Objective: you want to convert between different types of netmasks and network addresses, or generate optimized netmasks for firewall rules. netmask can take care of your netmasks!
This program accepts and produces a variety of common network address
and netmask formats. Not only can it convert address and netmask notations, but it will optimize the masks to
generate the smallest list of rules. This is very handy if you’ve ever configured a firewall or
router and some nasty network administrator before you decided that
base 10 numbers were good places to start and end groups of machines.
This is netmask, an address netmask generation utility
Usage: netmask spec [spec ...]
-h, --help Print a summary of the options
-v, --version Print the version number
-d, --debug Print status/progress information
-s, --standard Output address/netmask pairs
-c, --cidr Output CIDR format address lists
-i, --cisco Output Cisco style address lists
-r, --range Output ip address ranges
-x, --hex Output address/netmask pairs in hex
-o, --octal Output address/netmask pairs in octal
-b, --binary Output address/netmask pairs in binary
-n, --nodns Disable DNS lookups for addresses
-f, --files Treat arguments as input files
Definitions:
a spec can be any of:
address
address:address
address:+address
address/mask
an address can be any of:
N decimal number
0N octal number
0xN hex number
N.N.N.N dotted quad
hostname dns domain name
a mask is the number of bits set to one from the left