Networking

IPv4 Subnet CIDR List

Netmask                Netmask (binary)                                 CIDR     Notes   
_____________________________________________________________________________
255.255.255.255  11111111.11111111.11111111.11111111   /32        Host (single addr)
255.255.255.254  11111111.11111111.11111111.11111110   /31        Unuseable
255.255.255.252  11111111.11111111.11111111.11111100   /30        2  useable
255.255.255.248  11111111.11111111.11111111.11111000   /29        6  useable
255.255.255.240  11111111.11111111.11111111.11110000   /28       14  useable
255.255.255.224  11111111.11111111.11111111.11100000   /27       30  useable
255.255.255.192  11111111.11111111.11111111.11000000   /26       62  useable
255.255.255.128  11111111.11111111.11111111.10000000   /25      126  useable
255.255.255.0      11111111.11111111.11111111.00000000   /24      "Class C" 254 useable

255.255.254.0      11111111.11111111.11111110.00000000   /23      2  Class C's
255.255.252.0      11111111.11111111.11111100.00000000   /22      4  Class C's
255.255.248.0      11111111.11111111.11111000.00000000   /21      8  Class C's
255.255.240.0      11111111.11111111.11110000.00000000   /20     16  Class C's
255.255.224.0      11111111.11111111.11100000.00000000   /19     32  Class C's
255.255.192.0      11111111.11111111.11000000.00000000   /18     64  Class C's
255.255.128.0      11111111.11111111.10000000.00000000   /17    128  Class C's
255.255.0.0          11111111.11111111.00000000.00000000   /16     "Class B"
    
255.254.0.0          11111111.11111110.00000000.00000000   /15     2  Class B's
255.252.0.0          11111111.11111100.00000000.00000000   /14     4  Class B's
255.248.0.0          11111111.11111000.00000000.00000000   /13     8  Class B's
255.240.0.0          11111111.11110000.00000000.00000000   /12    16  Class B's
255.224.0.0          11111111.11100000.00000000.00000000   /11    32  Class B's
255.192.0.0          11111111.11000000.00000000.00000000   /10    64  Class B's
255.128.0.0          11111111.10000000.00000000.00000000   /9     128  Class B's
255.0.0.0              11111111.00000000.00000000.00000000   /8      "Class A"
 
254.0.0.0              11111110.00000000.00000000.00000000   /7
252.0.0.0              11111100.00000000.00000000.00000000   /6
248.0.0.0              11111000.00000000.00000000.00000000   /5
240.0.0.0              11110000.00000000.00000000.00000000   /4
224.0.0.0              11100000.00000000.00000000.00000000   /3
192.0.0.0              11000000.00000000.00000000.00000000   /2
128.0.0.0              10000000.00000000.00000000.00000000   /1
0.0.0.0                  00000000.00000000.00000000.00000000   /0     IP space

Common FTP Commands

?	to request help or information about the FTP commands
ascii	to set the mode of file transfer to ASCII (this is the default and transmits seven bits per character)
binary	to set the mode of file transfer to binary (the binary mode transmits all eight bits per byte and thus provides less chance of a transmission error and must be used to transmit files other than ASCII files)
bye	to exit the FTP environment (same as quit)
cd	to change directory on the remote machine
close	to terminate a connection with another computer
	close brubeck	closes the current FTP connection with brubeck,   but still leaves you within the FTP environment.
delete	to delete (remove) a file in the current remote directory (same as rm in UNIX)
get	to copy one file from the remote machine to the local machine
	get ABC DEF	copies file ABC in the current remote directory to (or on top of) a file named DEF in your current local directory.
	get ABC	copies file ABC in the current remote directory to (or on top of) a file with the same name, ABC, in your current local directory.
help	to request a list of all available FTP commands
lcd	to change directory on your local machine (same as UNIX cd)
ls	to list the names of the files in the current remote directory
mkdir	to make a new directory within the current remote directory
mget	to copy multiple files from the remote machine to the local machine;   you are prompted for a y/n answer before transferring each file
	mget *	copies all the files in the current remote directory to your current local directory, using the same filenames. Notice the use of the wild card character, *.
mput	to copy multiple files from the local machine to the remote machine;   you are prompted for a y/n answer before transferring each file
open	to open a connection with another computer
	open brubeck	opens a new FTP connection with brubeck;   you must enter a username and password for a brubeck account       (unless it is to be an anonymous connection).
put	to copy one file from the local machine to the remote machine
pwd	to find out the pathname of the current directory on the remote machine
quit	to exit the FTP environment (same as bye)
rmdir	to to remove (delete) a directory in the current remote directory

List of FTP commands for the Microsoft command-line FTP client

Command-line options

As you're starting the program from a DOS prompt:
ftp [-v] [-d] [-i] [-n] [-g] [-s:filename] [-a] [-w:windowsize] [computer]

• -v - Suppresses verbose display of remote server responses.
• -n - Suppresses auto-login upon initial connection.
• -i - Turns off interactive prompting during multiple file transfers.
• -d - Enables debugging, displaying all ftp commands passed between the client and server.
• -g - Disables filename globbing, which permits the use of wildcard chracters in local file and path names.
• -s:filename - Specifies a text file containing ftp commands; the commands will automatically run after ftp starts. No spaces are allowed in this parameter. Use this switch instead of redirection (>).
• -a - Use any local interface when binding data connection.
• -w:windowsize - Overrides the default transfer buffer size of 4096.
• computer - Specifies the computer name or IP address of the remote computer to connect to. The computer, if specified, must be the last parameter on the line.

 

Client commands

• ! - Runs the specified command on the local computer
• ? - Displays descriptions for ftp commands
• append - Appends a local file to a file on the remote computer
• ascii - Sets the file transfer type to ASCII, the default
• bell - Toggles a bell to ring after each file transfer command is completed (default = OFF)
• binary - Sets the file transfer type to binary
• bye - Ends the FTP session and exits ftp
• cd - Changes the working directory on the remote computer
• close - Ends the FTP session and returns to the command interpreter
• debug - Toggles debugging (default = OFF)
• delete - Deletes a single file on a remote computer
• dir - Displays a list of a remote directory's files and subdirectories
• disconnect - Disconnects from the remote computer, retaining the ftp prompt
• get - Copies a single remote file to the local computer
• glob - Toggles filename globbing (wildcard characters) (default = ON)
• hash - Toggles hash-sign (#) printing for each data block transferred (default = OFF)
• help - Displays descriptions for ftp commands
• lcd - Changes the working directory on the local computer
• literal - Sends arguments, verbatim, to the remote FTP server
• ls - Displays an abbreviated list of a remote directory's files and subdirectories
• mdelete - Deletes one or more files on a remote computer
• mdir - Displays a list of a remote directory's files and subdirectories
• mget - Copies one or more remote files to the local computer
• mkdir - Creates a remote directory
• mls - Displays an abbreviated list of a remote directory's files and subdirectories
• mput - Copies one or more local files to the remote computer
• open - Connects to the specified FTP server
• prompt - Toggles prompting (default = ON)
• put - Copies a single local file to the remote computer
• pwd - Displays the current directory on the remote computer (literally, "print working directory")
• quit - Ends the FTP session with the remote computer and exits ftp (same as "bye")
• quote - Sends arguments, verbatim, to the remote FTP server (same as "literal")
• recv - Copies a remote file to the local computer
• remotehelp - Displays help for remote commands
• rename - Renames remote files
• rmdir - Deletes a remote directory
• send - Copies a local file to the remote computer (same as "put")
• status - Displays the current status of FTP connections
• trace - Toggles packet tracing (default = OFF)
• type - Sets or displays the file transfer type (default = ASCII)
• user - Specifes a user to the remote computer
• verbose - Toggles verbose mode (default = ON)

NMAP Commands

Basic Scan: nmap [target ip]

Scan A Range Of IPs: nmap [target ip - target ip] eg. nmap 192.168.0-4.1-255

Scan Specific Ports: nmap -p[port no.],[port no.] [target ip]

Scan And Get Service Versions: nmap -sV [target ip]

Stealth Scan: nmap -sS [target ip]

Identify The Remote Operating System: nmap -O [target ip]

Of course all of those different flags can be combined or mixed and matched, for example:

nmap -sS -sV -p21,23 192.168.0.10

If Ping is not allowed but host is up then use the belwo mention command

nmap -sS -sV -p 80 -Pn 1.1.1.1


How Network Traffic Flows

To troubleshoot an issue, you need to know how network traffic flows under normal circumstances. This article details what happens when a Web browser is used to access a Web site.

Once the Web site name is entered into a Web browser, a series of communications occurs over various protocols. The table below represents how the network traffic flows:

Line:	Protocol:	Source:	Destination:	Data:
1	ARP	10.0.1.13	Broadcast	Who has 10.0.1.1? Tell 10.0.1.13
2	ARP	10.0.1.1	10.0.1.13	10.0.1.1 is at 00:80:c8:57:d3:aa
3	DNS	10.0.1.13	10.0.1.1	Standard query A http://www.cyberguard.com
4	DNS	10.0.1.1	10.0.1.13	Standard query response CNAME cyberguard.com A 64.94.50.88
5	TCP	10.0.1.13	64.94.50.88	1939 > http [SYN]
6	TCP	64.94.50.88	10.0.1.13	http > 1939 [SYN, ACK]
7	TCP	10.0.1.13	64.94.50.88	1939 > http [ACK]
8	HTTP	10.0.1.13	64.94.50.88	GET / HTTP/1.1
9	HTTP	64.94.50.88	10.0.1.13	HTTP/1.1 200 OK
10	HTTP	64.94.50.88	10.0.1.13	HTTP Continuation
11	TCP	10.0.1.13	64.94.50.88	2577 > http [ACK] Seq=388864 Ack=37076821 Win=8241 Len=0
12	TCP	10.0.1.13	64.94.50.88	2577 > http [RST] Seq=388864 Ack=37077089 Win=0 Len=0

The ARP Protocol
Before systems can communicate, they need to know each other's hardware addresses. The Address Resolution Protocol (ARP) is used for this purpose. From its configuration, the workstation knows the IP address of the DNS server.
Line # 1

Protocol:	Source:	Destination:	Data:
ARP	10.0.1.13	Broadcast	Who has 10.0.1.1? Tell 10.0.1.13

The workstation broadcasts a request to the devices on its network asking "who has" the IP address it needs to communicate with.
Line # 2

Protocol:	Source:	Destination:	Data:
ARP	10.0.1.1	10.0.1.13	10.0.1.1 is at 00:80:c8:57:d3:aa

The remote system responds providing its hardware address. Now that the workstation knows the hardware address of the remote system, it can communicate with it.

The DNS Protocol

The Domain Name System (DNS) protocol is used to resolve system names to IP addresses. When a Web site name is entered into a browser, the workstation needs to know the corresponding IP address to reach the Web server hosting the site.
Line # 3

Protocol:	Source:	Destination:	Data:
DNS	10.0.1.13	10.0.1.1	Standard query A http://www.cyberguard.com

The workstation asks the DNS server to provide the IP address of the Web server hosting www.cyberguard.com.
Line # 4

Protocol:	Source:	Destination:	Data:
DNS	10.0.1.1	10.0.1.13	Standard query response CNAME cyberguard.com A 64.94.50.88

The DNS server responds with the IP address corresponding to www.cyberguard.com.

The TCP Protocol
The Transmission Control Protocol (TCP) protocol is used to transfer data. These next three lines comprise the TCP three-way handshake:
Line # 5

Protocol:	Source:	Destination:	Data:
TCP	10.0.1.13	64.94.50.88	1939 > http [SYN]

The workstation initiates the connection to the Web server (SYN). SYN is an abbreviation for "synchronize."
Line # 6

Protocol:	Source:	Destination:	Data:
TCP	64.94.50.88	10.0.1.13	http > 1939 [SYN, ACK]

The Web server responds back indicating that it is ready for transmission (SYN ACK). SYN ACK is an abbreviation for "synchronize acknowledgement."
Line # 7

Protocol:	Source:	Destination:	Data:
TCP	10.0.1.13	64.94.50.88	1939 > http [ACK]

The workstation sends to the Web server indicating that it is starting to send traffic (ACK). This acknowledgement indicates that the TCP connection is established and traffic can begin to flow.

The HTTP Protocol
The Hyper Text Transfer Protocol (HTTP) is used to serve up Web pages. You can see evidence of this from the Web site address in your browser (e.g. http://www.cyberguard.com).
Line # 8

Protocol:	Source:	Destination:	Data:
HTTP	10.0.1.13	64.94.50.88	GET / HTTP/1.1

The browser opens a connection to the Web server.
Line # 9

Protocol:	Source:	Destination:	Data:
HTTP	64.94.50.88	10.0.1.13	HTTP/1.1 200 OK

The Web server accepts the connection.
Line # 10

Protocol:	Source:	Destination:	Data:
HTTP	64.94.50.88	10.0.1.13	HTTP Continuation

The HTTP Continuation lines represent where the contents of the html page are sent over. It includes text, links, etc.

Back to the TCP Protocol
Line # 11

Protocol:	Source:	Destination:	Data:
TCP	10.0.1.13	64.94.50.88	2577 > http [ACK] Seq=388864 Ack=37076821 Win=8241 Len=0

This line is actually repeated four times. The workstation is acknowledging the last packet.
Line # 12 (RST)

Protocol:	Source:	Destination:	Data:
TCP	10.0.1.13	64.94.50.88	2577 > http [RST] Seq=388864 Ack=37077089 Win=0 Len=0

The workstation sends a reset, effectively tearing down the TCP connection.

(Note: Reference of the post "How Network Traffic Flows" is http://www.gideonrasmussen.com/article-03.html)