Ways To Attack a Network:

>>>>Ping

The IP address gives the attacker’s Internet address. The numerical address like 212.214.172.81 does not reveal much. You can use PING to convert the address into a domain name in WINDOWS: The Domain Name Service (DNS) protocol reveals the matching domain name. PING stands for “Packet Internet Groper” and is delivered with practically every Internet compatible system, including all current Windows versions.

Make sure you are logged on to the net. Open the DOS shell and enter
the following PING command:
Ping –a 123.123.12.1
Ping will search the domain name and reveal it. You will often have information on the provider the attacker uses e.g.:
dialup21982.gateway123.provider.com
Pinging is normally the first step involved in hacking the target. Ping uses

>>>>ICMP

(Internet Control Messaging Protocol) to determine whether the target host is reachable or not. Ping sends out ICMP Echo packets to the target host, if the target host is alive it would respond back with ICMP Echo reply packets.

All the versions of Windows also contain the ping tool. To ping a remote host follow the procedure below.
Click Start and then click Run. Now type ping <ip address or hostname>
(For example: ping yahoo.com)

This means that the attacker logged on using “provider.com”.
Unfortunately, there are several IP addresses that cannot be converted into domain names.
For more parameter that could be used with the ping command, go to
DOS prompt and type ping /?.

>>>>Ping Sweep

If you are undetermined about your target and just want a live system, ping sweep is the solution for you. Ping sweep also uses ICMP to scan for live systems in the specified range of IP addresses. Though Ping sweep is similar to ping but reduces the time involved in pinging a range of IP addresses. Nmap (http://www.insecure.org/) also contains an option
to perform ping sweeps.

>>>Tracert:

Tracert is another interesting tool available to find more interesting information about a remote host. Tracert also uses ICMP.

Tracert helps you to find out some information about the systems involved in sending data (packets) from source to destination. To perform a tracert follow the procedure below.

Tracer connects to the computer whose IP has been entered and reveals all stations starting from your Internet connection. Both the IP address as well as the domain name (if available) is displayed.

If PING cannot reveal a name, Traceroute will possibly deliver the name of the last or second last station to the attacker, which may enable conclusions concerning the name of the provider used by the attacker and the region from which the attacks are coming.

Go to DOS prompt and type tracert <destination address>
(For example: tracert yahoo.com).
But there are some tools available like Visual Traceroute which help you
even to find the geographical location of the routers involved.
http://www.visualware.com/visualroute

>>>Port Scanning:-

After you have determined that your target system is alive the next important step would be to perform a port scan on the target system. There are a wide range of port scanners available for free. But many of them uses outdated techniques for port scanning which could be easily recognized by the network administrator. Personally I like to use Nmap (http://www.insecure.org/) which has a wide range of options. You can download the NmapWin and its source code from:
http://www.sourceforge.net/projects/nmapwin.

Apart from port scanning Nmap is capable of identifying the Operating system being used, Version numbers of various services running, firewalls being used and a lot more.

Common ports:

Below is a list of some common ports and the respective services
running on the ports.

20 FTP data (File Transfer Protocol)

21 FTP (File Transfer Protocol)

22 SSH

23 Telnet

25 SMTP (Simple Mail Transfer Protocol)

53 DNS (Domain Name Service)

68 DHCP (Dynamic host Configuration Protocol)

79 Finger

80 HTTP

110 POP3 (Post Office Protocol, version 3)

137 NetBIOS-ns

138 NetBIOS-dgm

139 NetBIOS

143 IMAP (Internet Message Access Protocol)

161 SNMP (Simple Network Management Protocol)

194 IRC (Internet Relay Chat)

220 IMAP3 (Internet Message Access Protocol 3)

389 LDAP

443 SSL (Secure Socket Layer)

445 SMB (NetBIOS over TCP)

Besides the above ports they are even some ports known as Trojan ports used by Trojans that allow remote access to that system.

>>>>Vulnerability Scanning:

Every operating system or the services will have some vulnerabilities due to the programming errors. These vulnerabilities are crucial for a successful hack. Bugtraq is
an excellent mailing list discussing the vulnerabilities in the various system. The exploit code writers write exploit codes to exploit these vulnerabilities existing in a system.

There are a number of vulnerability scanners available to scan the host for known vulnerabilities. These vulnerability scanners are very important for a network administrator to audit the network security.

Some of such vulnerability scanners include Shadow Security Scanner,Stealth HTTP Scanner, Nessus, etc. Visit
http://www.securityfocus.com/ vulnerabilities and exploit codes of various operating systems. Packet storm security
(http://www.packetstormsecurity.com/) is also a nice pick.