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Nmap scanning

Basics Concepts

MAC

  • 48 bits
  • 6 bytes long
  • Hex representation

DE:AD:BE:EF:CA:FE

  • First 6 is OUI (Org unique identifier)
  • Last 6 is extension indentifier

IPV4

  • 32 bit address
  • 4 octets
  • Can be represented as Decimal 3232323232
  • Can be represented as HEX C0A8010
  • 2^32 Addressse possible (4.3 billion)

Fregmentation

Some network has MTU (maximum transmission unit) which is the maximu packet size that can be send over netowrk so sometime packets need to be broke down in smaller units called the process of fragmentation.

Classful Netoworks

The Huge 1.4 billion ip addresses are converted in small classes

Class Range Leading Bits
A 1.6 million 0
B 65535 10
C 256 110
D Undefined 1110
E Undefined 1111

ARP:

  • Adress Resolution protocol
  • Used to find the Layer 2 Mac addresses for Layer 3 Ip addresses

ICMP:

  • Internet control message Protocol
  • Use to help other protocols
  • Used for troubleshooting and error reporting
  • Uses Types and codes instead of ports

PING: TCP: PORTS: Traceroute:

Connect Scan (-sT)

Open port:

  • A --> Syn --> B
  • A <-- Syn Ack <-- B
  • A --> ACK --> B
  • A --> RST/ACK --> B (To Reset/Close the connection)

Close Port:

  • A --> Syn --> B
  • A <-- RST/Ack <-- B

Syn Scan (-sS)

Open port:

  • A --> Syn --> B
  • A <-- SYN/ACK <-- B
  • A --> RST --> B (To Reset/Close the connection)

Close Port:

  • A --> Syn --> B
  • A <-- RST/Ack <-- B

Port Status

Status Meaning
Closed ICMP Port Unrecheable error
Filtered ICMP Port Unrecheable error
Open/Filtered No response
Open Any Response

Scanning

Simple scan

root@root:~# nmap localhost

Simple TCP scan (Explicit 3 way handshake scan)

root@root:~# nmap -sT localhost

Simple UDP Scan

root@root:~# nmap -sU localhost

Nmap OS scan

root@root:~# nmap -p80 -O localhost

Nmap Service Detection

root@root:~# nmap -sV -p80 localhost

Dont ping just Scan

root@root:~# nmap -PN -p80 localhost

Nmap Aggressive Scan

root@root:~# nmap -A localhost

Nmap ACK Scan

root@root:~# nmap -sA localhost

Nmap FIN Scan (Use fin Packets)

root@root:~# nmap -sF localhost

Nmap ACK Scan

root@root:~# nmap -sA localhost

Nmap Xmas Scan

root@root:~# nmap -sX localhost

Nmap Fast Mode (Top 100 Ports)

root@root:~# nmap -F localhost

Different Ping Scans

No port scanning (to check if the host is up)

root@root:~# nmap 127.0.0.1-5 -sn

ARP ping scan

nmap -PR 127.0.0.1

No ping Scan

nmap -Pn 127.0.0.1

ICMP ping Scan

nmap -PI 127.0.0.1

ICMP Echo ping Scan

nmap -PE 127.0.0.1

No Timestamp Scan

nmap -PP 127.0.0.1

SYN ping Scan (Much like SYN scan but with ACK)

nmap -PP 127.0.0.1

UDP ping Scan

nmap -PU 127.0.0.1

TCP ping Scan

nmap -P 127.0.0.1

Nmap Protocol Scan

nmap -sO 127.0.0.1

Nmap DNS lookup Scan

nmap -sL 127.0.0.1

Nmap Never DNS lookup Scan

nmap -n 127.0.0.1

Nmap Traceroute Scan

nmap --traceroute google.com

Wildcards

The targets can be specified in 3 different ways

  • Wildcards -- 192.168.43.*
  • Range -- 192.168.0-255.0-255
  • CIDR -- 192.168.0.0/16

Options:

nmap 192.168.43.*
nmap 192.168.43.0-255
nmap 192.168.43.0/10

Other Options:

Nmap debug mode

nmap -p80 localhost -d

Nmap More debug mode

nmap -p80 localhost -ddd

Randomize Hosts while scanning

root@root:~# nmap 192.168.43.200-239 --randomize_hosts -f

Specify Network Interface

root@root:~# nmap 192.168.43.200-239 --randomize_hosts -f

Nmap Use packets fragmentation

root@root:~# nmap 192.168.43.239 -f

Nmap Verbose

root@root:~# nmap 192.168.43.239 -v

Nmap Very Verbose

root@root:~# nmap 192.168.43.239 -vv

Nmap show Reason

root@root:~# nmap 192.168.43.239 -p80,21 --open --reason

To exclude the Host

nmap 127.0.0.1-255 --exclude 127.0.0.1

Input list

nmap 127.0.0.1-255 -iL hosts.txt

Exclude the range of ip addresses

nmap 127.0.0.1-255 --excludefile hosts.list

Script Engine

Simple Script scan

nmap 192.168.43.* --script script-name

Default Script scan

nmap 192.168.43.* -sC script-name

Catogary Script scan

nmap 192.168.43.* --script safe|intrusive|malware|version|discovery|vuln|auth|default

Ports

Top 1000 Ports

nmap 192.168.43.*

All ports

nmap -p- localhost

Port range

nmap -p 0-65535 localhost

All from 1-3

nmap 192.168.43.* -p1-3


__All from 1-3__
```console
nmap 192.168.43.* -p-3

All from 1 to all

nmap 192.168.43.* -p1-

Specific Ports

nmap 192.168.43.1/24 -p 80

Top Ports

nmap 192.168.43.1/24 --top-ports 500 80

TCP and UDP Ports

nmap 192.168.43.1/24 -p T:80,U:53

Show only open ports

root@root:~# nmap 192.168.43.239 -p- --open

Mixed Style

root@root:~# nmap 192.168.43.239 -p80,21-25,8080-8090 --open

Logging

Show All packets Send and Receaved

nmap localhost --packet-trace

Nmap Simple Human Normal Output

root@root:~# nmap 192.168.43.239 -p- -oN output.file

Nmap Simple XML Redeable Output

root@root:~# nmap 192.168.43.239 -p- -oX output.file

Nmap Simple Grepabel Output

root@root:~# nmap 192.168.43.239 -p- -oG output.file

Nmap Simple All Output

root@root:~# nmap 192.168.43.239 -p- -oA output.file

Os and Version detectio

_Nmap OS detection needs atleast one Open port and One closed Port on the machine.

default os scan

nmap -O 192.168.43.239

Nmap Service Detection

root@root:~# nmap -sV -p80 localhost

Limit Os scan(Dont waste too much time if you are not able to detect OS)

nmap -O --osscan-limit 192.168.43.239

Aggresive Os scan(Spend too much time if you are not able to detect OS)

nmap -O --osscan-guess 192.168.43.239

Version Intensity (level=1,2,3,4,5,7,8,9)

nmap 192.168.43.239 --version-intensity <level>

High Version Intensity (level=9)

nmap 192.168.43.239 --version-all

Performance

Min Parallelism(minimum hosts to be scanned parallely)

nmap 192.168.43.0-255 --min-parallelism 10

Max Parallelism(Maximum hosts to be scanned parallely)

nmap 192.168.43.0-255 --max-parallelism 10

Host Timeout(give up on this target after this time default:30min)

nmap 192.168.43.0-255 --host-time <time>

Min Packet Rate(rate can be 1-100000000000)

nmap 192.168.43.0-255 --min-rate <Number>

Max Packet Rate(rate can be 1-100000000000)

nmap 192.168.43.0-255 --max-rate <Number>

Scan delay(Adjust delay between probes)

nmap 192.168.43.0-255 --scan-delay <time>

Performance template(-T(1|2|3|4|5)

nmap 192.168.43.0-255 -T1

T1

  hostgroups: min 1, max 100000
  rtt-timeouts: init 15000, min 100, max 15000
  max-scan-delay: TCP 1000, UDP 1000, SCTP 1000
  parallelism: min 0, max 1
  max-retries: 10, host-timeout: 0
  min-rate: 0, max-rate: 0

T2

  hostgroups: min 1, max 100000
  rtt-timeouts: init 1000, min 100, max 10000
  max-scan-delay: TCP 1000, UDP 1000, SCTP 1000
  parallelism: min 0, max 1
  max-retries: 10, host-timeout: 0
  min-rate: 0, max-rate: 0

T3

  hostgroups: min 1, max 100000
  rtt-timeouts: init 1000, min 100, max 10000
  max-scan-delay: TCP 1000, UDP 1000, SCTP 1000
  parallelism: min 0, max 0
  max-retries: 10, host-timeout: 0
  min-rate: 0, max-rate: 0

T4

  hostgroups: min 1, max 100000
  rtt-timeouts: init 500, min 100, max 1250
  max-scan-delay: TCP 10, UDP 1000, SCTP 10
  parallelism: min 0, max 0
  max-retries: 6, host-timeout: 0
  min-rate: 0, max-rate: 0

T5

  hostgroups: min 1, max 100000
  rtt-timeouts: init 250, min 50, max 300
  max-scan-delay: TCP 5, UDP 1000, SCTP 5
  parallelism: min 0, max 0
  max-retries: 2, host-timeout: 900000
  min-rate: 0, max-rate: 0

How it works

How OS detection Works

There is an file /usr/share/nmap/nmap-os-db which contain the patterns like this

CPE cpe:/h:2wire:1701hg
SEQ(SP=7E-9A%GCD=1-6%ISR=9E-A8%TI=I%TS=A)
OPS(O1=M5ACNNSW0NNNT11%O2=M578NNSW0NNNT11%O3=M280W0NNNT11%O4=M218NNSW0NNNT11%O5=M218NNSW0NNNT11%O6=M109NNSNNT11)
WIN(W1=8000%W2=8000%W3=8000%W4=8000%W5=8000%W6=8000)
ECN(R=Y%DF=Y%T=FA-104%TG=FF%W=8000%O=M5ACNNSW0N%CC=N%Q=)
T1(R=Y%DF=Y%T=FA-104%TG=FF%S=O%A=O|S+%F=AS%RD=0%Q=)
T2(R=N)
T3(R=N)
T4(R=Y%DF=Y%T=FA-104%TG=FF%W=0%S=A%A=Z%F=R%O=%RD=E44A4E43%Q=)
T5(R=Y%DF=Y%T=FA-104%TG=FF%W=0%S=Z%A=S+%F=AR%O=%RD=BD1AB510%Q=)
T6(R=Y%DF=Y%T=FA-104%TG=FF%W=0%S=A%A=Z%F=R%O=%RD=EA6C967D%Q=)
T7(R=N)
U1(DF=Y%T=FA-104%TG=FF%IPL=70%UN=0%RIPL=G%RID=G%RIPCK=G%RUCK=G%RUD=G)

How nmap Detect Services

There is an file /usr/share/nmap/nmap-services which contain the list of port number and an expected services on those port

vettcp	78/tcp	0.000000
vettcp	78/udp	0.000626
finger	79/tcp	0.006022
finger	79/udp	0.000956
http	80/sctp	0.000000	# www-http | www | World Wide Web HTTP
http	80/tcp	0.484143	# World Wide Web HTTP
http	80/udp	0.035767	# World Wide Web HTTP
hosts2-ns	81/tcp	0.012056	# HOSTS2 Name Server
hosts2-ns	81/udp	0.001005	# HOSTS2 Name Server
xfer	82/tcp	0.002923	# XFER Utility
xfer	82/udp	0.000659	# XFER Utility
mit-ml-dev	83/tcp	0.000539	# MIT ML Device
mit-ml-dev	83/udp	0.001203	# MIT ML Device
ctf	84/tcp	0.000276	# Common Trace Facility
ctf	84/udp	0.000610	# Common Trace Facility
mit-ml-dev	85/tcp	0.000690	# MIT ML Device
mit-ml-dev	85/udp	0.000610	# MIT ML Device
mfcobol	86/tcp	0.000138	# Micro Focus Cobol

So even starting an HTTP server on port 3306 will result showing up Mysql detected by Nmap.

root@root:~# python -m SimpleHTTPServer 3306
Serving HTTP on 0.0.0.0 port 3306 ...

root@root:~# nmap localhost
Starting Nmap 7.70 ( https://nmap.org ) at 2020-03-24 19:22 HDT
Nmap scan report for localhost (127.0.0.1)
Host is up (0.0000060s latency).
Other addresses for localhost (not scanned): ::1
Not shown: 998 closed ports
PORT     STATE SERVICE
80/tcp   open  http
3306/tcp open  mysql

But using -sV scan flag will actually force nmap to communicate to the server and detect the service

There is an aother file called /usr/share/nmap/nmap-service-probes which containes the regular expression to detect services based on the response

Let search SimpleHTTPServer in the file

root@root:/usr/share/nmap# cat nmap-service-probes  | grep SimpleHTTPServer
match http m|^HTTP/1\.0 501 Not Implemented\r\nServer: SimpleHTTP/([\w._-]+) Python/([\w._-]+)\r\n.*Content-Type: text/html\r\nConnection: close\r\n\r\n<head>\n<title>Error response</title>\n</head>\n<body>\n<h1>Error response</h1>\n<p>Error code 501\.\n<p>Message: Not Implemented\.\n<p>Error code explanation: 501 = Server does not support this operation\.\n</body>\n$|s p/SimpleHTTPServer/ v/$1/ i/rPath Appliance Platform Agent; Python $2/ cpe:/a:python:python:$2/ cpe:/a:python:simplehttpserver:$1/
match http m|^HTTP/1\.0 200 OK\r\nServer: SimpleHTTP/([\d.]+) Python/([\d.]+)\r\n| p/SimpleHTTPServer/ v/$1/ i/Python $2/ cpe:/a:python:python:$2/ cpe:/a:python:simplehttpserver:$1/

You can see that if ^HTTP/1\.0 200 OK\r\nServer: SimpleHTTP/([\d.]+) is matched with any of the response it will be marked as http.

So i tried to communicate with the SimpleHTTPServer with Curl to see the response Here is what i saw

root@root:/usr/share/nmap# curl -I localhost:3306
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.15+
Date: Wed, 25 Mar 2020 04:42:01 GMT
Content-type: text/html; charset=UTF-8
Content-Length: 3614

You can see the SimpleHTTP/0.6 matching SimpleHTTP/([\d.]+) Regex which confimed nmap that its an http service.

root@root:~# nmap -sV localhost
Starting Nmap 7.70 ( https://nmap.org ) at 2020-03-24 19:27 HDT
Nmap scan report for localhost (127.0.0.1)
Host is up (0.0000030s latency).
Other addresses for localhost (not scanned): ::1
Not shown: 998 closed ports
PORT     STATE SERVICE VERSION
80/tcp   open  http    Apache httpd 2.4.34
3306/tcp open  caldav  Radicale calendar and contacts server (Python BaseHTTPServer)
Service Info: Host: 127.0.0.1

You can have a look at on the server that direct connection was made by nmap for detecting services

127.0.0.1 - - [24/Mar/2020 19:27:57] code 400, message Bad request syntax ('\x00\x1e\x00\x06\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x07version\x04bind\x00\x00\x10\x00\x03')
127.0.0.1 - - [24/Mar/2020 19:27:57] "����version�bind��" 400 -
127.0.0.1 - - [24/Mar/2020 19:28:02] code 400, message Bad HTTP/0.9 request type ('\x00')
127.0.0.1 - - [24/Mar/2020 19:28:02] "
                                      �" 400 -
127.0.0.1 - - [24/Mar/2020 19:28:02] code 400, message Bad request syntax ('HELP')
127.0.0.1 - - [24/Mar/2020 19:28:02] "HELP" 400 -
127.0.0.1 - - [24/Mar/2020 19:28:02] "GET / HTTP/1.0" 200 -
127.0.0.1 - - [24/Mar/2020 19:28:02] code 404, message File not found
127.0.0.1 - - [24/Mar/2020 19:28:02] "GET /nmaplowercheck1585110482 HTTP/1.1" 404 -
127.0.0.1 - - [24/Mar/2020 19:28:02] code 501, message Unsupported method ('POST')
127.0.0.1 - - [24/Mar/2020 19:28:02] "POST /sdk HTTP/1.1" 501 -
127.0.0.1 - - [24/Mar/2020 19:28:02] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [24/Mar/2020 19:28:02] code 404, message File not found
127.0.0.1 - - [24/Mar/2020 19:28:02] "GET /HNAP1 HTTP/1.1" 404 -
127.0.0.1 - - [24/Mar/2020 19:28:02] code 404, message File not found
127.0.0.1 - - [24/Mar/2020 19:28:02] "GET /evox/about HTTP/1.1" 404 -

Tip

Use diff Linux command to see if there is any new service or host detected in the network

Pending http://www.irongeek.com/i.php?page=videos/nmap-class-hfc-louisville-issa&mode=print