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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

     subnetcalc ç´è±.w3.mag.keio.ac.jp 29

AUTHORS

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