Buenas,
pues mira, para empezar puedes usar un programa que se llama nmap, con el puedes hacerle un escaneo completo a la página y así podras ver que servicios ofrece la página.
Seguro seguro será el 80, pero puedes encontrar también el 21(ftp), 25/110(mail), puede que tenga BBDD, y si es así puede que te encuentres un phpMyAdmin...(nose, por imaginar...)

La idea es que veas que servicios tiene corriendo(y que versiones). Una vez recolectada toda esa información, debes buscar posibles vulnerabilidades para esos servicios(y esas versiones concretamente), y si tienes suerte y encuentras alguna, solo tienes que buscar el exploit, mirar como se usa y usarlo.

Todo eso si hay algún servicio vulnerable, si no lo hay... seria cuestión de echarle imaginación, pero primero agota recursos.

Ale, ya tienes faena!!

Ah! y si no sabes como usar nmap, mira en google!

Saludos!!

Sólo aclarar que los puertos corresponden a la seguridad del servidor web no de la página en sí.
 
Sí quieres encontrar fallos de programación lo mejor es revisar a mano aunque existen scanners pero no se recomiendan. Aprende el lenguaje en el que está programada la página y aplica creatividad

Mejor depende de lo que quieras.

Personalmente no sabia que nmap tenia interfaz gráfica.

Leete este post, ahí explican bastante bien lo básico y no tan básico del nmap. Para empezar ya está bien. Y si tienes alguna duda pregunta.

Saludos!!

wenas mira use Zenmap y la opcion intense scan plus UDP y saque este informe que opinais? lo ise bien ?



Starting Nmap 5.21 ( http://nmap.org ) at 2010-03-07 02:33 Hora estándar romance

NSE: Loaded 36 scripts for scanning.

Initiating Ping Scan at 02:33

Scanning 62.xxxxxxxx [8 ports]

Completed Ping Scan at 02:33, 0.27s elapsed (1 total hosts)

Initiating Parallel DNS resolution of 1 host. at 02:33

Completed Parallel DNS resolution of 1 host. at 02:33, 0.13s elapsed

Initiating SYN Stealth Scan at 02:33

Scanning webx133.aruba.it (6xxxxxxx) [1000 ports]

Discovered open port 80/tcp on 6xxxxxxxxxxxx

Discovered open port 21/tcp on 62xxxxxx

Completed SYN Stealth Scan at 02:34, 24.34s elapsed (1000 total ports)

Initiating UDP Scan at 02:34

Scanning webx133.aruba.it (6xxxxxxxx) [1000 ports]

Completed UDP Scan at 02:34, 7.13s elapsed (1000 total ports)

Initiating Service scan at 02:34

Scanning 1002 services on webx133.aruba.it (xxxxxxxx)

Service scan Timing: About 0.40% done

Service scan Timing: About 3.29% done; ETC: 03:52 (1:15:51 remaining)

Service scan Timing: About 6.29% done; ETC: 03:36 (0:57:53 remaining)

Service scan Timing: About 9.28% done; ETC: 03:30 (0:50:30 remaining)

Service scan Timing: About 12.28% done; ETC: 03:27 (0:46:13 remaining)

Service scan Timing: About 15.27% done; ETC: 03:25 (0:43:00 remaining)

Service scan Timing: About 21.16% done; ETC: 03:17 (0:34:06 remaining)

Service scan Timing: About 21.26% done; ETC: 03:23 (0:38:20 remaining)

Service scan Timing: About 27.15% done; ETC: 03:17 (0:31:29 remaining)

Service scan Timing: About 27.25% done; ETC: 03:21 (0:34:32 remaining)

Service scan Timing: About 33.13% done; ETC: 03:17 (0:28:54 remaining)

Service scan Timing: About 33.23% done; ETC: 03:21 (0:31:10 remaining)

Service scan Timing: About 39.12% done; ETC: 03:17 (0:26:18 remaining)

Service scan Timing: About 45.11% done; ETC: 03:17 (0:23:42 remaining)

Service scan Timing: About 51.10% done; ETC: 03:17 (0:21:07 remaining)

Service scan Timing: About 57.09% done; ETC: 03:17 (0:18:32 remaining)

Service scan Timing: About 63.07% done; ETC: 03:17 (0:15:57 remaining)

Service scan Timing: About 69.06% done; ETC: 03:17 (0:13:21 remaining)

Service scan Timing: About 75.05% done; ETC: 03:17 (0:10:46 remaining)

Service scan Timing: About 81.04% done; ETC: 03:17 (0:08:11 remaining)

Service scan Timing: About 87.03% done; ETC: 03:17 (0:05:36 remaining)

Service scan Timing: About 93.01% done; ETC: 03:17 (0:03:01 remaining)

Completed Service scan at 03:18, 2636.48s elapsed (1002 services on 1 host)

Initiating OS detection (try #1) against webx133.aruba.it (xxxxxxxxxxx)

Retrying OS detection (try #2) against webx133.aruba.it (62xxxxxxx)

Retrying OS detection (try #3) against webx133.aruba.it (62.xxxxxxxx)

Retrying OS detection (try #4) against webx133.aruba.it (62xxxxxxxxxxxxx)

Retrying OS detection (try #5) against webx133.aruba.it (62.xxxxxxxx)

Initiating Traceroute at 03:18

Completed Traceroute at 03:18, 3.06s elapsed

Initiating Parallel DNS resolution of 13 hosts. at 03:18

Completed Parallel DNS resolution of 13 hosts. at 03:18, 0.41s elapsed

NSE: Script scanning 62.xxxxxxxxx.

NSE: Starting runlevel 1 (of 1) scan.

Initiating NSE at 03:18

Completed NSE at 03:19, 30.19s elapsed

NSE: Script Scanning completed.

Nmap scan report for webx133.aruba.it (6xxxxxxxxxx)

Host is up (0.15s latency).

Not shown: 1000 open|filtered ports, 987 filtered ports

PORT      STATE  SERVICE  VERSION

20/tcp    closed ftp-data

21/tcp    open   ftp      PureFTPd

80/tcp    open   http     Apache httpd 2.2

|_html-title:             webx133.aruba.it        

50000/tcp closed iiimsf

50001/tcp closed unknown

50002/tcp closed iiimsf

50003/tcp closed unknown

50006/tcp closed unknown

50300/tcp closed unknown

50389/tcp closed unknown

50500/tcp closed unknown

50636/tcp closed unknown

50800/tcp closed unknown

No exact OS matches for host (If you know what OS is running on it, see http://nmap.org/submit/ ).

TCP/IP fingerprint:

OS:SCAN(V=5.21%D=3/7%OT=21%CT=20%CU=%PV=N%DS=15%DC=T%G=Y%TM=4B930D27%P=i686

OS:-pc-windows-windows)SEQ(SP=C4%GCD=1%ISR=CA%TI=Z%CI=Z%II=I%TS=A)SEQ(SP=C5

OS:%GCD=1%ISR=CB%TI=Z%CI=Z%II=I%TS=D)SEQ(CI=Z%II=I)OPS(O1=M5B4ST11NW7%O2=M5

OS:B4ST11NW7%O3=M5B4NNT11NW7%O4=M5B4ST11NW7%O5=M5B4ST11NW7%O6=M5B4ST11)OPS(

OS:O1=NNT11%O2=NNT11%O3=NNT11%O4=M5B4ST11NW7%O5=NNT11%O6=NNT11)OPS(O1=NNT11

OS:%O2=NNT11%O3=NNT11%O4=NNT11%O5=NNT11%O6=NNT11)WIN(W1=16A0%W2=16A0%W3=16A

OS:0%W4=16A0%W5=16A0%W6=16A0)ECN(R=Y%DF=Y%TG=40%W=16D0%O=M5B4NNSNW7%CC=N%Q=

OS:)ECN(R=Y%DF=Y%TG=40%W=16D0%O=%CC=N%Q=)T1(R=Y%DF=Y%TG=40%S=O%A=S+%F=AS%RD

OS:=0%Q=)T1(R=Y%DF=Y%TG=40%S=O%A=O%F=A%RD=0%Q=)T1(R=Y%DF=Y%TG=40%S=O%A=O%F=

OS:AS%RD=0%Q=)T2(R=Y%DF=Y%TG=40%W=0%S=Z%A=S%F=AR%O=%RD=0%Q=)T3(R=N)T4(R=Y%D

OS:F=Y%TG=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T5(R=Y%DF=Y%TG=40%W=0%S=Z%A=S+%F=AR

OS:%O=%RD=0%Q=)T6(R=Y%DF=Y%TG=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T7(R=Y%DF=Y%TG=

OS:40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1(R=N)IE(R=Y%DFI=N%TG=40%CD=S)



Network Distance: 15 hops



TRACEROUTE (using port 50001/tcp)

HOP RTT       ADDRESS

1   203.00 ms 212-166-251-122.red-acceso.airtel.net (2xxxxxxxxxxx)

2   ...

3   203.00 ms 85.205.24.221

4   203.00 ms 213.242.109.153

5   219.00 ms ae-0-11.bar1.Madrid2.Level3.net (4.69.141.45)

6   219.00 ms ae-5-5.ebr1.Paris1.Level3.net (4.69.141.42)

7   157.00 ms ae-1-51.edge1.Paris1.Level3.net (4.69.139.199)

8   ...

9   219.00 ms RMAS-T02-RMID-I02-po02.wind.it (21xxxxxxxxx
10  219.00 ms 151.6.7.45

11  140.00 ms 151.6.6.178

12  110.00 ms 151.6.65.234

13  250.00 ms 151.5.151.98

14  125.00 ms MSFC3PX.aruba.it (62xxxxxxxxxx)

15  125.00 ms webx133.aruba.it (62xxxxxxxx)



Read data files from: C:\Nmap

OS and Service detection performed. Please report any incorrect results at http://nmap.org/submit/ .

Nmap done: 1 IP address (1 host up) scanned in 2733.16 seconds

           Raw packets sent: 5128 (202.888KB) | Rcvd: 149 (8212B)

no llego a entender pero me dice que hay 2 puertos abiertos al principio y luego ninguno no ?? esque soy mu nuevo en esto aun