Nmap
This page will include notes and things to remember for nmap along with some tips and tricks. Commands will be separated based on the usage and the protocols in different sub pages.
Nmap is a network scanner created by Gordon Lyon. Nmap is used to discover hosts and services on a computer network by sending packets and analysing the responses. This information can be used to determine vulnerabilities related to the services running on that port. Service and operating system enumeration can be carried out with the use of Nmap
An Evil bit in tcp protocol when set to 1 tells the network that the packet has some evil intent and secure systems should try to defend themselves against such packets
Classful ip addressing
Class A: ip address belonging to class A are assigned to the networks that contain a large number of hosts.
the higher order bit is always set to 0
Network ID is 8 bits long.
Host ID is 24 bits long.
Subnet mask is 255.x.x.x
126 network id and 16,777,214 host id.
Ranges from: 1.x.x.x to 126.x.x.x
Class B: IP address belonging to class B are assigned to the networks that ranges from medium-sized to large-sized networks.
the higher order bit is always set to 1 0
network id is 16 bits long. host id is 16 bits long
16384 network addresses.
65534 host addresses.
IP addresses belonging to class B ranges from 128.0.x.x – 191.255.x.x.
subnet mask: 255.255.x.x
Class C: IP address belonging to class C are assigned to small-sized networks.
The higher order bit is always set to 1 1 0
network ID is 24 bit long
host ID is 8 bits long
class D: reserved for multicasting. the higher order bits are always set to 1110
subnet mask: does not contain any.
class E: for experimental purposes. higher order bits are set to 1111
special addresses:
127.0.0.0-127.0.0.8: loop back addresses
0.0.0.0 – 0.0.0.8 : used to communicate within the current network
All bits of network ID set to 1 are reserved for use as an IP broadcast address and therefore, cannot be used.
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