Nmap, short for Network Mapper, is a free, open-source tool for vulnerability scanning and network discovery. Network administrators use Nmap to identify what devices are running on their systems, discovering hosts that are available and the services they offer, finding open ports and detecting security risks.
See https://en.wikipedia.org/wiki/Nmap
====
== Scan Ports
=== Scan a Single Port, All Ports, or Series
[source,bash]
----
Nmap commands can be used to scan a single port or a series of ports:
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=== Scan port 80 on the target system:
[source,bash]
----
nmap –p 80 172.21.0.3
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=== Scan ports 1 through 200 on the target system:
-rw-rw-r-- 1 zeus zeus 1517 Οκτ 23 21:55 INSTALL.md
-rw-rw-r-- 1 zeus zeus 33883 Οκτ 15 14:28 LICENSE
-rw-rw-r-- 1 zeus zeus 691 Οκτ 17 11:13 README.md
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=== To scan all ports (1 – 65535):
[source,bash]
----
nmap –p– 172.21.0.3
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==== File types
=== Scan All TCP UDP Ports
This table gives an overview of the characters determining the file type:
Scan all UDP and TCP ports in a single command. We will use -sU for UDP and sT for TCP protocol.
[source,bash]
----
nmap -sU -sT -p0-65535 IP
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.What Are Ports?
[NOTE]
====
On modern operating systems, ports are numbered addresses for network traffic. Different kinds of services use different ports by default.
For example, normal web traffic uses Port 80, while POP3 email uses Port 110. One of the ways that a firewall works is by allowing or restricting traffic over a particular port.
Because the ports into your computer can cause a security risk, it’s critical to know which ports are open and which are blocked.
====
> **d**rwxrwxr-x 4 zeus zeus 4096 Οκτ 14 20:24 install
== netstat
=== Listing (Almost all)
[source,bash]
----
netstat -antlupe
----
=== Listing TCP Ports connections
[source,bash]
----
netstat -at
----
.Netstat
[NOTE]
====
Netstat command displays various network related information such as network connections, routing tables, interface statistics, masquerade connections, multicast memberships etc.,
====
=== Listing UDP Ports connections
[source,bash]
----
netstat -au
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=== Listing all LISTENING Connections
[source,bash]
----
netstat -l
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=== Listing all TCP Listening Ports
[source,bash]
----
netstat -lt
----
=== Listing all UDP Listening Ports
[source,bash]
----
netstat -lu
----
=== Listing all UNIX Listening Ports
[source,bash]
----
netstat -lx
----
.File types in a long list
[options="header,footer"]
|=======================
|Symbol| Meaning
|-| Regular file
|d| Directory
|l| Link
|c| Special file
|s| Socket
|p| Named pipe
|b| Block device
|=======================
> -**rw-**rw-r-- 1 zeus zeus 1517 Οκτ 23 21:55 INSTALL.md
=== Showing Statistics by Protocol
==== Access rights
[source,bash]
----
netstat -s
----
=== Showing Statistics by TCP Protocol
.Access rights
[options="header,footer"]
|=======================
|Code| Meaning
|0 or -|The access right that is supposed to be on this place is not granted.
|4 or r|read access is granted to the user category defined in this place
|2 or w|write permission is granted to the user category defined in this place
|1 or x|execute permission is granted to the user category defined in this place
|=======================
[source,bash]
----
netstat -st
----
=== Showing Statistics by UDP Protocol
==== User group codes
[source,bash]
----
netstat -su
----
.User group codes
[options="header,footer"]
|=======================
|Code| Meaning|
|u| user permissions|-**rw-**rw-r--
|g| group permissions|-rw-**rw-***r--
|o| permissions for others|-rw-rw-**r--**
|=======================
=== Displaying Service name with PID
==== Exercises
[source,bash]
----
netstat -tp
touch example
chmod 400 example
ls -l example
chmod 500 example
ls -l example
chmod 600 example
ls -l example
chmod 644 example
ls -l example
chmod 660 example
ls -l example
chmod 700 example
ls -l example
chmod 755 example
ls -l example
chmod 775 example
ls -l example
ls -l example
chmod 777 example
ls -l example
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=== Displaying Promiscuous Mode
Displaying Promiscuous mode with -ac switch, netstat print the selected information or refresh screen every five second. Default screen refresh in every second. +
[source,bash]
----
netstat -ac 5 | grep tcp
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=== Setting Promiscuous Mode
[source,bash]
----
ifconfig eth0 promisc
OR
ip link set eth0 promisc on
----
=== Remove Promiscuous Mode
== Linux file system layout
[source,bash]
----
ifconfig eth0 –promisc
----
.Promiscuous Mode
[NOTE]
====
Promiscuous mode is a mode for a wired network interface controller (NIC) or wireless network interface controller (WNIC) that causes the controller to pass all traffic it receives to the central processing unit (CPU) rather than passing only the frames that the controller is specifically programmed to receive.
When a capable NIC is placed in Promiscuous Mode, it allows the NIC to intercept and read each arriving network packet in its entirety.
.Subdirectories of the root directory
[options="header,footer"]
|=======================
|Directory| Content
|/bin| Common programs, shared by the system, the system administrator and the users.
|/boot| The startup files and the kernel, vmlinuz. In some recent distributions also grub data. Grub is the GRand Unified Boot loader and is an attempt to get rid of the many different boot-loaders we know today.
|/dev| Contains references to all the CPU peripheral hardware, which are represented as files with special properties.
|/etc| Most important system configuration files are in /etc
|/home| Home directories of the common users.
|/lib| Library files, includes files for all kinds of programs needed by the system and the users.
|/mnt| Standard mount point for external file systems, e.g. a CD-ROM or a digital camera.
|/opt| Typically contains extra and third party software.
|/proc| A virtual file system containing information about system resources.
|/root| The administrative user's home directory. Mind the difference between /, the root directory and /root, the home directory of the root user.
|/sbin| Programs for use by the system and the system administrator.
|/tmp| Temporary space for use by the system, cleaned upon reboot, so don't use this for saving any work!
|/usr| Programs, libraries, documentation etc. for all user-related programs.
|/var| Storage for all variable files and temporary files created by users, such as log files, the mail queue, the print spooler area, space for temporary storage of files downloaded from the Internet, or to keep an image of a CD before burning it.
|=======================
If the NIC is not in Promiscuous Mode, it will only receive packets that are specifically addressed to the NIC. Promiscuous Mode must be supported by the NIC and by the operating system and any associated driver. Not all NICs support Promiscuous Mode, however it is pretty easy to determine if you have a NIC and OS capable of Promiscuous Mode.
====
=== check if promiscuous mode is enabled on network interface
Look under the last column “Flg” for value “P”. If it’s there, it means promiscuous mode is enabled for that network interface +
B flag is for broadcast +
M flag is for multicast +
P flag is for promisc mode +
R is for running +
U is for up +
====
[appendix]
== How to use Nmap
While the basis of Nmap's functionality is port scanning, it allows for a variety of related capabilities including:
- Network mapping: Nmap can identify the devices on a network (also called host discovery), including servers, routers and switches, and how they're physically connected.
- OS detection: Nmap can detect the operating systems running on network devices (also called OS fingerprinting), providing the vendor name, the underlying operating system, the version of the software and even an estimate of devices' uptime.
- Service discovery: Nmap can not only identify hosts on the network, but whether they're acting as mail, web or name servers, and the particular applications and versions of the related software they're running.
- Security auditing: Figuring out what versions of operating systems and applications are running on network hosts lets network managers determine their vulnerability to specific flaws. If a network admin receives an alert about a vulnerability in a particular version of an application, for example, she can scan her network to identify whether that software version is running on the network and take steps to patch or update the relevant hosts. Scripts can also automate tasks such as detecting specific vulnerabilities.
test2
5 years ago