Nmap: TCP ACK Ping and UDP Ping (part-15)

TCP ACK Ping




The -PA performs a TCP ACK ping on the specified target.
Usage syntax: nmap -PA[port1,port1,etc] [target]

# nmap -PA 192.168.1.254
Starting Nmap 5.00 ( http://nmap.org ) at 2009-08-16 13:31 CDT
Interesting ports on home (192.168.1.254):
Not shown: 998 closed ports
PORT STATE SERVICE
80/tcp open
443/tcp open
http
https
MAC Address: 00:25:3C:5F:5A:89 (2Wire)
Nmap done: 1 IP address (1 host up) scanned in 0.81 seconds

Performing a TCP ACK ping


The -PA option causes Nmap to send TCP ACK packets to the specified hosts. This method attempts to discover hosts by responding to TCP connections that are nonexistent in an attempt to solicit a response from the target. Like other ping options, it is useful in situations where standard ICMP pings are blocked.
 
note
The default port for -PA is 80, but others can be specified using the 50 following syntax: nmap -PA22,25,80,443,etc.


UDP Ping

The -PU option performs a UDP ping on the target system.


Usage syntax: nmap -PU[port1,port1,etc] [target]

# nmap -PU 192.168.1.254
Starting Nmap 5.00 ( http://nmap.org ) at 2009-08-16 13:30 CDT
Interesting ports on home (192.168.1.254):
Not shown: 998 closed ports
PORT STATE SERVICE
80/tcp open
443/tcp open
http
https
MAC Address: 00:25:3C:5F:5A:89 (2Wire)
Nmap done: 1 IP address (1 host up) scanned in 0.81 second

Performing a UDP ping


This discovery method sends UPD packets in an attempt to solicit a response from a
target. While most firewalled systems will block this type of connection, some
poorly configured systems may allow it if they are only configured to filter TCP
connections.







note
The default port for -PU is 40125. Others can be specified by using the
following syntax: nmap -PU22,25,80,443,etc.