Target Enumeration and Port Scanning Techniques
◾
115
Fragmented Packets
During fragmentation we split the packets into small chunks making it harder for the IDS to
detect. They can get past some IDS because the IDS would analyze a
single fragment but not all
the packets. Therefore they will not find anything suspicious. However, many modern IDS can
rebuild the
fragments into a single packet, making them detectable.
Example
nmap –f 192.168.15.1
Wireshark Output
This output shows us that the packets are divided into 8 bytes of data.
Source Port Scan
It is very common for a network administrator to allow traffic from a certain source port. We can
use this to our advantage to bypass badly configured firewalls. Common
ports that we can specify
as source are 53, 80, and 21.