RED HAT ENTERPRISE LINUX

iptables configuration file /etc/iptables.up.rules

# Generated by iptables-save v1.4.4 on Tue Jul 6 19:02:33 2010
*nat
:PREROUTING DROP [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A PREROUTING -d 8.8.8.8 -i eth1 -j ACCEPT
-A PREROUTING -d 4.4.4.4 -i eth1 -j ACCEPT
-A PREROUTING -d w.x.y.z -i eth1 -j ACCEPT #(old mail server ip)
-A PREROUTING -d a.b.c.d -i eth1 -j ACCEPT #(mail server ip)
-A PREROUTING -d mail.uvw.in -i eth1 -j ACCEPT
-A PREROUTING -d l.m.n.o/29 -i eth1 -j ACCEPT #(old network ip)
-A PREROUTING -d r.s.t.u -i eth1 -j ACCEPT #(proxy server ip)
-A PREROUTING -d 122.c.d.146 -i eth1 -j ACCEPT #(allow ip)
-A PREROUTING -d 122.e.f.147 -i eth1 -j ACCEPT #(allow ip)
# Samba and Proxy
-A PREROUTING -p tcp -m tcp -m multiport -i eth1 -j ACCEPT --dports 139,445,3128,9000
-A POSTROUTING -s 10.1.5.0/24 -o eth0 -j MASQUERADE
-A PREROUTING -p tcp -m tcp --dport 11500 -j ACCEPT
-A PREROUTING -p tcp -m tcp -m multiport -i eth1 -j REDIRECT --to-ports 3128 --dports 80,8080,9000
COMMIT
# Completed on Tue Jul 6 19:02:33 2010
# Generated by iptables-save v1.4.4 on Tue Jul 6 19:02:33 2010
*mangle
:PREROUTING ACCEPT [602:341342]
:INPUT ACCEPT [568:338000]
:FORWARD ACCEPT [34:3342]
:OUTPUT ACCEPT [676:370648]
:POSTROUTING ACCEPT [710:373990]
COMMIT
# Completed on Tue Jul 6 19:02:33 2010
# Generated by iptables-save v1.4.4 on Tue Jul 6 19:02:33 2010
*filter
:INPUT ACCEPT [568:338000]
:FORWARD ACCEPT [34:3342]
:OUTPUT ACCEPT [676:370648]
COMMIT
# Completed on Tue Jul 6 19:02:33 2010

Network/ethernet card configuration file Editing file /etc/network/interfaces

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
address w.x.y.z
netmask 255.255.255.248
gateway w.x.y.u
dns-nameservers a.b.c.d
metric 1
post-up iptables-restore < /etc/iptables.up.rules

#Secondary network interface
auto eth1
iface eth1 inet static
address 10.1.5.1
netmask 255.255.255.0
network 10.1.5.0
broadcast 10.1.5.255
metric 2

Relational Database - Codd's Rules

Relational Database - Codd's Rules !!!

A relational database management system (RDBMS) is a database management system (DBMS) that is based on the relational model as introduced by E. F. Codd. Most popular commercial and open source databases currently in use are based on the relational database model.

A short definition of an RDBMS may be a DBMS in which data is stored in the form of tables and the relationship among the data is also stored in the form of tables.

Codd's Rules

All database management must take place using the relational database's innate functionality
All information in the database must be stored as values in a table
All database information must be accessible through the combination of a table name, primary key and column name.
The database must use NULL values to indicate missing or unknown information
The database schema must be described using the relational database syntax
The database may support multiple languages, but it must support at least one language that provides full database functionality (e.g. SQL)
The system must be able to update all updatable views
The database must provide single-operation insert, update and delete functionality

Changes to the physical structure of the database must be transparent to applications and users.
Changes to the logical structure of the database must be transparent to applications and users.
The database must natively support integrity constraints.
Changes to the distribution of the database (centralized vs. distributed) must be transparent to applications and users.
Any languages supported by the database must not be able to subvert integrity controls.

Tags: database, table, DBMS, RDBMS, columns, Codd, E. F. Codd, rules, oracle, data

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Apt-Get command line tool

Apt-Get command line tool

(Ubuntu's Advanced Packaging Tool) !!!

The apt-get command is a powerful command-line tool used to work with Ubuntu's Advanced Packaging Tool (APT) performing such functions as installation of new software packages, upgrade of existing software packages, updating of the package list index, and even upgrading the entire Ubuntu system.

*Install package
#sudo apt-get install packagename

*Remove Package
#sudo apt-get remove packagename

*Install Multiple Packages
#sudo apt-get install packagename1 packagename2 packagename3

*Update the Package Index
#sudo apt-get update

The APT package index is essentially a database of available packages from the repositories defined in the /etc/apt/sources.list file.

*Upgrade the system
#sudo apt-get upgrade

*Read Debian APT User Manual
#sudo apt-get help

Tags: apt get apt-get advanced packaging tool install remove upgrade update help ubuntu linux unix package-management

Port Numbers - Linux

PORTS NUMBERS : Just as the physical address (MAC address) and the logical address (IP address) helps to route the traffic to a particular machine on a network, it is the port that identifies which service on the machine this traffic is destined to.

List of ports : /etc/services

A port on a specific computer is called a socket. It can be open, closed, listening or have a connection established.

###Important PORT NUMBERS to remember:

20 - FTP - data transfer

21 - FTP - control (command)

22 - SSH

23 - Telnet

25 - SMTP

37 - Time

43 - WHOIS

42 - WINS

53 - DNS

67 - BOOTp

68 - DHCP

69 - TFTP

79 - FINGER

80 - HTTP (WWW)

88 - Kerberose

101 - HOSTNAME

110 - POP3

111 - rpcbind

119 - NNTP

123 - NTP (Time)

137 - NetBios (nmbd)

139 - NetBios ( Samba)

143 - IMAP/Dovecot

161 - SNMP

180 - RIS

220 - IMAP3

389 - LDAP

443 - HTTPs

500 - Internet Key Exchange (IKE), IPSec

520 - RIP

546 - DHCPV6 client

547 - DHCPV6 server

554 - rtsp(Real Time Stream Protocol, Audio/Video)

631 - Printing (ipp)

744 - Flexlm

901 - SWAT

953 - rndc

993 - IMAPSecure

995 - POPs

999 - POP over SSL/TLS

2049 - NFS

2082 - CPANEL

2083 - CPANEL Secure SSL/TLS

2086 - CPANEL WHM

2087 - CPANEL WHM Secure/SSL

2095 - CPANEL Webmail

2096 - CPANEL Webmail Secure/SSL

2222 - Direct Admin Control Panel

2401 - CVSP server

3268 - AD Global Catalog

3269 - AD Global Catalog over SSL

3306 - MySQL Server

3389 - Terminal services (rdp-remote desktop protocol)

4643 - Virtusso Power Panel

(6000 - X11

6063)

8443 - Pleask Control Panel

9999 - Urchin

10000- Webmin Control Panel

21018- Skype

TAG: port, portnumber, port-numbers, tcp, udp, network, service, services, linux, socket, communication, transmission, dataflow, rhce, ubuntu, unix, red hat, red-hat, redhat

How to install Webmin

WEBMIN

Webmin is a web-based interface for system administration for Unix. Using any modern web browser, you can setup user accounts, Apache, DNS, file sharing and much more. Webmin removes the need to manually edit Unix configuration files like /etc/passwd, and lets you manage a system from the console or remotely.

Install Webmin (Successfully tested/configured on Ubuntu server 10.04)

#sudo aptitude safe-upgrade
#sudo aptitude update
#sudo mkdir downloads
#cd downloads
#sudo wget http://downloads.sourceforge.net/project/webadmin/webmin/1.510/webmin_1.510-2_all.deb?use_mirror=cdnetworks-us-1
or
#sudo wget http://downloads.sourceforge.net/project/webadmin/webmin/1.510/webmin_1.510-2_all.deb?use_mirror=kent
#sudo dpkg -i webmin_1.510-2_all.deb
#sudo aptitude -f install

=>>You can access the Ubuntu machine from a Windows machine via a web browser by typing the address

https://yourip:10000
or
https://core:10000 , here core is the name of my Ubuntu server.

Tags: webmin web-based interface system administration admistrator configure linux server ubuntu red hat redhat rhel rhce unix

How to break root password !!!

How to break root password !!!

Method 1:

One of the advantages of single-user mode is that you do not need a boot CD-ROM; however, it does not give you the option to mount the file systems as read-only or not mount them at all.

If your system boots, but does not allow you to log in when it has completed booting, try single-user mode.

In single-user mode, your computer boots to runlevel 1. Your local file systems are mounted, but your network is not activated. You have a usable system maintenance shell. Unlike rescue mode, single-user mode automatically tries to mount your file system. Do not use single-user mode if your file system cannot be mounted successfully. You cannot use single-user mode if the runlevel 1 configuration on your system is corrupted.

1) When you reach the grub screen press 'e' on linux.

2) Go to line which contains the word 'kernel' press 'e'

3) go to the end of that line and write 'linux single' or '1'

4) then press 'esc' twice and press 'b' to reboot the system

5) now wait for the prompt and then type 'passwd root'

6) enter new passwd

Method 2:

In emergency mode, you are booted into the most minimal environment possible. The root file system is mounted read-only and almost nothing is set up. The main advantage of emergency mode over single-user mode is that the init files are not loaded. If init is corrupted or not working, you can still mount file systems to recover data that could be lost during a re-installation.

1) Boot the computer with linux installation CD

2) Enter the linux rescue mode by entering the following command in boot screen

boot:linux rescue

3) When the sh prompt is reached, enter the following commands to change root password:

#chroot /mnt/sysimage

#passwd

The above step will prompt you to enter your new password

Tags: rhel rhel5 rhce rhct hack how to break root password

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