How to i calculate ip address range from subnet mask

ipnetworkingsubnet

When I use this command which IP addresed are scanned

# nmap -sP 192.168.0.120/25

How can I get the IP range when I have the addres and subnet. Because I am trying to understand this, but no result till now..Please help me..Thank a lot

Best Answer

You can use ipcalc, a nice *nix tool to guide you:

    ~ $  ipcalc 192.168.0.120/25
    Address:   192.168.0.120        11000000.10101000.00000000.0 1111000
    Netmask:   255.255.255.128 = 25 11111111.11111111.11111111.1 0000000
    Wildcard:  0.0.0.127            00000000.00000000.00000000.0 1111111
    =>
    Network:   192.168.0.0/25       11000000.10101000.00000000.0 0000000
    HostMin:   192.168.0.1          11000000.10101000.00000000.0 0000001
    HostMax:   192.168.0.126        11000000.10101000.00000000.0 1111110
    Broadcast: 192.168.0.127        11000000.10101000.00000000.0 1111111
    Hosts/Net: 126                   Class C, Private Internet

New answer, powershell

TCP

Get-Process -Id (Get-NetTCPConnection -LocalPort YourPortNumberHere).OwningProcess

UDP

Get-Process -Id (Get-NetUDPEndpoint -LocalPort YourPortNumberHere).OwningProcess

Old answer, cmd

 C:\> netstat -a -b

(Add -n to stop it trying to resolve hostnames, which will make it a lot faster.)

Note Dane's recommendation for TCPView. It looks very useful!

-a Displays all connections and listening ports.

-b Displays the executable involved in creating each connection or listening port. In some cases well-known executables host multiple independent components, and in these cases the sequence of components involved in creating the connection or listening port is displayed. In this case the executable name is in [] at the bottom, on top is the component it called, and so forth until TCP/IP was reached. Note that this option can be time-consuming and will fail unless you have sufficient permissions.

-n Displays addresses and port numbers in numerical form.

-o Displays the owning process ID associated with each connection.

Calculating range of IPs from subnet mask

A netmask is a series of 1 bits. The bits must be sequential with no 0 gaps. Anything using a 1 bit is part of the network, anything remaining is valid for host assignment within that network. A 255.255.255.224 has 27 "1" bits, which means it's a /27 network.

To calculate this right, you need to convert IPs to a numeric representation. For example, 255.255.255.224 is 11111111 11111111 11111111 11100000 which is 4294967264. 192.168.1.101 is 3232235877 (11000000 10101000 00000001 01100101).

If you take the IP and bitwise AND it with the netmask, that gives you the network address. This is the bottom end of the range:

11111111 11111111 11111111 11100000  (mask)
11000000 10101000 00000001 01100101  (ip)
-----------------------------------
11000000 10101000 00000001 01100000  = 192.168.1.96  (network address)

The complement (bitwise NOT) of the mask gives you the size of the range:

00000000 00000000 00000000 00011111  = 31

Thus, the range for that IP is between 192.168.1.96 - 192.168.1.127. (127 = 96 + 31)

Best Answer

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