Packages and Binaries:

whatmask

This package contains a small C program that will help you with network settings. Whatmask can work in two modes. The first mode is to invoke Whatmask with only a subnet mask as the argument. In this mode Whatmask will echo back the subnet mask in four formats, plus the number of useable addresses in the range. The second mode is to invoke Whatmask with any ip address within the subnet, followed by a slash (’/’), followed by the subnet mask in any format. Whatmask will echo back the following:

  • The netmask in the following formats: CIDR, Netmask, Netmask (Hex) Wildcard Bits
  • The Network Address
  • The Broadcast Address
  • The number of Usable IP Addresses
  • The First Usable IP Address
  • The Last Usable IP Address

Installed size: 40 KB
How to install: sudo apt install whatmask

  • libc6
whatmask

Subnet mask notation conversion tool.

[email protected]:~# man whatmask
Whatmask(1)                         Network                        Whatmask(1)

NAME
       whatmask - Subnet mask notation conversion tool.

SYNTAX
       whatmask <netmask or ip/netmask>
       see the Examples section below

DESCRIPTION
       Whatmask is a small C program that will help you with network settings.

       Whatmask  can  work in two modes.  The first mode is to invoke Whatmask
       with only a subnet mask as the argument. In  this  mode  Whatmask  will
       echo  back  the subnet mask in four formats, plus the number of useable
       addresses in the range.

       Netmask Notations supported:
        Name                  Example

        CIDR                         /24
        Netmask            255.255.255.0
        Netmask (hex)         0xffffff00
        Wildcard Bits           0.0.0.255

       The above notations are all identical.  CIDR notation  commonly  has  a
       "/" in front of the number (representing the number of bits).  Whatmask
       can accept these notations with or without a slash.  This  notation  is
       used more and more recently. A lot of popular routers and software sup-
       port this notation.

       Netmask notation is pretty much the standard old-school  way  of  doing
       it. It is supported by most systems (Un*x, Win, Mac, etc.).

       Netmask  (Hex)  is  the hexadecimal representation of the netmask. Many
       implementations of ifconfig use this notation

       Wildcard Bits are similar to the netmask, but they are the logical  not
       of  the  netmask.  This notation is used by a number of popular routers
       (and nobody knows why...).

       To use Whatmask in the first mode simply type "whatmask <notation>" The
       notation  can be in any of the four formats and Whatmask will automagi-
       cally figure out what it is and display all four notations.

       To use Whatmask in its second mode execute Whatmask with any ip address
       within  the  subnet,  followed by a slash ('/'), followed by the subnet
       mask   in   any   format.   (e.g.   192.168.0.23/255.255.255.224,    or
       192.168.0.23/27) Put no spaces in the argument.

       Whatmask will echo back the following:

       -  The  netmask in the following formats: CIDR, Netmask, Netmask (Hex),
       Wildcard Bits

       - The Network Address

       - The Broadcast Address

       - The number of Usable IP Addresses

       - The First Usable IP Address

       - The Last Usable IP Address

              (Whatmask assumes that the Broadcast address is the highest  ad-
              dress in the subnet. This is the most common configuration.)

OPTIONS
       <no options> see above and below for usage.

EXAMPLES
       Examples of how Whatmask works:

            myhost> whatmask /26

            ---------------------------------------------
                    TCP/IP SUBNET MASK EQUIVALENTS
            ---------------------------------------------
            CIDR = .....................: /26
            Netmask = ..................: 255.255.255.192
            Netmask (hex) = ............: 0xffffffc0
            Wildcard Bits = ............: 0.0.0.63
            Usable IP Addresses = ......: 62

            myhost> whatmask 255.255.192.0

            ---------------------------------------------
                    TCP/IP SUBNET MASK EQUIVALENTS
            ---------------------------------------------
            CIDR = .....................: /18
            Netmask = ..................: 255.255.192.0
            Netmask (hex) = ............: 0xffffc000
            Wildcard Bits = ............: 0.0.63.255
            Usable IP Addresses = ......: 16,382

            myhost> whatmask 0xffffffe0

            ---------------------------------------------
                    TCP/IP SUBNET MASK EQUIVALENTS
            ---------------------------------------------
            CIDR = .....................: /27
            Netmask = ..................: 255.255.255.224
            Netmask (hex) = ............: 0xffffffe0
            Wildcard Bits = ............: 0.0.0.31
            Usable IP Addresses = ......: 30

            myhost> whatmask 0.0.0.31

            ---------------------------------------------
                    TCP/IP SUBNET MASK EQUIVALENTS
            ---------------------------------------------
            CIDR = .....................: /27
            Netmask = ..................: 255.255.255.224
            Netmask (hex) = ............: 0xffffffe0
            Wildcard Bits = ............: 0.0.0.31
            Usable IP Addresses = ......: 30

            myhost> whatmask 192.168.165.23/19

            ------------------------------------------------
                         TCP/IP NETWORK INFORMATION
            ------------------------------------------------
            IP Entered = ..................: 192.168.165.23
            CIDR = ........................: /19
            Netmask = .....................: 255.255.224.0
            Netmask (hex) = ...............: 0xffffe000
            Wildcard Bits = ...............: 0.0.31.255
            ------------------------------------------------
            Network Address = .............: 192.168.160.0
            Broadcast Address = ...........: 192.168.191.255
            Usable IP Addresses = .........: 8,190
            First Usable IP Address = .....: 192.168.160.1
            Last Usable IP Address = ......: 192.168.191.254

            myhost> whatmask 192.168.0.13/255.255.255.0

            ------------------------------------------------
                         TCP/IP NETWORK INFORMATION
            ------------------------------------------------
            IP Entered = ..................: 192.168.0.13
            CIDR = ........................: /24
            Netmask = .....................: 255.255.255.0
            Netmask (hex) = ...............: 0xffffff00
            Wildcard Bits = ...............: 0.0.0.255
            ------------------------------------------------
            Network Address = .............: 192.168.0.0
            Broadcast Address = ...........: 192.168.0.255
            Usable IP Addresses = .........: 254
            First Usable IP Address = .....: 192.168.0.1
            Last Usable IP Address = ......: 192.168.0.254

            myhost> whatmask 192.168.0.113/0xffffffe0

            ------------------------------------------------
                         TCP/IP NETWORK INFORMATION
            ------------------------------------------------
            IP Entered = ..................: 192.168.0.113
            CIDR = ........................: /27
            Netmask = .....................: 255.255.255.224
            Netmask (hex) = ...............: 0xffffffe0
            Wildcard Bits = ...............: 0.0.0.31
            ------------------------------------------------
            Network Address = .............: 192.168.0.96
            Broadcast Address = ...........: 192.168.0.127
            Usable IP Addresses = .........: 30
            First Usable IP Address = .....: 192.168.0.97
            Last Usable IP Address = ......: 192.168.0.126

            myhost> whatmask 192.168.0.169/0.0.0.127

            ------------------------------------------------
                         TCP/IP NETWORK INFORMATION
            ------------------------------------------------
            IP Entered = ..................: 192.168.0.169
            CIDR = ........................: /25
            Netmask = .....................: 255.255.255.128
            Netmask (hex) = ...............: 0xffffff80
            Wildcard Bits = ...............: 0.0.0.127
            ------------------------------------------------
            Network Address = .............: 192.168.0.128
            Broadcast Address = ...........: 192.168.0.255
            Usable IP Addresses = .........: 126
            First Usable IP Address = .....: 192.168.0.129
            Last Usable IP Address = ......: 192.168.0.254

BUGS
       Report bugs to <[email protected]>

CONTRIBUTORS
       Original code:
              Joe Laffey <[email protected]>

       Assistance with Manpage and Packaging:
              David Wirch <[email protected]>

       Many  thanks  to  the beta testers and users who sent in valuable feed-
       back!

UPDATES
       Official Whatmask website:
              http://www.laffeycomputer.com/whatmask.html

LAFFEY Computer Imaging          Nov 14, 2003                      Whatmask(1)

Updated on: 2022-May-06