+description:
+ Hath is a Haskell program for working with network blocks in CIDR
+ notation. When dealing with blocks of network addresses, there are a
+ few things that one usually wants to do with them:
+ .
+ * Create a regular expression matching the CIDR block(s). This is
+ because grep will throw up if you feed it CIDR.
+ .
+ * Combine small blocks into larger ones. For example, if you have two
+ consecutive \/24s, they might combine into a larger \/23.
+ .
+ * View the result of block combination in a useful way.
+ .
+ * List them.
+ .
+ * Find their associated PTR records.
+ .
+ Hath has several modes to perform these functions:
+ .
+ [@Regexed@]
+ This computes a (Perl-compatible) regular expression matching
+ the input CIDR blocks. It's the default mode of operation.
+ .
+ [@Reduced@]
+ This combines small blocks into larger ones where possible, and
+ eliminates redundant blocks. The output should be equivalent to
+ the input, though.
+ .
+ [@Duped@]
+ Shows only the blocks that would be removed by reduce; that is, it
+ shows the ones that would get combined into larger blocks or are
+ simply redundant.
+ .
+ [@Diffed@]
+ Shows what would change if you used reduce. Uses diff-like
+ notation.
+ .
+ [@Listed@]
+ List the IP addresses contained within the given CIDRs.
+ .
+ [@Reversed@]
+ Perform reverse DNS (PTR) lookups on the IP addresses contained
+ within the given CIDRs.
+ .
+ /Examples/:
+ .
+ Compute a (Perl-compatible) regular expression matching
+ the input CIDR blocks. It's the default mode of operation.
+ .
+ @
+ $ hath <<< \"10.0.0.0\/29 10.0.0.8\/29\"
+ ((10)\.(0)\.(0)\.(15|14|13|12|11|10|9|8|7|6|5|4|3|2|1|0))
+ @
+ .
+ Combine two \/24s into a \/23:
+ .
+ @
+ $ hath reduced <<< \"10.0.0.0\/24 10.0.1.0\/24\"
+ 10.0.0.0/23
+ @
+ .
+ List the addresses in 192.168.0.240\/29:
+ .
+ @
+ $ hath listed <<< 192.168.0.240\/29
+ 192.168.0.240
+ 192.168.0.241
+ 192.168.0.242
+ 192.168.0.243
+ 192.168.0.244
+ 192.168.0.245
+ 192.168.0.246
+ 192.168.0.247
+ @
+ .
+ Perform PTR lookups on all of 198.41.0.4\/30:
+ .
+ @
+ $ hath reversed <<< 198.41.0.4\/30
+ 198.41.0.4: a.root-servers.net.
+ 198.41.0.5:
+ 198.41.0.6: rs.internic.net.
+ 198.41.0.7:
+ @
+ .
+ The DNS lookups are usually the bottleneck for this mode, but we can
+ perform them in parallel. Simply pass the number of threads to the
+ GHC runtime on the command line; for example, the following will
+ perform 25 lookups in parallel:
+ .
+ @
+ $ hath reversed +RTS -N25 <<< 198.41.0.4\/24
+ 198.41.0.4: a.root-servers.net.
+ 198.41.0.5:
+ 198.41.0.6: rs.internic.net.
+ ...
+ @
+ .
+ The command-line syntax and complete set of options are documented in
+ the man page.