NAME

     subnetcalc — IPv4/IPv6 Subnet Calculator

SYNOPSIS

     subnetcalc [Address] [Netmask/Prefix] [-n] [-uniquelocal] [-uniquelocalhq]

DESCRIPTION

     subnetcalc is an IPv4/IPv6 subnet address calculator. For given IPv4 or IPv6 address and
     netmask or prefix length, it calculates network address, broadcast address, maximum number
     of hosts and host address range. Also, it prints the addresses in binary format for better
     understandability. Furthermore, it prints useful information on specific address types (e.g.
     type, scope, interface ID, etc.).

ARGUMENTS

     The following arguments have to be provided:

     Address
             The IP address. If a hostname is provided here, it is tried to resolve the address
             by a DNS server and the first returned address is used. Internationalized Domain
             Names (IDN) are supported.

     Netmask/Prefix
             The netmask or prefix length (0-32 for IPv4; 0-128 for IPv6).

     -n      Skip trying a reverse DNS lookup.

     -uniquelocal
             Given an IPv6 address, the first 48 bits of the address are replaced by a randomly
             chosen IPv6 Unique Local prefix in fc00::/7 (see also RFC 4193). Under Linux,
             /dev/urandom is used for random number generation.

     -uniquelocalhq
             Like -uniquelocal, but using /dev/random instead on Linux systems for highest-
             quality random number generation. On other systems, this option is equal to
             -uniquelocal. Note, that reading from /dev/random may take some time. You can speed
             up this process by delivering random input e.g. by pressing keys or moving the
             mouse.

EXAMPLES

     subnetcalc 132.252.250.0 255.255.255.0

     subnetcalc 132.252.250.0/255.255.255.0

     subnetcalc 132.252.250.0 24

     subnetcalc 132.252.250.0/24

     subnetcalc fec0:2345:6789:1111:221:6aff:fe0b:2674 56

     subnetcalc 2a00:1450:8007::69 64

     subnetcalc ff08::1:2:3

     subnetcalc 131.220.6.5/24

     subnetcalc 132.252.181.87 -n

     subnetcalc www.iem.uni-due.de 24

     subnetcalc www.six.heise.de

     subnetcalc fd00:: 64 -uniquelocal

     subnetcalc fd00::9876:256:7bff:fe1b:3255 56 -uniquelocalhq

     subnetcalc düsseldorf.de 28

     subnetcalc www.köln.de

     subnetcalc räksmörgås.josefsson.org 24

AUTHORS

     Thomas Dreibholz
     http://www.iem.uni-due.de/~dreibh/subnetcalc
     mailto://dreibh@iem.uni-due.de