negative values. Use "top" to display the priorities of the running processes.

#renice -1 PID
(as root) Change the priority of a running process to -1. Normal users can only adjust processes they own, and only up from the current value (make them run slower).

Useful commands for Ubuntu

Privileges Commands

sudo command - run command as root
sudo su – root shell open
sudo su user – open shell as a user
sudo -k – forget your password sudo
gksudo command – sudo visual dialog (GNOME)
kdesudo command – sudo visual dialog (KDE)
sudo visudo – edit / etc / sudoers
gksudo nautilus – root file manager (GNOME)
kdesudo konqueror – root file manager (KDE)
passwd – change your password

Network Commands

ifconfig – displays information network
iwconfig – displays information from wireless
sudo iwlist scan – scan wireless networks
sudo /etc/init.d/networking restart – reset the network
(file) /etc/network/interfaces – manual configuration
ifup interface – bring online interface
ifdown interface – disable interface

Display Commands

sudo /etc/init.d/gdm restart – reset X (Gnome)
sudo /etc/init.d/kdm restart – reset X (KDE)
(file) /etc/X11/xorg.conf – show Configuration
sudo dpkg-reconfigure - reconfigure xserver-xorg-phigh - reset configuration X
Ctrl+Alt+Bksp – X display reset if frozen
Ctrl+Alt+FN – switch to tty N
Ctrl+Alt+F7 – switch back to X display

Service System Commands.

start service – service to start work (Upstart)
stop service – service to stop working (Upstart)
status service – check if service is running (Upstart)
/etc/init.d/service start – start service (SysV)
/etc/init.d/service stop – stop service (SysV)
/etc/init.d/service status – check service (SysV)
/etc/init.d/service restart – reset service (SysV)
runlevel – get current runlevel

Firewall related commands

ufw enable – turn on the firewall
ufw disable – turn off the firewall
ufw default allow – allow all connections by default
ufw default deny – drop all connections by default
ufw status – current rules and
ufw allow port – to allow traffic on port
ufw deny port – port block
ufw deny from ip – ip block

System Commands.

lsb_release -a – get the version of Ubuntu
uname -r – get kernel version
uname -a – get all the information kernel

Commands for Package Manager.

apt-get update – refresh updates available
apt-get upgrade – update all packages
apt-get dist-upgrade – version update
apt-get install pkg – installing pkg
apt-get remove pkg – uninstall pkg
apt-get autoremove – removing packages obsotletos
apt-get -f install – try to fix packages
dpkg –configure -a – try to fix a broken package
dpkg -i pkg.deb – install file pkg.deb
(file) /etc/apt/sources.list – list of repositories APT

Commands Special Packages.

ubuntu-desktop – Setting the standard Ubuntu
kubuntu-desktop – KDE Desktop
xubuntu-desktop – desktop XFCE
ubuntu-minimal – core earnings Ubuntu
ubuntu-standard – the standard utilities Ubuntu
ubuntu-restricted-extras – not free, but useful
kubuntu-restricted-extras – ditto KDE
xubuntu-restricted-extras – ditto XFCE
build-essential – packages used to compile
linux-image-generic – latest generic kernel image
linux-headers-generic – latest headlines

Applications commands.

nautilus – File Manager (GNOME)
dolphin – File Manager (KDE)
konqueror – Web browser (KDE)
kate – text editor (KDE)
gedit – text editor (GNOME)

Useful 100+ Linux commands

1. Schedule a queue to run at 9am on March 1st. Note: Ctrl-d to save and exit.

# at 9am March 1

2. Schedule a queue to run after 5 minutes.

# at now +5 minutes

3. Check any jobs pending to run, same as at -l .

# atq

4. Empty out a file.

# cat /dev/null > /path/to/file

5. Change directory, see also pushd and popd.

# cd

6. List run level information for the service type.

# chkconfig --list

7. Change owner recursively.

# chown -R : /path/to/directory

8. Change shell.

# chsh

9. Scan recursively for viruses.

# clamscan -r

10. Compare two files.

# cmp file1 file2

11. Copy keeping the directory structure.

# cp --parent /source/path /destination/path

12. Copy keeping the permissions of the user.

# cp -p

13. Copy recursive.

# cp -r

14. Copy without shell aliasing.

# \cp

15. List crontab for user.

# crontab -u -l

16. Check current date and time.

# date

17. Set current date and time, may need to set the hardware clock to the system time too, `man hwclock`.

# date -s 'Wed May 28 11:35:00 EST 2003'

18. Show disk free in human readable format.

# df -h

19. Configure interface using DHCP protocol.

# dhclient eth0

20. Find context differences between two files.

# diff -c

21. Creating a patch file.

# diff -Naur oldDir/oldFile newDir/newFile > new_patchFile

22. Kernel buffer

# dmesg

23. Show disk used in human readable format.

# du -h /path/to/directory

24. Find files larger than 10MB.

# find /path/to/file -size +10000k

25. Find file permissions with setuids.

find / \( -perm -4000 -o -perm -2000 \) -exec ls -ldb {} \;>> /tmp/suids

26. Search for world writable files and directories.

# find / -perm -002

27. Display information on free and used memory.

# free

28. Grep on word boundaries.

grep -w

29. Count the number of mathces - similar to “wc -l”.

# grep -c

30. Perform timings of device reads for benchmark and comparison purposes.

# hdparm -t /dev/hda1

31. Set the hardware clock to the current system time.

# hwclock --systohc

32. check the ip address

# ifconfig

33. Add an  ip address to eth0.

# ifconfig eth0:x xxx.xxx.xxx.xxx

34. Install loadable kernel module. You can also use `modprobe` to do the same.

# insmod

35. Displays information about your system’s CPU and I/O.

# iostat [ interval [ count ] ]

36. List iptables firewall rules in numeric format.

# iptables -L -n

37. HangUP process so it will re-read the config file.

# killall -HUP

38. Install the boot loader and increase verborsity.

# lilo -v -v

39. Query the boot map.

# lilo -q

40. One time boot to the named kernel.

# lilo -R

41. Create symbolic link to the target file or directory.

# ln -s

42. Configure dynamic linker run-time bindings

# ldconfig

43. List the IPs bound via Ensim

# listaliases

44. Quickly search for indexed files. Run `updatedb` to update the indexed database.

# locate

45. List files.

# ls

46. List loaded kernel modules

# lsmod

47. Create the access.db file database map for sendmail.

# makemap hash /etc/mail/access.db < /etc/mail/access

48. Create/Make a new directory.

# mkdir

49. Generate a random 128 character length password.

# mkpasswd -l 128

50. Read in the contents of your mbox (or the specified file).

# mail -f /var/mail/nameOfFile

51. Print the mail queue

# mailq

52.

# mailstat /path/to/procmail/log

53. Description of the hierarchy directory structure of the system

# man hier

54. Check the MD5 message digest.

# md5sum

55. Mount points check.

# mount

56. Provide information about your systems’ processor.

# mpstat [ interval [ count ] ]

57.

# ncftpget -R -u  -p
hostname /local_dir /remote_dir

58.

# netstat -a | grep -i listen

59. Will show you who is attached to what port.

# netstat -anpe

60.

# netstat -n

61. See which programs are listening on which port

# netstat -lnp

62. Will show you what local TCP ports are open and what programs are running on them.

# netstat -lntpe

63. Will show you what local UDP ports are open and what programs are running on them.

# netstat -lnupe

64. Run a program with modified scheduling priority. (# range between -20 to +20, negative is higher priority)

# nice -n # [command to nice]

65. Scan network

# nmap -v hostname/ip

66. Patch and keep a backup

# patch -p# -b < patch_file

67.

# ps -ecaux

68. Turn off all quotas for users and groups, verbose mode

# quotaoff -augv

69. Check quota for all users and groups interactively, do quotaoff first.

# quotacheck -augmiv

70. Turn on all quotas for users and groups

# quotaon -augv

71. Add host ip to route on a particular device.

# route add -host xxx.xxx.xxx.xxx dev eth0:x

72.

# rdate

73. Remove file

# rm

74. Remove kernel module

# rmmod

75. Display the routing table in numeric.

# route -n

76.

# rpm

77. Uninstall/erase package.

# rpm -e

78. Erase without dependency check.

# rpm -e --nodeps

79. List out installed rpms by date, latest on top.

# rpm -qa --last | less

80. Rebuild rpm database.

# rpm --rebuilddb

81. Find which package owns the file.

# rpm -qf /path/to/file
# rpm -q --whatprovides /path/to/file

82. Verify package.

# rpm -V

or

# rpm -Vf /path/to/file

83. Locate documentation for the package that owns the file.

# rpm -qdf /path/to/file

84. Query information on package.

# rpm -qip

85. Query files installed by package.

# rpm -qlp

86. Gives list of files that will be installed/overwritten.

# rpm -ql

87. Will show the scripts that will be executed.

# rpm -q --scripts

88. Display system activity information

# sar

89. Print a 0 padded sequence of numbers.

# seq -w 1 10

90. Record eveything printed on your terminal screen.

# script -a

Ctrl+D to exit out. `more ` to view.

91. Check the status of a service.

# service status

92. Restart after shutdown and force fsck (fsck may take a while).

# shutdown -rF now

93. Split a file into pieces with numeric suffixes, so it can be burnt to cds.

# split -d -b 640k big_input_filename.gz piece_file_prefix.gz.

To piece it back you can `cat piece_file_prefix.gz.* > original.gz`
94. Determine if a network service binary is linked againt tcp wrapper, libwrap.a

# strings -f | grep hosts_access

96. how to use tar

# tar -cvzf fileName.tar.gz `find /file/path -mtime -1 ! -type d -print`

97.

# tar -xvzpf fileName.tar.gz /path/to/file.txt

98. How to use tcpdump

# tcpdump -i eth0 dst port 80 | more

99. System process status

# top

100. View the full command line.

# top -c

101. Create empty file of 0 byte

# touch

102. Similar to `which` - shows full path to the command.

# type

103. Check the limit of user

# ulimit -a

104. Check the version of kernel running

# uname -a

105. Update package profile with rhn

# up2date -p

106. Install package via up2date.

# up2date -i

107.

# uptime

108.

# usermod

109. Utility reports virtual memory statistics

# vmstat [second interval] [no. of count]

110. Show who is logged on and what they are doing.

# w

111. Periodically watch output of a command in full screen

# watch ''

112. Run and generate the apache reports using webalizer

# webalizer -c /path/to/webalizer.conf

113. Recursive download of a url, converting links, no parent.

# wget -r -k -np

114. Mirror, convert links, backup original, dynamic to html and output a “logFile”.

# wget -m -k -K -E -o [logFile]

115. Locate the binary, source, and manual page files for a command.

# whereis

116. Shows the full path of command.

# which

117. Show who is logged on.

# who

118. Yum package updates

# yum check-update           -- check to see what updates are needed
# yum info     -- show basic information about a package
# yum update   -- update particular package

119. Control jobs:

# Ctrl-z   -- suspend foreground job
# jobs     -- list jobs
# bg       -- send job to background
# fg       -- bring job to foreground

Check your Disk Performance

Using some simple command you can check the performance of hard disk

#hdparm -tT /dev/sda

Output:

/dev/sda:

Timing cached reads:   6054 MB in  2.00 seconds = 3028.86 MB/sec

Timing buffered disk reads:   42 MB in  3.09 seconds =  13.60 MB/sec

/dev/sda:

Timing cached reads:   6054 MB in  2.00 seconds = 3028.86 MB/sec

Timing buffered disk reads:   42 MB in  3.09 seconds =  13.60 MB/sec